EHRM, 26-09-2023, nr. 15669/20

According to the information provided in the first part of the bill of indictment, the foundations of the organisation had been laid in 1966 by F. Gülen, who was serving as an imam and preacher (vaiz) at the time. At its inception, the organisation concentrated its activities on young students, whom it reached via F. Gülen's talks recorded on cassettes or through ‘conversation meetings’ (sohbet). By adapting himself to the socio-political conditions of the day, exploiting religious sentiments and maintaining his autonomy from political parties, F. Gülen was able to increase his effect in the ‘triangle of religion, politics and money’, and to thus expand his organisation and his influence in religious circles. During this first phase of its existence preceding the coup d'état of 12 September 1980, the organisation focused on increasing its support base — particularly through the ‘houses of light’ (ışık evleri) allocated to students, which were referred to in the bill of indictment as the ‘cell houses’ of the organisation, and private tutoring centres (dershane) that targeted students — and infiltrating public institutions.

In the next phase, which followed the coup d'état of 1980, the organisation completed its mission of ‘staffing’ public institutions, and prioritised its educational goals, while carrying on with other activities in secret. Targeting bright students and educating them formed a fundamental part of the organisation's long-term project, as it was these students who were subsequently placed in important public institutions by the organisation.

In this second phase, the organisation replaced its ideology of ‘national, local Islam’ with what the bill of indictment termed an ‘étatist discourse’. From an economic perspective, the organisation also started operating in this phase like a holding company that connected companies; accordingly, it founded a bank and commenced activities in the health, finance, transport and media sectors, in addition to its presence in the area of education. This second phase also marked the period when the FETÖ/PDY expanded abroad.

According to the bill of indictment, the third phase of FETÖ/PDY leading to terrorism started after the incident of the so called ‘post-modern coup d’état' of 28 February 1997 (for some further insight into this incident, see Dilipak and Karakaya v. Turkey, nos. 7942/05 and 24838/05, §§ 6 and 54, 4 March 2014). In this phase, F. Gülen fled from Türkiye, and the organisation changed its rhetoric and adopted more universal expressions, entailing references to concepts such as ‘dialogue between religions’ and ‘human rights’. It was noted that by this phase the organisation had become active in 160 countries and had also brought all public institutions in Türkiye under its influence. Particularly after the constitutional changes adopted on 12 September 2010, the organisation began to perceive itself as the only de facto ruler of the State, which perception continued until 17 December 2013 (see paragraph 19 above in relation to the so-called ‘17–25 December investigations’).

In this first part of the bill of indictment, the prosecutor's office also provided a description of the special terminology used by the organisation and its structure. It explained, in particular, the ‘cell-type organisation’ of the FETÖ/PDY within public institutions, which consisted of a maximum of five persons, subordinated to their hierarchical superior, named the ‘brother’ (örgüt abisi). This method of organisation was inspired by Hezbollah. The cells, which were the smallest organisational units within the FETÖ/PDY, were not aware of one another, so that if one cell was exposed, the others could continue their activities.

As for the organisation's objectives, the statements of persons who were formerly active in the FETÖ/PDY had revealed that the main goal was to take control of the constitutional bodies of the State through the use of its people and the financial power that it had accumulated by exploiting the religious feelings present in society. In order to infiltrate the public institutions and achieve this goal, the organisation had also resorted to clandestine acts, such as stealing university or civil-service entry exam questions, or arranging the dismissal of non-members from the civil service by fabricating evidence against them.

In arguing why the FETÖ/PDY should be classified as an ‘organisation’, the prosecutor's office noted factors such as its use of code names and private telecommunication channels instead of handling its affairs openly and transparently, its unaccounted finances and the management of its activities from abroad, its resort to duress, blackmail and illegal methods to eliminate its opponents, its covert dealings with foreign diplomatic missions, its perception of the State as an adversary, and its interpretation of religious values in pursuance of its objectives, adapting this interpretation to the prevailing circumstances of the day.

The prosecutor's office noted that the hierarchical structure of the FETÖ/PDY was based on the system of imams, each of whom was responsible for their assigned ‘units’ in their respective geographical, sectoral and institutional fields. Led by F. Gülen as ‘the universal imam’, the FETÖ/PDY had organised and spread at the grassroots level through continental, country, regional, provincial, district, trades, neighbourhood, and house imams. The organisation also designated imams in the public sector, such as ministries, local authorities and universities, and the private sector. Due to the sensitive nature of their assignments, the imams operating in the civil service, law enforcement, army, judiciary and the MİT took more precautions to preserve their secrecy compared to other members of the organisation, including as regards their means of communication.

At the outermost layer of the organisation were its ‘sympathisers’ who, while not properly part of the organisation, were essential to its function as its legitimacy depended on a large number of sympathisers.

The prosecutor's office further observed that having recognised early on the difficulties that waging an open fight against the State would involve, F. Gülen's aim was to reach his goals not by destroying the system, but by conquering all governmental structures from within. It had long been known to the public that the FETÖ/PDY was active in the police force, as well as in other public bodies, which had been instrumental in conducting its operations and furthering its goals.

The prosecutor's office indicated that the most important means of communication for the organisation was via ‘GSM lines’. As a rule, these lines would be registered under the name of a third person or a FETÖ/PDY-controlled entity, which meant that the subscription information would not disclose the real user. A new GSM line would be obtained approximately every three months, and the mobile device would be replaced along with the GSM line. According to the public prosecutor's office, this arrangement alone was an important indication of the FETÖ/PDY's engagement in illegal activities that they wished to keep hidden.

The members of the organisation avoided using each other's names in their communications, and the provincial and district imams generally used code names.

Applications such as Skype, Tango, WhatsApp, Viber, Line and Kakao Talk were also favoured on account of the possibility of encrypted communication that they provided at low cost. However, members in critical positions eventually abandoned those applications in favour of ByLock, which had allegedly been developed upon the instruction of F. Gülen for the exclusive use of the members of the FETÖ/PDY. The bill of indictment did not provide much further information on the characteristics of ByLock, except for explaining that it was an encrypted messaging application with an automatic message deletion feature. It also stated that the ByLock application could not be downloaded from the Internet, as it required a special installation file which could only be obtained from another member, which also showed that the application could only be accessed by the members of the organisation.

On 21 March 2017 the first hearing was held before the Kayseri Assize Court.

At the start of the hearing, the assize court admitted in evidence the ByLock report submitted by the KOM and noted that the report on the digital materials seized at the time of the search conducted on 6 September 2016 had not yet been submitted. After reading out the bill of indictment, the assize court invited the applicant to make his defence statements. The applicant stated, inter alia, that while he was the user of the GSM line indicated, he had never used ByLock, and pointed out that there was no information in the bill of indictment as to his alleged communication ‘content and [other] issues’. As regards his bank account at Bank Asya, the applicant reiterated that he had opened that account in relation to his assignment to a project conducted by his school, and that he had no other connection to that bank. As for his membership of the Aktif Eğitim-Sen trade union, the applicant claimed that he had joined it in 2014, following the announcement of certain incentives by the Government for trade union membership, but then had quit on 17 June 2016 and had not engaged in any illegal activities during his membership. He had also joined the Kayseri Voluntary Educators Association out of his interest in their activities, which offered various educational and cultural courses, and for the purpose of socialising. He had sought to leave that association in June 2016 as well, but was informed that it was in the process of liquidation, and it was subsequently closed down. The applicant lastly stated that he did not know about or understand the anonymous tip-off received regarding him, and that he did not accept it.

The applicant's lawyer added that there were no concrete data in the case file to establish that the structure in question was a terrorist organisation. According to the lawyer, it transpired from the statements of the President and the Prime Minister regarding this ‘structure’ that its terrorist aims, as well as its aspirations to take over the State and any other illegal aims that it harboured, had been unknown to the State authorities; the applicant could not therefore have been expected to have knowledge of those matters. Accordingly, the material and mental elements of the crime had not materialised. He further claimed that the data regarding ByLock could not constitute ‘evidence’ under the CCP, because (i) they were unlawful, in view of the method of their seizure, (ii) it was unclear how the raw data had been incorporated into the case file from a technical point of view, (iii) they were technically inadequate, and (iv) they could not be inspected. To the extent that the accusations brought against the applicant concerned his membership of a trade union and an association, the applicant's lawyer indicated that both had been established in accordance with the law and no illegal activities had been attributed to them.

The applicant's lawyer further requested the extension of the investigation so as to inquire about, inter alia, whether the said terrorist organisation had committed any crimes against the Turkish State, its institutions and its citizens, and how the ByLock data had been obtained and deciphered technically. The lawyer also requested that any specific ByLock data belonging to the applicant be included in the case file.

The Kayseri Assize Court dismissed the lawyer's request for the extension of the investigation, having regard to the evidence already available in the case file, including the various reports confirming the applicant's use of ByLock, and to the designation of the FETÖ/PDY as a terrorist organisation in a final judgment delivered by the Samsun Regional Court of Appeal on 7 March 2017.

Subsequently, the public prosecutor presented his submissions on the merits (esas hakkında mütalaa) and sought the applicant's conviction of the offence with which he was charged. Reiterating the arguments made in the bill of indictment, the public prosecutor claimed that in a bid to conceal its true aims, the FETÖ/PDY had made an effort to portray itself as a religious community (dini cemaat) or civil society movement, and had used code-names and private communication methods in order to ensure secrecy. Against this background, and bearing in mind that people from all parts of society had sympathised with this organisation without being aware of its real motives and aims, had offered it financial support and had taken part in its activities, the public prosecutor found it imperative to establish who had truly been a part of the organisation's hierarchy and had acted in accordance with its common purpose. In this connection, having regard to the applicant's membership of a trade union and an association that was affiliated with the FETÖ/PDY, and noting his intensive use of an encrypted application employed for organisational communication amongst the FETÖ/PDY members, there was no doubt that the applicant had been a part of the organisation's hierarchical structure and a member of that organisation.

The applicant and his lawyer repeated their defence submissions in response to the public prosecutor's opinion.

At the end of the hearing held on 21 March 2017, the Kayseri Assize Court convicted the applicant as charged on the basis of the evidence indicated in the bill of indictment and sentenced him to six years and three months' imprisonment. It also decided to order his release having regard, inter alia, to the time that he already spent in detention.

The judgment was divided into five parts. In the first part titled ‘the FETÖ/PDY Armed Terrorist Organisation’, the court made general remarks regarding the definition, types and components of a terrorist organisation, and then proceeded to examine, inter alia, the establishment, objectives, management and hierarchical structure of the FETÖ/PDY, as well as its financial structure and communication methods, largely along the same lines as the bill of indictment. The assize court stressed that the fact that the State security institutions infiltrated by the FETÖ/PDY were armed and were authorised to use those arms was a very important factor to demonstrate that the organisation was in fact armed and had a military tendency.

The second part of the judgment on the ‘Structure and Functioning of the Organisation’ provided an overview of the unlawful methods commonly employed by the organisation in order to achieve its ulterior motives, such as stealing exam questions for their supporters, fabricating evidence and depriving people of their liberty based on trumped up charges. Stressing that maintaining secrecy was the key to the organisation's functioning, the assize court quoted some statements by F. Gülen allegedly instructing his followers to act discreetly and keep a low profile until they reached ‘all power centres’, which showed that the organisation had infiltrated all public institutions as a strategic means of seizing control over the constitutional order (see paragraph 162 below for some of these instructions, as noted in the judgment of the Court of Cassation dated 26 September 2017). The assize court further noted that the veil of secrecy had been lifted with the ‘bureaucratic coup attempt’ of 17–25 December 2013 (see paragraph 19 above and the references therein), which had been performed to ‘redesign the government and politics’. The assize court held that in view of its consequences, the 17–25 December events should be considered as a milestone for the recognition, at both the State and the public level, that the FETÖ/PDY was not an aid organisation or a ‘service’ movement but a terrorist organisation.

The third part of the judgment was devoted to an examination of the ByLock application. The court indicated that the application had been subjected to technical studies, including ‘reverse engineering, crypto analysis, web behaviour analysis and server response codes’, without providing further information as to who had carried out those analyses. It then provided a summary of the assessments made in the MİT technical analysis report (see paragraphs 114–116 below), without, however, referring expressly to that report, and concluded that under the guise of a global application, ByLock had been offered for the exclusive use of the members of the FETÖ/PDY.

In the fourth part of the judgment, the assize court examined the legal framework governing armed terrorist organisations in Türkiye and laid out the main elements of the offence of membership of an armed terrorist organisation, referring to the relevant provisions of the Criminal Code and the Prevention of Terrorism Act (see paragraphs 146–149 below). It noted, in particular, that membership of an organisation required voluntary submission and subordination to the organisation's hierarchical structure, as well as an ‘organic link’ to the organisation and participation in its activities. The organic link rendered the person available for commands and determined his or her hierarchical position and hence was the most important element of membership. Mere sympathy for the organisation would not constitute an offence.

In the fifth and the final part of the judgment, the assize court assessed the evidence on which it relied in convicting the applicant. In this connection, it noted that despite the applicant's denial, the ByLock report prepared by the Kayseri Security Directorate during the investigation stage and the report drawn up subsequently by the KOM at the trial stage had established that the applicant had used the ByLock application on his GSM line from 3 October 2015 onwards, with a telephone bearing the IMEI number 35368406164487. It had also been established that the applicant had been a member of a trade union and an association, both of which had been shut down on account of their affiliation with the FETÖ/PDY, and that he had deposited money with Bank Asya, similarly affiliated with that organisation. Elaborating on the latter point, the assize court stated that in contrast to the minimal activity in his Bank Asya account in the previous periods, in February 2014, upon the organisation's instructions, the applicant had made a deposit with the bank of an amount proportionate to his income — that is, TRY 3,110 — for the purpose of saving it from the economic hardships it encountered in the aftermath of the 17–25 December 2013 process.

Turning next to the applicant's allegations regarding the unlawfulness of the ByLock data on account of the failure to comply with the relevant provisions of the CCP in their collection, the assize court found that the data in question had been obtained by the MİT — within the framework of its powers under Law no. 2937 on Intelligence Services of the State and the National Intelligence Agency (‘the Law on Intelligence Services’) — from Lithuania, where the ByLock application's main server was located. Since the provisions of the CCP were not enforceable in Lithuania, it was not possible to argue that the data had been collected in an unlawful manner on account of non-compliance with the CCP in that respect. The court moreover explained that on 9 December 2016, the Ankara Fourth Magistrate's Court had ordered the analysis of the data handed over by the MİT in accordance with Article 134 of the CCP.

The assize court further stated that while membership of an association or trade union could not in itself constitute evidence of membership of an armed terrorist organisation, in the applicant's case membership of more than one entity affiliated with the FETÖ/PDY had been established, in addition to his use of the organisation's communication tool, ByLock. Having regard to the aims and the functioning of terrorist organisations, any facilities ensuring intra-organisational communication and allowing the flow of information regarding organisational activities ‘could not be assessed outside the organisational structure’, for only people who were part of the organisational hierarchy would be admitted to the communication network. It therefore found it established that the applicant, by virtue of his use of the ByLock application and the other evidence in the case file, had been a part of the hierarchical structure of FETÖ/PDY.

On 3 April 2017 the applicant appealed against the judgment of the Kayseri Assize Court. In his appeal, the applicant challenged, inter alia, what he deemed to be the retrospective classification of FETÖ/PDY as an armed terrorist organisation. According to the intelligence reports issued by the MİT, the aim of the FETÖ/PDY was to seize the State institutions and to replace the constitutional order. However, in its 50-year history, that organisation, which the applicant referred to as a ‘structure’, had not been associated with any such acts. Referring to the judgment delivered by the plenary criminal divisions of the Court of Cassation on 24 June 2008 as regards F. Gülen's acquittal of terrorism charges (see paragraphs 189–193 below), the applicant argued that the activities carried out by the structure had been found to be in compliance with the law. It was unclear to him which concrete acts undertaken after the Court of Cassation's ruling had given rise to a contrary finding as regards the organisation's objectives. While the bill of indictment referred to the ‘17–25 December operation’ as an act of terror, opposition political parties considered the acts carried out on 17–25 December 2013 to be an anti-corruption operation; therefore, its classification as a terrorist act was a political decision, not a legal one.

The applicant further asserted that bearing in mind that membership of an armed terrorist organisation was a crime of specific intent (özel kast), it was primordial to establish when that organisation had come into existence, when individuals who were affiliated with the relevant structure — which used to be highly regarded by the State authorities — solely for religious reasons had become aware of the terrorist intent and goals harboured by certain members, and when, and by which means, he had knowingly and willingly become part of that organisation. Stressing in particular the lawful nature of the acts attributed to him, the applicant criticised the trial court's silence on these matters. In the applicant's view, the accusation of membership of an armed terrorist organisation made against him had to be supported by an investigation by the prosecutor's office into the organisation's hierarchical structure in the province of Kayseri, and his place in that hierarchy.

As regards the evidence concerning his use of the ByLock application, the applicant claimed that the ByLock data had not been obtained in accordance with the relevant procedures set out in Articles 134 and 135 of the CCP; in fact, the circumstances in which the data had been obtained were unclear. According to the information provided by the MİT, it had conducted an intelligence operation to obtain the data from the application's main server located in Lithuania; however, the technical details as to how exactly it had accessed and analysed the data remained unknown. In such circumstances, there was no possibility to inspect the data and to verify whether they had been modified; a person who had been added to the ByLock user list had no way to challenge that. The applicant highlighted here that the three user lists shared by the MİT with the judicial authorities did not match. In the applicant's opinion, the evidence regarding the use of ByLock was unreliable also from a purely technical point of view, given that it was possible for one IP address to be allocated to more than one person.

The applicant added that according to the MİT technical analysis report, the ByLock application had been downloaded some 500,000 to 1 million times from open sources, yet there had been no judicial examination to determine who had downloaded it for organisational purposes and who for other reasons.

To conclude, the applicant argued that the trial court's judgment had failed to comply with the rules of procedure and the rule of law, since it had been given on the basis of an insufficient investigation and without resorting to the opinions of competent and independent experts, particularly in respect of the ByLock data, and it had not established the material and mental elements of the crime at issue.

In its preliminary report dated 10 May 2017, the Ankara Regional Court of Appeal requested the KOM to provide information as to (i) the characteristics of the ByLock application, its downloading to communication devices and the means and conditions of its use; (ii) whether it could be downloaded and used by anyone; (iii) whether the application was specifically used by members of an organisation for their communications within the framework of the organisation's activities and how this had been established; (iv) the characteristics of the application that distinguished it from other means of communication; (v) the time period that and the frequency with which the applicant had used the application; (vi) on which GSM lines and from which devices (with IMEI numbers) the applicant had used the application; and (vii) if identified, the content of exchanges over the application and the identity and telephone contact details of the persons with whom the exchanges had been made.

In the same report, the court of appeal also requested the Information and Communications Technologies Authority (‘the BTK’) to provide information regarding (i) the base station data, pertaining to both the GSM line reported to be used by the applicant and the device(s) used with that line, indicating the dates on which ByLock IP addresses had been accessed in the period between 3 September 2015 and 15 July 2016; and (ii) the communication records indicating the incoming and outgoing calls, the messages sent and received, and the base stations used between 1 January 2015 and 15 July 2016, as well as the IMEI numbers of the device(s) used.

On 3 June 2017 a document issued by the KOM entitled ‘ByLock Identification Report’ was included in the case file. The document bore the signature of two KOM officers, without further specifying their rank or functions. The report indicated that the ByLock database, which had been handed over by the MİT to the Ankara Chief Public Prosecutor's Office, had been transmitted to them by the latter on 16 December 2016 for examination. The analysis carried out on the ByLock subscriber lists had revealed that the applicant, who had been noted on the 114,060^th line of the 129,862-line subscriber list, had used the specified GSM number, that the IMEI number belonging to the device used for connection was 35368406164487, that the first date of connection that could be identified was 3 October 2015 and that the examinations conducted so far had not disclosed any content of communication through messages or emails.

On 12 June 2017 the BTK also submitted the communication records requested from it.

Upon the court of appeal's request, an expert report was subsequently drawn up by a digital forensics expert on the basis of all the information and records available in the case file and was submitted to the appeal court on 29 June 2017. According to this report, the applicant had accessed the ByLock application through his GSM line with the specified telephone number and that his ByLock user-ID number was 408783. The examination of the HTS (‘Historical Traffic Search’[2]) records pertaining to this GSM line in the period between 1 January 2015 and 16 July 2016, which had been procured by the BTK, revealed that the line had been used in phones with three different IMEI numbers, including the device with IMEI number 35368406164487, on which the ByLock application had been found to have been used, but which had not been found in the applicant's home or on his person at the time of his arrest. Over the relevant period, a total of 13,450 call, SMS and MMS records and 38,166 GPRS[3] records were detected on the relevant GSM line, most of which concerned communication with persons believed to be the applicant's kin bearing the same surname. The report further indicated that in the period between 11 August 2014 and 10 January 2015, when the said GSM line was used with the phone with IMEI number 35368406164487, communication had been established with the IP number 46.166.164.181 that belonged to ByLock servers on six different dates for a total of 380 times. This expert report was served on the applicant's lawyer on 21 September 2017.

At the hearing held on 9 October 2017, the applicant and his lawyer reiterated their previous defence statements. The lawyer further indicated that they did not accept the digital forensics expert's report described in paragraph 80 above, which was based on unlawfully obtained evidence, and requested the court to obtain a fresh report from a committee of three experts. He stressed that the material and mental elements of the crime of membership of an armed terrorist organisation had not materialised.

At the same hearing, the court dismissed the applicant's request for a new expert report. It also upheld the applicant's conviction based on the information and reports in the case file.

The court reviewed at the outset the different forms of organised crime under Turkish law and discussed the distinguishing factors of the offence of ‘membership of an armed organisation’ under Article 314 § 2 of the Criminal Code, as also addressed at first instance (see paragraph 67 above). The appeal court specified that although it was not necessary for a ‘member’ to have committed an actual crime in connection with the organisation's activities, the individual must nevertheless have made a specific material or moral contribution to the organisation's existence or reinforcement. The offences of aiding an organisation or committing a crime on behalf of the organisation also involved receiving orders from the organisation; however, the distinctive factor in the determination of membership of an organisation was the readiness of the suspected member to execute all instructions and orders given within the context of the organisational hierarchy, without questioning and with absolute submission. The member should have established an organic link with the organisation, which was the most important element of membership of an organisation, and taken part in its activities. In this connection, it was primordial to determine on the concrete facts of a case whether the individual's position within the armed organisation had reached a level warranting his consideration as a ‘member’ of that organisation. The appeal court also noted that the offence of membership of an armed organisation required a specific intent besides general intent. Since the terrorist organisation was founded for a specific purpose, the perpetrator had to know of that purpose and had to have a specific intent for its realisation.

Moving on to the specific considerations concerning the FETÖ/PDY, the appeal court reiterated the distinct attributes which rendered that organisation an ‘armed terrorist organisation’, following the same line of reasoning adopted by the first-instance court, and more recently by the Court of Cassation in its judgments of 24 April 2017 and 26 September 2017 (see paragraphs 162–163 below). It noted that the aim of this organisation was not to come to power through legitimate methods, but to dissolve the Parliament, the government and the other constitutional institutions by using force and violence, as demonstrated by the attacks carried out against several symbolic State buildings, including the Parliament building and the presidential compound, with heavy weaponry. It also stressed that the absence of a prior judicial ruling designating the FETÖ/PDY as a terrorist organisation did not preclude criminal liability for offences committed in connection with that organisation.

The appeal court next turned to the issue of the lawfulness of the ByLock evidence and held that, in accordance with the principle of free evaluation of evidence, all types of evidence, including electronic evidence, could be relied on in criminal proceedings, as long as it was obtained lawfully. It considered in this connection that the MİT had collected the relevant data in pursuance of its duties and powers under sections 4 (1) and 6 (1) of the Law on Intelligence Services (see paragraph 143–145 below), and that the judicial procedure had only started after the MİT's handover of the digital material to the judicial authorities, from which point onwards the investigation had to be carried out in accordance with the terms of the CCP. The Ankara Fourth Magistrates' Court had accordingly ordered the examination and processing of the data handed over by the MİT in accordance with Article 134 of the CCP. The acts undertaken to identify and assess the use of ByLock had therefore been lawful.

The appeal court then addressed the probative value of evidence demonstrating a person's use of ByLock and held as follows:

The appeal court noted that the ByLock application was developed as a ‘special software that could only be used by the members [of the FETÖ/PDY] over a special server and that enabled communication by the [members] amongst themselves using a special encryption method’. It observed that the application could be downloaded from the Internet, or obtained via memory cards or Bluetooth, and that while it was exceptionally available for download by all at the beginning of 2014, it was subsequently made available by members of the organisation by means of USB keys, memory cards or Bluetooth, as indicated in statements, messages and e-mails obtained. The downloading of the application was not sufficient to be able to use it for messaging; knowledge of the user-specific ID number assigned automatically by the system and the approval of the other party was required to engage in communication, which was in conformity with the cell-like structure of the organisation. Moreover, almost all of the transcribed content concerned organisational contact and activities of the FETÖ/PDY members and corresponded to the organisation's specific jargon. Based on the foregoing elements, and others noted at length previously by the MİT and the Court of Cassation (see paragraphs 115–116 and 158–160 below, respectively), the appeal court found that under the guise of a global application, ByLock was offered for the exclusive use of the members of the FETÖ/PDY armed terrorist organisation and had been used by its members since early 2014, as revealed by the members themselves. To that end, the appeal court held, echoing the Court of Cassation's landmark judgment of 26 September 2017 (see paragraph 160 below):

Turning to the specific facts of the applicant's case, the appeal court made the following findings:

Holding that the first-instance court had not erred in its assessment and findings, the Ankara Regional Court of Appeal Court dismissed the applicant's appeal.

As mentioned in paragraph 21 above, in early 2016 the MİT accessed the databases of the ByLock server. Following the analysis of the digital data obtained from the server, the MİT issued an 88-page technical analysis report, which it shared with the ‘relevant institutions’ on 24 October 2016.

According to the report, after getting hold of the relevant material, the MİT carried out elaborate technical analyses both on the mobile application itself and on the application servers, on matters such as the application's technical design, operation, its similarities and differences to applications that provided the same functions, and the decrypted user profiles. In summary, the MİT's main findings regarding the ByLock application were:

The report concluded that when taken as a whole, the above factors suggested that ByLock had served as a messaging system for the exclusive use of FETÖ/PDY members, under the guise of a global application, which was also corroborated by statements obtained from a number of suspected members of the organisation in investigations conducted after the coup attempt.

This report, dated 2 April 2020, was prepared by the KOM at the request of the Ankara Chief Public Prosecutor's Office. The report largely reiterated the findings in the MİT report, but also made the following observations:

Based on the foregoing, and all the other information available, the report concluded that ByLock was a communication tool designed for the sole use of members of the FETÖ/PDY, that measures had been put in place to prevent the identification of users, and that it was not accessible to anyone outside the organisation.

The report also provided further insight as to how the ByLock user lists had been drawn up by the authorities. In the first stage, the MİT had identified, on the basis of the raw log data that it had obtained, the nine different IP addresses used by the ByLock server, the accuracy of which had been verified by the Department of Cyber Crimes of the General Directorate of Security. The Internet traffic data, also referred to as the CGNAT data[6], stored by the service providers in accordance with the relevant legislative framework had then been examined for the purpose of identifying the IP addresses that had connected to the ByLock server's nine IP addresses from Türkiye, although the user information thus obtained was limited to the connections that were made prior to the obligation to connect via VPN, or to instances where the VPN connection was momentarily disabled. The IP addresses thus identified were then matched to the respective GSM and ADSL subscribers. The first version of the user list was transmitted by the MİT to the Ankara Chief Public Prosecutor's Office on 16 December 2016. Upon further analysis of the available data, an updated list was prepared by the MİT and shared with the authorities on 24 March 2017. That list, which included information pertaining to 129,862 users, was then verified using the CGNAT data procured by the BTK from the service providers as of 19 April 2017 and the ByLock user list was thus put together. Subsequently, on 28 December 2017, 11,480 people who were discovered to have been unwittingly directed to the ByLock server, via a trap application known as Mor Beyin (‘Purple Brain’), were removed from the ByLock user list (for further information on Mor Beyin, see Taner Kılıç v. Turkey (no. 2), no. 208/18, § 36, 31 May 2022).

In a supplementary report drawn up on 22 May 2020, officers from the KOM responded to some specific questions put by the Ankara Chief Public Prosecutor's Office. In response to a question on the measures taken to ensure the integrity of the ByLock data and to prevent their manipulation, it was reiterated that the ByLock data had been obtained from two different sources: (i) the raw log data obtained by the MİT from the ByLock server; and (ii) the CGNAT data (pertaining to the Internet traffic information) showing connections made to the ByLock IPs from Türkiye. The first set of data was subjected to a disk imaging process and accorded a hash value, and the data was kept in a safe by the judicial authorities and could not, therefore, be modified. As for the CGNAT data, they concerned internationally registered data which could not be altered or corrupted.

In response to another query as to whether an individual ByLock user could be given the digital (raw) ByLock data pertaining to him or her alone, the report explained that it was not possible to sort the raw data on a user ID basis without first processing them. The raw ByLock data were categorised under separate tables on a database, and the information belonging to a particular individual was obtained following the extraction of the relevant data from these tables, through the use of an interface. The information thus obtained was included in each individual's case file, in the form of a ‘ByLock Results and Evaluation Report’. It was otherwise not possible to share the raw data in their entirety with any particular suspect, as that data contained information concerning many other suspects as well.

It was also indicated in this supplementary report that there had been no prosecutions for the mere download of ByLock and that evidence of the actual use of ByLock was required in each case.

On 10 July 2020 a group of cyber security experts, who were commissioned by the authorities, prepared an expert report on the ByLock application, on the basis of information obtained from open sources as well as from the reports prepared by the MİT and the KOM referred to above. While the expert report mainly reiterated the findings in those earlier reports, it also included some further pertinent observations (for a more detailed account of this report, see Akgün, cited above, § 57).

In this connection, the report noted that the ByLock application used advanced encryption methods and that it was an anonymity-oriented messaging application, which enabled communication without leaving a digital fingerprint that could be detected by the law-enforcement authorities. Some of its features, such as the storage of all messages in the server in an encrypted manner and the special procedure for adding contacts, demonstrated that ByLock had been designed differently from other messaging applications and intended to serve not the general public but a specific purpose.

The report also noted that some ‘trap’ applications (as mentioned in paragraph 119 above) that were used to establish inadvertent connections to the ByLock server had been identified. The technical analysis had shown that the CGNAT data pertaining to such inadvertent connections could be distinguished from the data produced following an ordinary connection to the ByLock server.

The report further emphasised that according to the information obtained from Google Trends on the searches conducted regarding ByLock on the Google search engine, virtually no searches had been made from September 2014 to February 2016. Given that ByLock worked very differently from other messaging applications, the absence of online searches suggested that this application was used by a specific group of people and that those people possessed detailed information on how the application worked and shared it with prospective users.

Lastly, as regards the number of users of the ByLock application, the report clarified that the figure ‘215‘092’ found in the MİT report indicated not the actual number of users, but the number of registrations with the application.

IntaForensics, a digital forensics and cyber security consultancy service based in the United Kingdom, prepared a forensic investigation and technical report on the ByLock application, dated 21 August 2020, at the request of the Ministry of Justice of Türkiye (for further details on the report, see Akgün, cited above, § 58).

The report, which was very similar in content to the reports outlined above, noted that despite the fact that ByLock was published on global application stores, for all intents and purposes the interest in it was limited to Türkiye. Moreover, given its difference in features when compared with other messaging applications, it would appear that anonymity as much as security was a primary goal for ByLock.

It was also observed in the report that the application had been removed from the Google Play store on 3 April 2016, yet no prior announcements had been made to the users on this matter, nor were any complaints or comments from users identified on social media or elsewhere as to why the application had been unpublished without notice. According to the authors of the report, this suggested that the application was used by a specific group of people and that the developer had no commercial concerns.

On 5 September 2021 the applicant's lawyer commissioned a digital forensics expert based in Türkiye to examine the CGNAT data and HTS records included in the applicant's case file, as well as the ‘Findings and Evaluation Report’ issued by the KOM on 7 October 2020 (see paragraph 107 above). In a report dated 11 October 2021, the expert noted that the IP addresses indicated in the CGNAT data pertaining to the applicant were all within the IP ranges blocked by the system administrator. He further found, inter alia, that while the relevant data suggested that connection with the ByLock server may have been established from the applicant's device, the nature of the data available did not rule out the possibility that the connections had been made other than by use of the ByLock application, i.e., inadvertently.

The applicant also submitted a number of expert reports that had been prepared by independent experts in the context of other criminal proceedings concerning the use of ByLock.

One of those reports, which had been prepared by a Netherlands-based IT company on 13 September 2017 and which mainly involved an analysis of the MİT technical analysis report, found that the said report entailed no information that would enable the verification of the integrity of the data obtained, such as hash values or an audit trail, nor did it provide a description of the technical analysis undertaken. As such, it was difficult to scrutinise the analysis methods used.

Another report, issued on 1 September 2021 by two legal forensics experts from Türkiye, concerned specifically the question whether there was sufficient evidence to support the conclusion that the ByLock application had been used ‘exclusively’ by members of the FETÖ/PDY. The report included the following findings, as relevant:

Based on the foregoing, the report found that the ByLock features identified by the authorities as proof of its exclusive use did not prove beyond reasonable doubt, from a technical perspective, that the said application had been meant for ‘exclusive use’. It added that any communication content which was not related to the organisation in question, of which there was plenty according to the records included in the case files, would undermine the ‘exclusiveness’ argument.

The relevant provisions of the Code of Criminal Procedure read as follows at the material time:

Article 134

Search, copying and seizure of computers, computer programs and logs

Article 135

Interception, wiretapping and recording of communications

Article 206

Production and rejection of evidence

Article 217

Discretion to evaluate evidence

Section 4 (1) of the Law provides as follows, as relevant:

Sections 6 (1) and (2) of the same Law read as follows, insofar as relevant:

Additional section 1 of the same Law provides as follows, as relevant:

Article 220 of the Criminal Code, which concerns the offence of forming an organisation with the aim of committing a criminal offence, provides as follows, as relevant:

Article 314 §§ 1 and 2 of the Criminal Code provides for the offence of membership of an armed organisation:

Parts four and five of the chapter to which Article 314 § 1 refers list offences against State security and against the constitutional order and its functioning.

Article 30 of the Criminal Code reads as follows:

Mistake

Article 30

The relevant provisions of the Prevention of Terrorism Act provide as follows:

Definition of Terrorism

Section 1

(before amendment by Law no. 4928 of 15 July 2003)

Section 1

(as amended by Law no. 4928 of 15 July 2003)

Terrorist Offenders

Section 2

Terrorist Offences

Section 3

Terrorist Organisations

Section 7

On 1 July 2016 the Turkish Parliament enacted Law no. 6723, which amended certain laws, including the Court of Cassation Act (Law No. 2797). Section 22 of Law no. 6723, which entered into force on 23 July 2016, added a provisional article to Law no. 2797. This section mainly provided for the cessation, with certain exceptions, of the terms of office of the members of the Court of Cassation as of the date of its entry into force and reduced the total number of members to be re-elected. It further stipulated that those judges who were not re-elected as members of the Court of Cassation would be appointed by the High Council of Judges and Prosecutors to another position in accordance with their class and grade.

Article 3 § 1 of Legislative Decree no. 667, which came into force on 23 July 2016 as part of the state of emergency measures, provided, inter alia, that judges and prosecutors, including the members of the Constitutional Court and the higher courts, would be dismissed from office if they were considered to belong to, be affiliated with or linked to terrorist organisations or organisations, structures or groups which the National Security Council had established were engaged in activities prejudicial to national security. The dismissal decision was to be taken by the absolute majority of the Constitutional Court, sitting in plenary formation, in respect of the members of the Constitutional Court, by the First Presidency Board of the Court of Cassation in respect of the members of the Court of Cassation, and by the High Council of Judges and Prosecutors in respect of prosecutors and judges who were not members of the high courts.

On 18 October 2016, the Turkish Parliament adopted Law no. 6749 (published in the Official Gazette on 29 October 2016), approving Legislative Decree no. 667. Article 3 § 1 of Legislative Decree no. 667 was incorporated into Article 3 § 1 of Law no. 6749.

Legislative Decree no. 685 adopted on 2 January 2017 provided in its Article 11 that persons who had been dismissed from their duties under Article 3 § 1 of Legislative Decree no. 667 and Law no. 6749 could challenge the measure before the Supreme Administrative Court, acting as a court of first instance.

On 24 April 2017 the Sixteenth Criminal Division of the Court of Cassation (‘the Sixteenth Criminal Division’), sitting as a first-instance court, delivered a judgment (E.2015/3, K.2017/3), whereby it convicted two judges, namely M.Ö. and M.B., of membership of the FETÖ/PDY and abuse of office. This was the first judgment by the Court of Cassation holding the said organisation to be a ‘terrorist organisation’. In reaching this verdict, the high court relied on the use of the ByLock messaging system by the judges concerned, as well as on evidence demonstrating that they had adopted judicial decisions — which involved releasing sixty-three suspects detained in connection with FETÖ/PDY-related charges — on the basis of an encrypted instruction by F. Gülen published on a FETÖ/PDY-affiliated website (see Başer and Özçelik v. Türkiye, nos. 30694/15 and 30803/15, 13 September 2022 for further details relating to the charges brought against these two judges). On 26 September 2017 the plenary criminal divisions of the Court of Cassation upheld this judgment (no. E. 2017/16-956, K. 2017/370).

In these two judgments (hereinafter referred to as the ‘the landmark judgments’), which shaped the course of all ensuing criminal proceedings involving the use of ByLock, the Court of Cassation made important findings as regards the legal framework regulating the collection of the ByLock data, the nature and features of the ByLock application and its probative value, and the structure of the FETÖ/PDY.

The judgment delivered by the plenary criminal divisions of the Court of Cassation on 27 June 2019 (E.2018/16-418, K.2019/513) provided further information on how the raw data obtained from the ByLock server and the CGNAT data had been assessed in establishing whether a person had used the ByLock application. The relevant paragraph from this judgment provides as follows:

According to the Court of Cassation, the presence of CGNAT data showing a person's connection to the ByLock IP addresses, in circumstances where no ByLock user ID had been discovered, could mean one of these two things: either the KOM inquiry on the data obtained from the ByLock server had not yet been completed — or the relevant data could not be recovered or transcribed —, or the person in question had been unwittingly diverted to the ByLock server through traps such as via the application known as Mor Beyin (see paragraph 119 above), which was apparently developed and used to deliberately direct users of certain applications — mainly of an Islamic nature — to ByLock servers.

In the same vein, an earlier judgment delivered by the Sixteenth Criminal Division of the Court of Cassation on 29 April 2019 (E.2019/98, K.2019/3057) maintained that the presence of a user ID would demonstrate that a person had connected to the ByLock server directly, without any routing, and a detailed ByLock assessment and identification report would provide information on the identity of the real user, as well as his or her position within the organisation and activities. The Court of Cassation quashed the conviction in that case since, despite the presence of CGNAT data and a ByLock user report issued by the KOM, which constituted ‘significant indications’ as to the use of ByLock, the individual's user ID had not been identified and the possibility of inadvertent connections had therefore not been ruled out.

On 4 June 2020 the Plenary of the Constitutional Court delivered a judgment in the case of Ferhat Kara, which concerned the alleged violation of the right to a fair trial on the ground that the data regarding the use of ByLock had been obtained unlawfully and were relied on as sole or decisive evidence for conviction for membership of the FETÖ/PDY, and that the relevant digital data were not brought before the trial court.

The Constitutional Court commenced its examination by setting out the facts and the background to the case, providing an overview of the FETÖ/PDY and of the ByLock application, both in terms of its technical features and the manner in which the application data had been obtained and processed by various authorities. It then examined the admissibility and merits of Mr Kara's complaints.

On 15 April 2021 the Constitutional Court, sitting in plenary, delivered another judgment concerning an individual convicted of membership of the FETÖ/PDY on the basis of his use of ByLock. It principally examined an alleged violation of the principle of nullum crimen, nulla poena sine lege on the ground that the judicial interpretations as to the offence of membership of an armed terrorist organisation had not been foreseeable and that the conviction had been based on acts that did not constitute an offence. The applicant in that case argued in particular that the structure previously known as the ‘Gülen movement’ had been declared a terrorist organisation by a decision of the National Security Council dated 26 May 2016, with no mention of it being a terrorist organisation in the previous decisions, and that there was no evidence of any acts of violence before the said date that could suggest that the relevant structure was a terrorist organisation.

Similar to its approach in the Ferhat Kara case, the Constitutional Court first embarked on an examination of the characteristics and activities of the FETÖ/PDY. Reiterating that the clandestine activities of that organisation had already been the subject of investigations and prosecutions as of 2013, the Constitutional Court listed the incidents that had revealed the ulterior aims of this organisation, as noted in Ferhat Kara (see paragraph 172 above). It also referred to some other criminal proceedings initiated against suspected FETÖ/PDY members prior to the coup attempt, such as the proceedings brought in 2015 against the police officers who had refrained from taking any measures to prevent the murder of Hrant Dink despite their knowledge of the murder plans, allegedly in pursuance of the objectives of the organisation; the espionage proceedings brought in 2014 and 2015 against a number of public officials for bugging the residence and offices of the Prime Minister, as well as some high-level confidential meetings, and for wiretapping the encrypted telephones of senior State officials; and the many investigations launched regarding the allegations of the leaking of the questions for civil service entry and promotion exams to the members of the organisation.

The Constitutional Court then reviewed the relevant domestic law and practice in respect of the offence of membership of an armed terrorist organisation. It noted that, according to the settled case-law of the Court of Cassation, conviction for membership of an armed terrorist organisation would only follow where the courts could (i) establish the suspect's organic link with the organisation, based on the continuity, diversity and intensity of his or her activities; and (ii) demonstrate that he or she had acted knowingly and willingly within the organisation's hierarchical structure. Amongst many Court of Cassation judgments, the Constitutional Court cited the following passage from the Sixteenth Criminal Division (E.2019/521, K.2019/4679, 5 July 2019), as relevant:

The Constitutional Court also referred to a number of Court of Cassation judgments where acts such as attendance at conversation meetings (primarily before 2013), communicating (via telephone) with the district imam and other suspected members of the organisation, subscription to newspapers issued by the organisation and enrolment of children in schools affiliated with the organisation were considered as acts not going beyond mere sympathy and affiliation with the FETÖ/PDY, as they did not suggest an organic link to it or participation in its hierarchy.

The Constitutional Court noted that the concepts of ‘terror’ and ‘terrorism’ did not have universally accepted definitions; nevertheless, the courts were under an obligation to interpret the domestic law in a foreseeable manner that did not undermine the essence of the principle of nullum crimen, nulla poena sine lege when ruling on terror offences. The main issue in the case before it, from the perspective of the said principle, was whether acts performed in connection with the FETÖ/PDY in the period prior to the coup attempt could be taken as evidence of membership of that organisation, given that the FETÖ/PDY's criminal activities were not widely known in the relevant period.

In this connection, the Constitutional Court acknowledged that under Turkish law, the classification of a structure as a terrorist organisation was only possible by way of a judicial decision. It also reiterated, however, that prior to the characterisation of the FETÖ/PDY as a terrorist organisation by a judicial decision, the threat posed by the FETÖ/PDY had already been recognised in the decisions of the National Security Council, as well as in the 2014 National Security Policy Document, and many investigations had been launched before the coup attempt on suspicion of membership of the FETÖ/PDY.

The Constitutional Court further emphasised that the absence of a judicial ruling declaring an organisation ‘terrorist’ would not exclude the criminal liability of the members of such organisation, since an approach to the contrary would lead to impunity of all members in the period preceding the judicial ruling. That said, when assessing an individual's membership of the FETÖ/PDY it had also to be borne in mind that a significant proportion of the population had known and supported this organisation for many years as a religious group carrying out activities beneficial to society, such as in the field of education, without being aware of its illegal nature. An allegation as to the lack of knowledge of the true nature of the FETÖ/PDY would accordingly be examined in the light of the mistake provision under Article 30 of the Criminal Code (see paragraph 148 above), having regard to factors such as the accused's position in the organisation and the nature of the acts attributed to him or her. Moreover, acts performed prior to the period when the activities of the FETÖ/PDY had started being denounced at different levels of the State and among the public would not be considered by judicial authorities as falling within the scope of criminal ‘organisational’ activities, unless there were concrete facts and evidence suggesting that those acts had served the terrorist organisation, in view of their nature and substance. In other words, the courts would seek to establish, on the basis of concrete evidence, whether the acts at issue had been carried out with ‘organisational’ aims and within the framework of an ‘organisational’ relationship.

Turning to the facts before it, the Constitutional Court stated that the applicant Adnan Şen had not been convicted for the act of using ByLock, but because his use of ByLock had been considered to be evidence demonstrating his membership of the FETÖ/PDY. Based on the recognition that ByLock had been utilised by members of the FETÖ/PDY since early 2014 to conceal themselves and to ensure their organisational communication, the courts had found it established that the applicant had used that ‘organisational’ application for ‘organisational’ purposes, and therefore had full knowledge of the criminal intentions of that organisation. Consequently, the requisite conditions of continuity, diversity and intensity had been met. The applicant was also in a position to know the elements of the offence of membership of an armed terrorist organisation. The Constitutional Court emphasised that the courts' findings in the applicant's respect had not unduly extended the scope of the relevant offence in contravention of the principle of nullum crimen, nulla poena sine lege and had therefore been foreseeable.

The applicant stated that the offence for which he had been convicted, namely membership of an armed terrorist organisation, required the presence of a number of elements such as: the existence beyond reasonable doubt of an armed terrorist organisation; knowledge on the part of the suspect of the nature of that organisation; and the suspect's actual membership of that organisation, based on some qualitative requirements, as well as specific intent for the realisation of its aims. The applicant maintained that none of these elements had been established in his case and that, as a result, his prosecution for membership of an armed terrorist organisation had not been foreseeable. He therefore claimed that his conviction had been in contravention of Article 7 of the Convention.

He argued that the Gülen movement could not have been characterised as having been, beyond reasonable doubt, a ‘terrorist organisation’ at the time of the acts attributed to him, between 2014 and 2015. He claimed in this regard that following the indictment of F. Gülen on 31 August 2000 on the charges of founding and leading a terrorist organisation, all activities of the Gülen movement had been extensively investigated, resulting in acquittal of all the charges on 5 May 2006. When upholding the acquittal on 24 June 2008, the plenary criminal divisions of the Court of Cassation had confirmed that it had not been established that the accused, and the organisations allegedly linked to him, had harboured the goal of overthrowing the constitutional order, or had resorted to violence. From then on, the Gülen movement had maintained its activities without facing any other investigations until the end of 2013, when it was held responsible for several high-level political scandals. However, even at that point the Gülen movement was not categorised by the Government as a terrorist organisation.

Emphasising that under Turkish law only a court could decide whether a structure was a terrorist organisation, the applicant pointed out that there had been no final court judgments to this effect with respect to the Gülen movement at the time of his conviction by the Kayseri Assize Court on 21 March 2017. He further contended that neither in that judgment, nor in other judgments — against him or other suspects — that followed, were the elements of violence, pressure, intimidation or threat, which were essential to the definition of ‘terrorism’ under Turkish law, discussed in respect of the Gülen movement's activities preceding the coup attempt.

The applicant next argued that according to domestic law and practice, the offence of membership of an armed terrorist organisation necessitated not only the existence of an organisation that aimed at committing the offences listed in the Criminal Code, but also required that the organisation operate in a hierarchical structure and that the alleged members have performed acts of a certain continuity, diversity and intensity, none of which had been established in his case. He claimed that at no point in their judgments had the domestic courts laid out the hierarchical structure of the alleged armed terrorist organisation, other than in abstract and general terms, or his position therein. Many questions, such as whom he had taken orders from or to whom he had reported, with whom he had attended the meetings of the terrorist organisation, the offences he had committed on its behalf, and the degree of intensity and diversity of his involvement in the acts of the terrorist organisation had been left unanswered when establishing the elements of the offence attributed to him.

The applicant noted in this connection that even if it were to be accepted that the Gülen movement was a terrorist organisation, it was of the utmost importance to determine whether he had personally been aware of that fact at the time of the acts attributed to him, this state of awareness being one of the intrinsic elements of the offence of membership of an armed terrorist organisation. He contended that establishing the ultimate goal of an organisation was altogether different from establishing an individual's knowledge and acceptance of that goal. In arguing that he could not have been aware of the terrorist nature and intentions of the Gülen movement the applicant referred once again to the judgment of 2008 confirming the acquittal of F. Gülen of all crimes and to the many statements made by high-level Government officials publicly declaring their support for and appreciation of that movement over the years.

He further maintained that none of the acts attributed to him were such as to indicate membership of an armed terrorist organisation. The material elements of the offence of membership of an armed terrorist organisation were construed extremely broadly due to the very wide interpretation of the offence set out in in Article 314 § 2 of the Criminal Code, which had been wholly unforeseeable and had expanded the scope of criminal liability for the offence in question.

To the extent that his conviction was based on his alleged use of the ByLock application, an allegation which he denied, the applicant drew the Court's attention to the fact that the domestic courts had not examined the content of the messages that he had purportedly exchanged over the application, the instructions he had allegedly received, or how he had followed those instructions. He was, moreover, accused of having used that application only on six days, which fell short of the ‘continuity’ requirement for a hierarchical membership. He argued that, in any event, the domestic courts' finding that the application was exclusively designed for and used by members of the Gülen movement, and that its use could serve as proof of a person's hierarchical position within the Gülen movement, was unfounded. He stressed in this connection that the application had been downloaded some 600,000 times just from application stores — that is, without counting the downloads made from different APK sites — and that certain technical features of ByLock that had been portrayed as unique to that application to ensure its organisational use were in fact to be found in other comparable applications as well.

In the applicant's view, even if it were to be accepted that the evidence against him demonstrated his association with the Gülen movement, it still needed to be proven beyond reasonable doubt that he had acted with the requisite specific intent. The ‘specific intent’ in this context required the accused to have acted with the knowledge that the organisation had been established to commit certain offences and with the purpose of committing those offences. Establishing these points was particularly important in the present context bearing in mind that the Gülen movement was a social structure which had been supported by all segments of the society for decades. Holding ordinary members of that structure criminally liable for illegal activities carried out by the executives of the organisation, without establishing their individual intent, was contrary to the principle of individual criminal responsibility and amounted to collective punishment. The applicant claimed that he had been convicted essentially for allegedly associating with a community, some members of which had allegedly committed certain crimes.

The Government stated at the outset that although under Turkish law the designation of a structure as a ‘terrorist organisation’ was contingent upon a judicial finding to this effect, this was not a prerequisite for a conviction for membership of an armed terrorist organisation, as also noted by the Court in the case of Parmak and Bakır v. Turkey (nos. 22429/07 and 25195/07, § 71, 3 December 2019). According to domestic case-law, the founders, directors or members of a terrorist organisation could be held criminally liable from the date of the foundation of the organisation, or from the date on which it had transformed into a criminal organisation, even in the absence of a prior judicial decision proscribing it. To hold otherwise would mean that a person would go unpunished for the offences he had committed prior to a court decision designating a structure as a terrorist organisation, which would seriously imperil the fight against terrorism.

As to the relevance for the applicant's complaints under Article 7 of the confirmation of F. Gülen's acquittal by the Court of Cassation on 24 June 2008, and whether that acquittal had rendered his punishment for membership of FETÖ/PDY unforeseeable, the Government stressed that the scope of those proceedings had been limited to acts carried out and/or detected by the authorities prior to 31 August 2000, that is, the date on which the bill of indictment had been filed against F. Gülen. It therefore followed that the finding made in 2008 that, up to 2000, the impugned structure was not an armed terrorist organisation, did not necessarily render unforeseeable a later finding to the contrary, one that was based on acts that took place or evidence that surfaced after 2000.

The Government underlined in this connection that after 2013 many investigations into the illegal acts undertaken by the members of the FETÖ/PDY had been initiated, such as the ‘17–25 December investigations’ or the ‘MİT trucks investigations’. Furthermore, the National Security Council had declared the structure in question a ‘terrorist organisation’ in its meetings held between 26 February 2014 and 26 May 2016. The FETÖ/PDY had therefore started showing its true colours publicly by the time the applicant had committed the acts forming the basis of his conviction. They contended, accordingly, that the domestic courts' finding that the FETÖ/PDY was a terrorist organisation could reasonably have been foreseen by the applicant at the time of the acts on which his conviction rested, irrespective of F. Gülen's acquittal in 2008.

The Government next reviewed the constituent elements of the crime of membership of an armed terrorist organisation, which they claimed were formulated with sufficient precision in the relevant legislative framework and the case-law of the Court of Cassation, as referred to in detail in the judgments delivered in the applicant's respect. Based on those elements, the domestic courts had examined the FETÖ/PDY, including its purpose, functioning, socio-cultural and hierarchical structure, model of organisation and attempts to establish a parallel State structure, and had concluded that it was an armed terrorist organisation, albeit a sui generis one. In arriving at this conclusion, the domestic courts had taken into account the fact that the FETÖ/PDY had not aimed to come to power through legitimate methods, but had intended to abolish Parliament, the Government and other constitutional institutions by coercion, violence and other undemocratic methods, through its members that it had strategically placed within the State bureaucracy. The members placed in institutions authorised to use force, such as the army, the police and the MİT, had — during the coup attempt — used weapons belonging to the State against public institutions, the security forces and civilians with a view to bringing about their intended aims.

As for the applicant's specific situation, the Government stated that in view of the public awareness that had emerged, particularly after 2013, about the FETÖ/PDY's illegal activities, the domestic courts had found that the applicant had been in a position to know the ultimate purpose of the organisation, its structuring within the State institutions and the armed forces, and the fact that the members of the organisation, who had at their disposal every kind of weapon of the State, would use this force when necessary in line with the purpose of the organisation, given in particular his level of education, knowledge and professional experience. The courts had concluded against this background, and given the nature of the evidence against the applicant, that he had committed the acts attributed to him wilfully and with full knowledge of the illegal purposes of the FETÖ/PDY.

The Government referred in this connection to the domestic courts' reasons for finding why the use of the ByLock application was considered to meet all the constituent requirements of the offence of membership of an armed terrorist organisation, such as continuity, diversity, intensity and hierarchical link, irrespective of the content of the exchanges made over that application. The Government stressed that in case of secretive terrorist organisations, retrieving the contents of the messages in relation to individual users and establishing the context in which they were exchanged were often impossible because of the secure forms of the communications used; yet the judicial authorities had nevertheless duly established that ByLock was used exclusively by the executives and members of the terrorist organisation and had been developed by the FETÖ/PDY for secret intra-organisational communication. They explained that as an organisation based on secrecy, the FETÖ/PDY favoured face-to-face communication; however, where that was not possible, the organisation chose to conduct its communication via encrypted means. The friends' groups established in ByLock demonstrated the existence of a hierarchical structure and cell-type organisation, which were features of terrorist organisations. Based on those findings, the Government — while confirming at the hearing that the technical means by which the applicant had acquired the ByLock application were unknown to them — stated that it was not possible for a person who had no link to the organisation to download and use the ByLock application, and that ByLock users were already aware of the illegal purposes of the organisation, wanted those to be achieved and participated in organisational activities to that end. According to the Government, if a person had downloaded that application, which had been developed by the organisation and exclusively used by its members, and used it despite all technical difficulties, that showed that such a person fully submitted to the will of the organisation and adhered to its hierarchy. The mental element of the crime had, therefore, materialised in the applicant's case, who had established organisational communication with the members of the FETÖ/PDY via ByLock in line with the instructions of the organisational hierarchy, without ever calling into question those instructions. As such, the applicant could not benefit from the ‘mistake’ provision in Article 30 of the Criminal Code. Referring to the Court of Cassation's landmark judgments, the Government indicated that the use of ByLock would therefore be sufficient in itself for a conviction for membership of the FETÖ/PDY.

In response to the applicant's argument that he had not engaged in any criminally reprehensible conduct through his alleged use of ByLock, which was a lawful act, the Government contended that where membership of an armed terrorist organisation was proven, it was the act of membership itself that constituted the criminally reprehensible conduct. The applicant's use of ByLock was not a physical act forming part of the actus reus of the crime of which he was convicted. The domestic courts had not found the mere fact of the applicant's use of ByLock to amount to participation in an armed terrorist group as a member. The actus reus of the offence was rather the act of becoming part of the hierarchical structure of the organisation, by making himself available for commands and instructions. The applicant's use of ByLock was merely evidence demonstrating that he had become part of that structure. In other words, while the applicant had not become part of the hierarchical structure of the organisation by his use of ByLock, his use of that application was evidence that he had otherwise become a part of that hierarchy.

In these circumstances, it was immaterial to ask for the purposes of the ‘foreseeability’ requirement under Article 7 whether the applicant could have foreseen that the use of ByLock would be construed as evidence of the offence of membership of an armed terrorist organisation. According to the Government, the use in a criminal trial of a form of evidence, the use of which was unforeseen at the time of the acts in question, did not in itself raise issues under Article 7 of the Convention.

The Government argued that the finding that use of ByLock satisfied by itself the elements of the offence in question was not a novel interpretation; the Court of Cassation had long acknowledged, in the context of other terrorist organisations, that the performance of certain acts, by their nature, could in themselves constitute the offence of membership of an armed terrorist organisation. The Government referred in this connection to a judgment of the plenary criminal divisions of the Court of Cassation dated 26 June 2001, holding that the act of submitting a curriculum vitae to Hezbollah, an illegal armed organisation, had been considered as evidence of an organic link with the organisation, as it had demonstrated the accused's readiness to discharge the duties to be entrusted to him.

The Government indicated that the above arguments similarly applied, as relevant, in respect of the deposits that the applicant had made with Bank Asya, which was considered by the authorities to be a part of the financial structure of the terrorist organisation, and his membership of FETÖ/PDY-affiliated entities, which were used as corroborative evidence to prove his membership of that organisation. They acknowledged, however, that even ‘suspect’ deposits of funds with Bank Asya, which appeared to have been made upon the call of F. Gülen with the sole aim of benefiting the organisation, or membership of a trade union or association affiliated with the FETÖ/PDY, would not on their own suffice to prove membership of the FETÖ/PDY, but would only serve as corroborating elements when taken together with other substantial evidence, as in the present case.

The guarantee enshrined in Article 7 of the Convention, which is an essential element of the rule of law, occupies a prominent place in the Convention system of protection, as is underlined by the fact that no derogation from it is permissible under Article 15 of the Convention in time of war or other public emergency. It should be construed and applied, as follows from its object and purpose, in such a way as to provide effective safeguards against arbitrary prosecution, conviction and punishment (see Scoppola v. Italy (no. 2) [GC], no. 10249/03, § 92, 17 September 2009, and Del Río Prada, cited above, § 77, each with further references).

Article 7 of the Convention is not confined to prohibiting the retroactive application of criminal law to the disadvantage of an accused. It also embodies, more generally, the principle that only the law can define a crime and prescribe a penalty (nullum crimen, nulla poena sine lege) and the principle that criminal law must not be extensively construed to the detriment of an accused, for instance by analogy. From these principles it follows that an offence must be clearly defined in law. This requirement is satisfied where the individual can know from the wording of the relevant provision and, if need be, with the assistance of the courts' interpretation of it, what acts and omissions will make him criminally liable. When speaking of ‘law’, Article 7 alludes to the very same concept as that to which the Convention refers elsewhere when using that term, a concept which comprises written as well as unwritten law and implies qualitative requirements, notably those of accessibility and foreseeability (see, among other authorities, Streletz, Kessler and Krenz v. Germany [GC], nos. 34044/96, 35532/97, 44801/98, § 50, ECHR 2001-II, and Del Río Prada, cited above, § 91).

In any system of law, including criminal law, however clearly drafted a legal provision may be, there is an inevitable element of judicial interpretation. There will always be a need for elucidation of doubtful points and for adaptation to changing circumstances. Indeed, in the Convention States, the progressive development of the criminal law through judicial law-making is a well-entrenched and necessary part of legal tradition. Article 7 of the Convention cannot be read as outlawing the gradual clarification of the rules of criminal liability through judicial interpretation from case to case, provided that the resultant development is consistent with the essence of the offence and could reasonably be foreseen. The lack of an accessible and reasonably foreseeable judicial interpretation can lead to a finding of a violation of Article 7 rights. Were that not the case, the object and purpose of this provision — namely that no one should be subjected to arbitrary prosecution, conviction or punishment — would be defeated (see Del Río Prada, cited above, § 93, with further references).

The Court reiterates that, in principle, it is not its task to substitute itself for the domestic jurisdictions. It is primarily for the national authorities, notably the courts, to resolve problems of interpretation of domestic legislation. The Court's role is confined to ascertaining whether the effects of such an interpretation are compatible with the Convention (see, among others, Korbely v. Hungary [GC], no. 9174/02, §§ 72–73, ECHR 2008; and Kononov v. Latvia [GC], no. 36376/04, § 197, ECHR 2010).

The Court has stressed, however, that its powers of review must be greater when the Convention right itself, Article 7 in the present case, requires that there was a legal basis for a conviction and sentence (see, amongst others, Advisory opinion on the applicability of statutes of limitation to prosecution, conviction and punishment in respect of an offence constituting, in substance, an act of torture [GC], request no. P16-2021-001, Armenian Court of Cassation, § 71, 26 April 2022). Article 7 § 1 requires the Court to examine whether there was a contemporaneous legal basis for the applicant's conviction and, in particular, it must satisfy itself that the result reached by the relevant domestic courts was compatible with the object and purpose of that provision. To accord a lesser power of review to this Court would render Article 7 devoid of purpose (see Kononov, cited above, § 198, and Rohlena v. the Czech Republic [GC], no. 59552/08, § 52, ECHR 2015).

Lastly, the Court has found that the requirement of accessibility and foreseeability entails that, in principle, a measure can only be regarded as a penalty within the meaning of Article 7 where an element of personal liability on the part of the offender has been established. Accordingly, Article 7 requires, for the purposes of punishment, the existence of a mental link through which an element of liability may be detected in the conduct of the person who physically committed the offence (see G.I.E.M. S.r.l. and Others v. Italy [GC], nos. 1828/06 and 2 others, §§ 242 and 243, 28 June 2018). This requirement does not preclude the existence of certain forms of objective liability stemming from presumptions of liability, provided that they comply with the Convention. More specifically, a presumption should not have the effect of making it impossible for an individual to exonerate himself from the accusations against him (ibid., § 243).

The Court points out at the outset that it is not its task under Article 7 of the Convention to establish whether the applicant actually performed the acts imputed to him — in particular, whether he actually used the ByLock application, which he denies — or to rule on his individual criminal responsibility, those being primarily matters for the domestic courts (see Streletz, Kessler and Krenz, cited above, § 51; Navalnyye v. Russia, no. 101/15, § 58, 17 October 2017; and Khodorkovskiy and Lebedev v. Russia (no. 2), nos. 51111/07 and 42757/07, § 572, 14 January 2020). The Court's task is rather to consider, from the standpoint of Article 7, whether his conviction complied with the principles of legality and foreseeability enshrined in that provision.

The applicant in the present case was convicted of the offence of membership of an armed terrorist organisation. The Court will therefore first verify whether at the time of the acts attributed to him such an offence was clearly set out in domestic law.

It notes that the applicant's conviction was based on Article 314 § 2 of the Criminal Code, which provides for a sentence of five to ten years for those found to be members of an armed organisation formed with the purpose of committing one of the offences referred to in the first paragraph of that provision, i.e., offences against State security and the constitutional order (see paragraph 147 above).

Article 314 § 2 of the Criminal Code does not itself provide a definition of terrorism or terrorist organisation, which is set out in the Prevention of Terrorism Act. Under Section 1 of this Act, in its present wording, terrorism is defined as any kind of criminal act committed by use of force and violence, through one of the methods of pressure, terror, intimidation, oppression or threat, in pursuit of any of the aims listed in that same provision (see paragraph 149 above). Section 3 of the same Act further provides that the offences indicated in, inter alia, Article 314 of the Criminal Code are terrorist offences (ibid.). Section 7 of the Prevention of Terrorism Act in turn stipulates that those who become members of a terrorist organisation in order to commit crime in pursuance of the purposes set out under Section 1, by use of force and violence, and through the methods of pressure, terror, intimidation, oppression or threats, shall be punished in accordance with Article 314 of the Criminal Code (ibid.).

The legal framework governing the offence of membership of an armed terrorist organisation is complemented by the Court of Cassation's case-law, which provides further clarity on both the elements of an armed terrorist organisation, and that of the offence of membership of such an organisation (see paragraph 161 above). The Court of Cassation has specified that for the purposes of the offence set out in Article 314 § 2 of the Criminal Code, the ‘organisation’ is not an abstract gathering but one that is based on a hierarchical structure. In ascertaining the existence of the organisation, it has to be assessed whether it has, or had, sufficient members, tools and equipment to enable it to commit the intended offence, as required under Article 220 of the Criminal Code. In particular, it must be verified whether the organisation possesses, or possessed, a sufficient amount of arms to carry out its aims, or the means to access such arms.

The Court of Cassation has further clarified that conviction for membership of an armed terrorist organisation follows only where the accused's organic link with the armed organisation is established, based on the continuity, diversity and intensity of his or her activities, and where it is demonstrated that he or she acted knowingly and willingly within the organisation's hierarchical structure and embraced its objectives (see paragraph 184 above). It has moreover specified the mental element of the offence as being ‘direct intent and the aim or objective of committing a crime’. It therefore follows that a person taking part in an organisation has to know that it is one that commits, or aims to commit, crimes (ibid.), and has to possess a specific intent for the realisation of that purpose (see paragraph 83 above). Although the commission of an actual crime in connection with the organisation's activities and for the achievement of its aims is not required to establish the offence of membership of an armed terrorist organisation, the individual must nevertheless have made a concrete material or mental contribution to the organisation's actual existence or reinforcement (see paragraph 184 above).

Having regard to the legal provisions described above, and to their interpretation by the domestic courts, the Court considers that the offence of which the applicant was convicted is codified and defined under Turkish law, in keeping with the principle of legality under Article 7 of the Convention. Article 314 § 2 of the Criminal Code, particularly when read in conjunction with the Prevention of Terrorism Act and the case-law of the Court of Cassation, is, in principle, formulated with sufficient precision to enable an individual to know, if need be with appropriate legal advice, what acts and omissions would make him criminally liable.

The applicant nevertheless argued that his conviction was not compatible with Article 7 of the Convention, mainly for two reasons. He claimed that the FETÖ/PDY had not been recognised as an ‘armed terrorist organisation’ at the time of the acts attributed to him. He also argued that he had been convicted on the basis of lawful acts following an extensive interpretation of the relevant laws. The existence of the constituent elements of the offence of membership of an armed terrorist organisation as defined under the domestic law, in particular the mental element, had not been duly made out in his case. The Court will address these claims in turn.

The Court is acutely aware of the difficulties associated with the fight against terrorism and those that States encounter in the light of the changing methods and tactics used in the commission of terrorist offences (see Parmak and Bakır, cited above, § 77). It has, furthermore, already acknowledged the unique challenges faced by the Turkish authorities and courts in the context of their efforts against the FETÖ/PDY, having regard to the atypical nature of that organisation, which, according to the domestic authorities and courts, pursued its aims covertly rather than through traditional terrorist methods. The Court reiterates in this connection the finding it has made in a number of cases, and endorsed in the present case (see paragraph 213 above), that the attempted military coup in Türkiye disclosed the existence of a ‘public emergency threatening the life of the nation’ within the meaning of the Convention (see, for instance, Mehmet Hasan Altan, cited above, § 93, and Baş v. Turkey, no. 66448/17, § 115, 3 March 2020). Therefore, the urgency and severity of the situation that the authorities and courts had to grapple with in the aftermath of the coup attempt are recognised.

It should also be emphasised, however, that none of these considerations mean that the fundamental safeguards enshrined in Article 7 of the Convention, which is a non-derogable right that is at the core of the rule of law principle, may be applied less stringently when it comes to the prosecution and punishment of terrorist offences, even when allegedly committed in circumstances threatening the life of the nation. The Convention requires the observance of the Article 7 guarantees, including in the most difficult of circumstances.

The Court considers that it is up to the States to adapt their terrorism laws to be able to combat effectively the evolving threats of terrorism and non-traditional terrorist organisations, within the bounds of the nullum crimen, nulla poena sine lege principle. The offence of membership of an armed terrorist organisation under Turkish law was at the material time, and still remains, an offence of specific intent. The presence of some specific subjective elements is therefore a conditio sine qua non. Despite that, the finding by the domestic courts, through expansive interpretation of the applicable provisions of the Criminal Code and the Prevention of Terrorism Act, that the use of ByLock denoted membership of an armed terrorist organisation, without seeking to establish the presence in the applicant's specific case of the knowledge and intent required under the legal definition of the crime in domestic law, effectively attached objective liability to the use of ByLock. The Court is of the view that this expansive and unforeseeable interpretation of the law by the domestic courts had the effect of setting aside the constituent — notably the mental — elements of the offence and treating it as akin to an offence of strict liability, thereby departing from the requirements clearly laid down in domestic law. The scope of the offence was, therefore, extended to the detriment of the applicant in an unforeseeable manner, contrary to the object and purpose of Article 7.

The Court concludes, in the light of the foregoing, that there has been a violation of Article 7 of the Convention.

The applicant maintained his argument that the data pertaining to his use of ByLock had been collected unlawfully by the MİT and could therefore not be used as evidence to convict him, since the use of unlawful evidence was prohibited under domestic law. He argued that according to additional section 1 of the Law on Intelligence Services (see paragraph 145 above), information collected as part of intelligence activities could not be requested by judicial authorities for use as evidence in criminal proceedings, with the exception of certain specific offences which were not at issue in his case. Moreover, according to section 6 (2) of the same Law (see paragraph 144 above), a prior court order was required for the MİT to intercept communications via telecommunication networks, which had not been obtained before the MİT acquired the ByLock data. In holding that the MİT had acted lawfully, the domestic courts had erroneously relied on the MİT's powers set out in very broad terms in the first paragraph of section 6, ignoring the requirements under the second paragraph, and had failed to sufficiently explain why the rule under additional section 1 had not been observed.

The applicant further noted that in accepting the use of the ByLock data as lawful evidence in the criminal proceedings, the domestic courts — led by the Court of Cassation's landmark judgments — had based themselves on the fact that the examination and use of that data for judicial purposes had been authorised by the order issued by the Ankara Fourth Magistrate's Court on 9 December 2016 on the basis of Article 134 of the CCP. The applicant considered this finding to be problematic for a number of reasons. He claimed, in particular, that contrary to the domestic courts' reasoning, the analysis and use of the ByLock evidence for judicial purposes had predated the Ankara Fourth Magistrate's Court's order of 9 December 2016, as evidenced by the fact that he had been placed in pre-trial detention on 9 September 2016 for membership of the FETÖ/PDY on account of his use of ByLock. He gave similar examples from other proceedings initiated in relation to the use of ByLock throughout Türkiye and claimed that ByLock users were identified on the basis of the raw data collected by the MİT long before any judicial order. In the applicant's view, this meant that examination of the digital data and other ensuing measures were carried out within the scope of intelligence activities without any judicial warrant. This was in blatant disregard of the procedural safeguards laid down in domestic law, which had been put in place for the very purpose of providing protection against abuse and ensuring the integrity and reliability of the data seized. Despite this, the domestic courts had not subjected the admissibility and lawfulness of the main evidence to sufficient scrutiny.

In the applicant's view, this absence of judicial oversight of the collection and processing of the ByLock data had left them vulnerable to alterations and had made it impossible to verify their authenticity and integrity. This deficiency was further compounded by the fact that the MİT had not provided an account of the steps that it had taken to ensure the integrity of the data in a verifiable manner. In these circumstances, the ByLock data could neither be regarded as reliable nor conclusive. The applicant pointed in this connection to the alleged discrepancies between the different user lists prepared by the MİT, as well as between the number of downloads and that of individuals identified as users.

The applicant added that the CGNAT data and HTS records relied on by the Ankara Regional Court of Appeal to verify the accuracy of the ByLock data in his regard had similarly been unlawful and unreliable. He argued that whereas under the relevant legal framework Internet traffic data could be retained and stored for a maximum period of one year, the CGNAT data and HTS records submitted by the BTK to the appeal court in his respect had included information dating back more than one year. As for the reliability issue, the applicant referred in the first place to the alleged IP-based attribution challenges, claiming that the same IP address could be used by more than one person at a time, and also argued, relying on an expert report (see paragraph 131 above), that CGNAT data were in general not reliable indicators that a connection had been established by a certain individual with a certain target IP address. The same expert had also noted that the CGNAT data and HTS records in his case file did not conclusively suggest that he had connected to the ByLock server deliberately. The applicant further alleged that the BTK had fabricated log records by adding data to and removing data from the original traffic records that it had received from the network providers. By way of proof, he submitted some documents pertaining to another criminal investigation, where the missing target IP numbers in the original document issued by a service provider had been filled in by the BTK when transmitting that document to the trial court.

As regards his claims that he had not been able to duly challenge the evidence against him, the applicant maintained that despite being the decisive evidence for his conviction, and contrary to the requirement flowing from Article 134 § 4 of the CCP, a copy of the ByLock data pertaining to his alleged use of that application had not been disclosed to him or submitted to independent expert examination by the domestic courts. He could, therefore, neither verify the reliability of the data in question and refute the claims made by the MİT, nor use them to uncover any potentially exculpatory information and to contest the veracity of the ‘exclusive use’ argument. The ByLock reports made available to him instead contained very general, indirect and non-verifiable information that had been put together by officials whose ranks or functions had not been specified. What is more, those reports were highly cryptic and failed to explain how the relevant information had been put together from a technical point of view, which made them impossible to challenge in practice. The applicant further argued that the additional expert report commissioned by the Ankara Regional Court of Appeal merely summarised the findings already available in the case file, without any added value, and that his request for an independent examination of the raw data had been turned down. He contended that in these circumstances, his right to adversarial proceedings and equality of arms conferred by Article 6 of the Convention had been breached, as he had been at a substantial disadvantage vis-à-vis the prosecution. The applicant stressed that the circumstances of his case had to be distinguished from others similarly involving large amounts of electronic data, such as Rook v. Germany (no. 1586/15, 25 July 2019), where the lack of full disclosure of the data in the hands of the prosecution was not found to have breached the fair trial requirements under Article 6 § 1. He claimed that unlike in that case, the evidence used against him was not collected within the framework of a judicial procedure subject to independent oversight, and was thus inherently unreliable.

The applicant also complained that both the Ankara Regional Court of Appeal and the Court of Cassation had rejected his appeals without addressing his objections regarding issues that had been decisive for the outcome of the proceedings, including those of the lawfulness and admissibility of the ByLock evidence and the organisational nature of the ByLock application. He stressed the lack of satisfactory reasoning in respect of the finding that ByLock had been used by the Gülen movement exclusively, despite the centrality of that presumption to his conviction, as well as the failure of the domestic courts to duly establish his mental and material link to the serious offence that he had been charged with. The applicant argued that alongside him, thousands of others had been convicted of membership of an armed terrorist organisation as their alleged use of ByLock was deemed to be conclusive evidence of that crime in the landmark judgments of the Court of Cassation, despite the absence of any concrete evidence revealing the requisite link. According to the applicant, such unfettered arbitrariness on the part of the domestic courts, based not only on inadmissible but also totally irrelevant evidence and hypothetical findings, amounted to a blatant violation of fundamental rights and freedoms.

The applicant further underlined in this regard that the bank that he had dealt with and the trade union and association that he had been a member of had been operating with the permission and under the control of the State at the material time, which had also been ignored by the domestic courts.

The Government recalled at the outset that according to the subsidiarity principle that constituted the foundation of the Convention system, it was primarily for the domestic courts to assess the evidence available, and it was not for the Court to act as a court of ‘fourth instance’ by questioning the conclusions reached by domestic courts or to substitute its own views for their findings. Noting that the applicant's complaints under Article 6 mainly concerned the admissibility of the evidence indicating his use of ByLock and the assessment of the evidential value of the use of that application, the Government maintained that those matters had been duly reviewed by the domestic courts in a comprehensive manner. They further contended that the trial against the applicant had been fair overall and had been conducted in accordance with the principles of equality of arms and adversarial proceedings, and that he had been convicted on the basis of lawful and objective evidence. The Government then went on to address the specific claims raised by the applicant under this head.

They submitted that contrary to the applicant's arguments, the MİT had been mandated and authorised to collect the ByLock data by virtue of section 4 (1) (a) and (i) and section 6 (1) (d) and (g) of the Law on Intelligence Services (see paragraphs 143 and 144 above). The work conducted by the MİT in this respect was not an act of law enforcement or judicial investigation to collect evidence for use in criminal proceedings, but intelligence work carried out to detect terrorist threats before they materialised, which was a significant need in democratic societies and which did not require judicial oversight. They specified that the actual judicial process had started in December 2016 after the handover of the relevant digital data by the MİT to the judicial authorities, who had processed that data in keeping with Article 134 of the CCP and had provided judicial oversight.

The Government argued that the applicant had not put forth any concrete arguments as to why the relevant data could not be considered to be reliable and that, therefore, they should not be required to defend their reliability in the abstract. Nevertheless, they provided the Court with an account of the measures taken to ensure the reliability and authenticity of the ByLock data.

In this connection, the Government explained that the MİT had obtained the raw data from the ByLock server as a file automatically created by the MySQL software — an open-source relational database management system — without any human intervention. The hash value of the file was computed before its delivery to the judicial authorities to ensure the data integrity. Upon its subsequent receipt by the judicial authorities, the hard disk containing the raw ByLock data was subjected to examination pursuant to Article 134 of the CCP. Accordingly, it was copied by two appointed experts in accordance with the digital forensics standards, in the presence of a judge and recorded by camera, and one copy was sent to the KOM, and the other was secured at a safe deposit. Sufficient measures were therefore in place to ensure the integrity and reliability of the ByLock data. Moreover, the judicial authorities had the power to put the data in their possession to the test and to assess their authenticity and reliability.

The Government further explained that the action carried out by the MİT and subsequently the KOM had been limited to rendering the raw data intelligible in order to be able to extract meaningful information from them — as the raw data file generated automatically by the MySQL was not readable without further processing with the assistance of an interface program — and had not involved any modification of their content. The analysis carried out by the MİT in this respect had not been subject to any judicial authorisation or oversight, as it remained within the domain of intelligence activities. However, the fact that the end-product retrieved separately by the MİT and by the KOM matched was proof that no manipulation of the raw data had taken place. It was further observed that in many investigations subsequently carried out, the statements given by the accused regarding the usernames, passwords and roster information matched the ByLock data retrieved by the MİT and the judicial authorities.

However, in the Government's opinion, the most telling indication of the integrity of the raw ByLock data was that the CGNAT data — which gave information about the date, the number of times and the address from which a connection had been made to the target IP address of the ByLock server — included in the applicant's case file at the appeal court stage tallied with his ByLock data. The Government contended that there was no question regarding the reliability of CGNAT data per se, as this was data produced by the service providers' systems following the generation of traffic flow and after the calculation of the hash value, and thus were not corruptible. What is more, the appeal court had verified the CGNAT data against the HTS records — which indicated, inter alia, the call history and the times and durations of the calls made — and had also appointed an independent digital forensics expert to examine all the available data. The Government pointed out that the applicant had had the right under Article 68 of the CCP to request the hearing of this expert in the trial, yet he had not exercised that right. Nor had he explained why he objected to that expert and requested the re-examination of the evidence by a panel of three experts instead.

The Government further contested the applicant's argument that he had not been able to duly challenge the evidence against him. They argued that the applicant's use of ByLock had been established on the basis of various reports drawn up by the police, the BTK and the aforementioned independent expert, and that all of those reports had been made available to him in keeping with the principles of equality of arms and adversarial proceedings. They stressed that the applicant's access to the investigation file had not been restricted in any way. They moreover added that the applicant could also challenge the finding in the landmark judgments of the Court of Cassation regarding the ‘exclusive use’ of ByLock by members of the FETÖ/PDY, which he had failed to do.

As for the applicant's claim that he had not been able to obtain a copy of the original or raw ByLock data, the Government argued that whereas the procedure set out under Article 134 of the CCP for the seizure of digital material required the sharing with the suspect of the copies of the material seized, that requirement only applied where the suspect was the owner of the computer, computer program or the log from which the data had been seized. The data at issue in the present case did not, however, belong to the applicant, but had been obtained from the ByLock server. The Government stressed that the ByLock data obtained by the MİT contained millions of data items relating to more than a hundred thousand users. Moreover, it was not intelligible in the form in which it had been collected. Information pertaining to a user was not found in one place but was scattered in different tables, making it impossible to extract the raw data for individual users, and the authorities had therefore had to develop an interface program to make the data meaningful in relation to each user. In these circumstances, the disclosure of the entire body of raw data to the applicant would entail sharing data relating to all users, thereby creating a security risk and potentially prejudicing the investigations, not to mention the interference that it would constitute with the privacy rights of other users. Moreover, special software had to be used in order to render the raw data meaningful. The Government noted that in any event, the applicant had failed to explain how his inability to obtain a copy of the raw data in its entirety had put him at a disadvantage and how this data would have impacted the decision to be delivered in his respect.

The Government lastly contended that the domestic courts' interpretations and conclusions regarding the evidential value of the ByLock evidence, involving extensive evaluations of the technical and organisational aspects of ByLock, did not entail any manifest error or arbitrariness and that they had duly reasoned their judgments. They claimed in this regard that the domestic judgments in the present case were based on findings of fact and the relevant case-law of the Court of Cassation, which had established that ByLock had been used exclusively by the FETÖ/PDY. Having regard to the constraints under which the judicial system was operating at the material time as noted by the Constitutional Court in its Aydın Yavuz and Others judgment (as noted in Baş, cited above, § 93) and the derogation in place, it was consistent with Article 6, and strictly required within the meaning of Article 15 of the Convention, for domestic courts to rely on earlier case-law in this manner without engaging in a fresh examination of the matter themselves — provided that it was open to an accused to challenge those findings.

Accordingly, when the Ankara Regional Court of Appeal had deemed the evidence leading to the applicant's conviction at first instance — that is, ByLock user reports prepared on the basis of the raw data — to be insufficient, it had requested complementary reports from the BTK concerning the applicant's CGNAT data and HTS records, and had thus verified the finding regarding the applicant's use of ByLock in a manner consistent with the Court of Cassation's case-law. The appeal court had also responded to the applicant's claims concerning the unlawfulness of the evidence at issue, and had engaged in a detailed assessment of the elements of the offence of membership of an armed terrorist organisation and discussed why the use of ByLock was deemed sufficient to prove membership of that organisation. This finding was, moreover, supported by other corroborating evidence. The Court of Cassation had in turn endorsed the appeal court's duly reasoned judgment, which the appellate courts were allowed to do under the Court's case-law (see García Ruiz v. Spain [GC], no. 30544/96, § 26, ECHR 1999-I).

To the extent that the applicant complained that the impugned evidence was insufficient to sustain a conviction, the Government reiterated that the Court was not a court of fourth-instance before which an applicant could raise issues of the sufficiency of evidence. They emphasised that, as per Article 217 of the CCP, an imputed offence could be proven by any evidence obtained lawfully, including circumstantial evidence, and that it was primarily for the domestic courts to assess the evidence and reach the necessary conclusions in the context of criminal proceedings.

The Court has established above, under Article 7 of the Convention, that the applicant's conviction for membership of an armed terrorist organisation was based on an expansive and unforeseeable interpretation of the relevant domestic law. It found that this interpretation, whereby the domestic courts effectively imputed objective liability to the users of ByLock, had the effect of assuming instead of establishing the constituent elements of the offence at issue as set out under the relevant domestic law and practice. It therefore contravened the object and purpose of that provision to provide effective safeguards against arbitrary prosecution, conviction and punishment.

The applicant's complaints regarding his conviction on the basis of his alleged use of ByLock are not however limited to the question of the conformity of such conviction with the principles enshrined in Article 7 of the Convention. As set out in paragraph 273 above, the applicant also complained under Article 6 § 1 of the alleged irregularities in the collection and admission in evidence of the ByLock data, as well as the difficulties he encountered in challenging them and the inadequacy of the reasoning in the courts' decisions vis-à-vis that evidence, producing an arbitrary outcome. To the extent that the applicant's complaints relate to the deficiencies in the domestic proceedings in the establishment of the material and mental elements of the offence of membership of an armed terrorist organisation on the basis of his alleged use of ByLock, that matter has already been dealt with under Article 7 and no separate issue arises under Article 6 § 1. However, the applicant has raised some distinct fair trial issues, particularly of a procedural nature, that do not fall to be addressed under Article 7. The Court is therefore called upon to determine under Article 6 § 1 whether the applicant's defence rights were prejudiced on account of the various shortcomings alleged.

It is not for the Court to deal with alleged errors of law or fact committed by the national courts unless and in so far as they may have infringed rights and freedoms protected by the Convention (see, amongst others, García Ruiz, cited above, § 28, and Perez v. France [GC], no. 47287/99, § 82, ECHR 2004-I), for instance where it can, exceptionally, be said that they are constitutive of ‘unfairness’ incompatible with Article 6 of the Convention. While this provision guarantees the right to a fair trial, it does not lay down any rules on the admissibility of evidence or the way in which evidence should be assessed, these being primarily matters for regulation by national law and the national courts (see Moreira Ferreira v. Portugal (no. 2) [GC], no. 19867/12, § 83, 11 July 2017).

It is therefore not the role of the Court to determine, as a matter of principle, whether particular types of evidence — for example, evidence obtained unlawfully in terms of domestic law — may be admissible or, indeed, whether the applicant was guilty or not. The question which must be answered is whether the proceedings as a whole, including the way in which the evidence was obtained, were fair (see Bykov v. Russia [GC], no. 4378/02, § 89, 10 March 2009, and the cases cited therein). It must be examined, inter alia, whether the applicant was given the opportunity to challenge the evidence and to oppose its use. From the perspective of the rights of the defence, issues under Article 6 may arise in terms of whether the evidence produced for or against the defendant was presented in such a way as to ensure a fair trial (see Erkapić v. Croatia, no. 51198/08, § 73, 25 April 2013), because a fair trial presupposes adversarial proceedings and equality of arms; thus, possible flaws in the process of administration of evidence may be examined under Article 6 § 1 (see Mirilashvili v. Russia, no. 6293/04, § 157, 11 December 2008). In addition, the quality of the evidence must be taken into consideration, including whether the circumstances in which it was obtained cast doubt on its reliability or accuracy (see Bykov, cited above, § 90). While no problem of fairness necessarily arises where the evidence obtained is unsupported by other material, it may be noted that where the evidence is very strong and there is no risk of its being unreliable, the need for supporting evidence is correspondingly weaker (ibid.). In undertaking this examination, the Court also has regard to the state of the other evidence in the case file and attaches weight to whether the evidence in question was or was not decisive for the outcome of the proceedings (see ibid., and Gäfgen v. Germany [GC], no. 22978/05, § 164, ECHR 2010).

Issues such as the weight attached by the national courts to particular items of evidence or to findings or assessments submitted to them for consideration are not for the Court to review. The Court should not act as a fourth-instance body and will therefore not question under Article 6 § 1 the national courts' assessment unless their findings can be regarded as arbitrary or manifestly unreasonable (see Bochan v. Ukraine (no.2) [GC], no. 22251/08, § 61 and 62, ECHR 2015; see also the cases cited therein: Dulaurans v. France, no. 34553/97, §§ 33–34 and 38, 21 March 2000; Khamidov v. Russia, no. 72118/01, §§ 170-75, 15 November 2007; and Anđelković v. Serbia, no. 1401/08, §§ 24–29, 9 April 2013; as well as the application of this case-law in more recent judgments: Moreira Ferreira, cited above, §§ 83–100; Pavlović and Others v. Croatia, no. 13274/11, § 49, 2 April 2015; Tsanova-Gecheva v. Bulgaria, no. 43800/12, § 91, 15 September 2015; Navalnyy and Ofitserov v. Russia, nos. 46632/13 and 28671/14, §§ 103-20, 23 February 2016; Navalnyye, cited above, §§ 81–84; and Ballıktaş Bingöllü v. Turkey, no. 76730/12, §§ 78–84, 22 June 2021). It transpires from this case-law that a domestic judicial decision cannot be qualified as arbitrary to the point of prejudicing the fairness of proceedings unless no reasons are provided for it or if the reasons given are based on a manifest factual or legal error committed by the domestic court, resulting in a ‘denial of justice’ (see Moreira Ferreira, cited above, § 85).

The Court reiterates in this regard that according to its established case-law reflecting a principle linked to the proper administration of justice, judgments of courts and tribunals should adequately state the reasons on which they are based. The extent to which this duty to give reasons applies may vary according to the nature of the decision and must be determined in the light of the circumstances of the case (see García Ruiz, cited above, § 26). Without requiring a detailed answer to every argument advanced by the complainant, this obligation presupposes that parties to judicial proceedings can expect to receive a specific and explicit reply to the arguments which are decisive for the outcome of those proceedings (see, among other authorities, Moreira Ferreira, cited above, § 84, and the cases cited therein). It must be clear from the decision that the essential issues of the case have been addressed (see Taxquet v. Belgium [GC], no. 926/05, § 91, ECHR 2010). In view of the principle that the Convention is intended to guarantee not rights that are theoretical or illusory but rights that are practical and effective, the right to a fair trial cannot be seen as effective unless the requests and observations of the parties are truly ‘heard’, that is to say, properly examined by the tribunal (see Ilgar Mammadov v. Azerbaijan (no. 2), no. 919/15, § 206, 16 November 2017; Carmel Saliba v. Malta, no. 24221/13, § 65, 29 November 2016, with further references therein; Ayetullah Ay v. Turkey, nos. 29084/07 and 1191/08, § 127 and 195, 27 October 2020; and Pişkin, cited above, §§ 147, 149 and 151).

It is further reiterated that a fundamental aspect of the right to a fair trial is that criminal proceedings, including the elements of such proceedings which relate to procedure, should be adversarial and that there should be equality of arms between the prosecution and defence. The right to an adversarial trial means, in a criminal case, that both prosecution and defence must be given the opportunity to have knowledge of and comment on the observations filed and the evidence adduced by the other party (see, for instance, Murtazaliyeva v. Russia [GC], no. 36658/05, § 91, 18 December 2018). The accused must have the opportunity to organise his or her defence in an appropriate way and without restriction as to the possibility of putting all relevant defence arguments before the trial court and thus of influencing the outcome of the proceedings (see Rook, cited above, § 56). The facilities which everyone charged with a criminal offence should enjoy include the opportunity to acquaint him or herself, for the purposes of preparing his or her defence, with the results of investigations carried out throughout the proceedings (ibid., § 57).

The right to an adversarial trial also requires, in a criminal case, that the prosecution authorities disclose to the defence all material evidence in their possession for or against the accused (see Rowe and Davis v. the United Kingdom [GC], no. 28901/95, § 60, ECHR 2000-II). The term ‘material evidence’ cannot be construed narrowly, in the sense that it cannot be confined to evidence considered as relevant by the prosecution. Rather, it covers all material in the possession of the authorities with potential relevance, also if not at all considered, or not considered as relevant (see Rook, cited above, § 58). Failure to disclose to the defence material evidence which contains such particulars as could enable the accused to exonerate him- or herself or have his or her sentence reduced would constitute a refusal of facilities necessary for the preparation of the defence (see Natunen v. Finland, no. 21022/04, § 43, 31 March 2009, and Matanović v. Croatia, no. 2742/12, § 157, 4 April 2017).

However, the entitlement to disclosure of relevant evidence is not an absolute right. In any criminal proceedings there may be competing interests, such as national security or the need to keep secret police methods of investigation of crime, which must be weighed against the rights of the accused (see, for the relevant principles, Jasper v. the United Kingdom [GC], no. 27052/95, § 52, 16 February 2000). In some cases, it may be necessary to withhold certain evidence from the defence so as to preserve the fundamental rights of another individual or to safeguard an important public interest. That said, in principle, only such measures restricting the rights of the defence which are strictly necessary are permissible under Article 6 § 1. Moreover, in order to ensure that the accused receives a fair trial, any difficulties caused to the defence by a limitation on its rights must be sufficiently counterbalanced by the procedures followed by the judicial authorities (ibid., with further references). In making its assessment of the relevant procedural guarantees, the Court must have regard to the importance of the undisclosed material and its use in the trial (see Matanović, cited above, § 155). The accused may, however, be expected to give specific reasons for his request and the domestic courts are entitled to examine the validity of these reasons (ibid., § 157, and Rook, cited above, § 59).

The Court reiterates that electronic evidence attesting to an individual's use of an encrypted messaging system that was allegedly designed by a terrorist organisation for the purposes of its internal communications may, in principle, be very important in the fight against terrorism or other organised crime (see, for a similar finding, Akgün, cited above, § 167). However, while the fight against terrorism may necessitate resorting to such evidence, the right to a fair trial, from which the requirement of the proper administration of justice is to be inferred, applies to all types of criminal offence, from the most straightforward to the most complex. The right to the fair administration of justice holds so prominent a place in a democratic society that it cannot be sacrificed for the sake of expediency (see Ramanauskas v. Lithuania [GC], no. 74420/01, § 53, ECHR 2008) and the evidence obtained, whether electronic or not, may not be used by the domestic courts in a manner that undermines the basic tenets of a fair trial.

Accordingly, and despite the specific features of the criminal proceedings at issue — both in terms of the context in which they were conducted and the nature and scope of the main evidence at their origin, which entailed a high volume of encrypted electronic data relating to thousands of other individuals —, the domestic courts were required to take adequate measures to ensure the overall fairness of the proceedings against the applicant. As demonstrated above, this they failed to do. In the Court's view, the domestic courts' failure to put in place appropriate safeguards vis-à-vis the key piece of evidence at issue to enable the applicant to challenge it effectively, to address the salient issues lying at the core of the case and to provide reasons justifying their decisions was incompatible with the very essence of the applicant's procedural rights under Article 6 § 1. These failings had the effects of undermining the confidence that courts in a democratic society must inspire in the public and of breaching the fairness of the proceedings (see Ayetullah Ay, cited above, § 192).

In the Court's view, the foregoing considerations are sufficient to lead to the conclusion that the criminal proceedings against the applicant fell short of the requirements of a fair trial in breach of Article 6 § 1 of the Convention.

The Court notes at the outset that the right to a fair trial, as protected by Article 6 of the Convention does not feature among the non-derogable rights listed in Article 15 § 2. It is therefore a derogable right. Thus, the breach of certain procedural safeguards in criminal proceedings which is susceptible of giving rise to a violation of that provision under ‘normal’ circumstances may still be regarded as compatible with that provision in time of war or other public emergency threatening the life of the nation, provided that the conditions stipulated in Article 15 § 1 are met, that is to say that it was strictly required by the exigencies of the situation and consistent with the State's other obligations under international law.

The Court reiterates in this regard that it falls to each Contracting State, with its responsibility for ‘the life of [its] nation’, to determine whether that life is threatened by a ‘public emergency’ and, if so, how far it is necessary to go in attempting to overcome the emergency. By reason of their direct and continuous contact with the pressing needs of the moment, the national authorities are in principle in a better position than the international judge to decide both on the presence of such an emergency and on the nature and scope of derogations necessary to avert it. Accordingly, in this matter a wide margin of appreciation should be left to the national authorities (see Ireland v. the United Kingdom, 18 January 1978, § 207, Series A no. 25).

Nevertheless, Contracting Parties do not enjoy an unlimited power of appreciation. The Court, which is responsible for ensuring the observance of the States' engagements under Article 19 of the Convention, is empowered to rule on whether the States have gone beyond the ‘extent strictly required by the exigencies’ of the crisis. The domestic margin of appreciation is thus accompanied by European supervision (ibid.). At the same time, in exercising its supervision the Court must give appropriate weight to such relevant factors as the nature of the rights affected by the derogation, the circumstances leading to, and the duration of, the emergency situation (see Brannigan and McBride v. the United Kingdom, 26 May 1993, § 43, Series A no. 258-B).

The Court considers that its supervision in this framework must be guided primarily by the rule of law, which is one of the fundamental principles of a democratic society that is inherent in all the Articles of the Convention, and which is expressly referred to in the Preamble to the Convention (see Grzėda v. Poland [GC], no. 43572/18, § 339, 15 March 2022, with further references). A derogation under Article 15, even if it may be justified by the circumstances surrounding it, does not have the effect of dispensing the States from the obligation to respect the principle of the rule of law and its attendant guarantees. As the Court has previously pointed out, even in the context of a state of emergency, the fundamental principle of the rule of law must prevail (see, for instance, Pişkin, cited above, § 153, and Ahmet Hüsrev Altan, cited above, § 165; see also the Venice Commission opinion noted in paragraph 202 above). Similarly, a valid derogation under Article 15 does not give the State authorities carte blanche to engage in conduct that may lead to arbitrary consequences for individuals. The Court reiterates in this regard that arbitrariness on the part of State authorities entails a negation of the rule of law (see, mutatis mutandis, Al-Dulimi and Montana Management Inc. v. Switzerland [GC], no. 5809/08, § 145, 21 June 2016) and may not be tolerated, whether in respect of substantive or procedural rights (see for a case to this effect not relating to Article 15 of the Convention, Muhammad and Muhammad v. Romania [GC], no. 80982/12, § 118, 15 October 2020). As it has often noted, the rule of law and the avoidance of arbitrary power are principles underlying the Convention and, in the judicial sphere, they serve to foster public confidence in an objective and transparent justice system (see Taxquet, cited above, § 90). Accordingly, when determining whether a derogating measure that encroaches upon the right to a fair trial was fully justified in that it was strictly required by the exigencies of the situation, the Court must also examine whether adequate safeguards were provided against abuse and whether the measure undermined the rule of law.

The Court further reiterates that Article 6 should not be applied in such a manner as to put disproportionate difficulties in the way of the authorities in taking effective measures to counter terrorism or other serious crimes in discharge of their duty to protect the right to life and the right to bodily security of members of the public (see Ibrahim and Others v. the United Kingdom [GC], nos. 50541/08 and 3 others, § 252, 13 September 2016). It refers, in this regard, to its considerations under Article 7 concerning the difficulties faced by the States in their struggle against terrorism in view of the dynamic nature of this threat and, more specifically, the serious predicament faced by Türkiye as a result of the attempted coup and the allegedly unorthodox nature of and methods employed by the FETÖ/PDY. The Court is also mindful of the heavy burden faced by the judicial authorities in Türkiye in the aftermath of the coup attempt. It refers in this connection to the findings of the Constitutional Court, in the case of Aydın Yavuz and Others in the context of the right to liberty and security, that the judicial and investigating authorities had had to handle an unforeseeably heavy workload, given that they had suddenly been required to initiate and conduct investigations in respect of tens of thousands of suspects because of the unexpected situation brought about by the coup attempt. Furthermore, thousands of judges and prosecutors had been dismissed from office for alleged connections with that organisation, some of whom have applications pending before the Court (see Baş, cited above, §§ 92 and 93).

Turning to the specific facts of the present case, the Government invited the Court to examine the applicant's complaints under Article 6 with due regard to the derogation notification and referred, in a general manner, to all the legislative decrees enacted during the state of emergency. However, when it came to substantiating their arguments regarding the fair trial issues raised by the applicant in relation to the ByLock evidence, they did not in any way claim that those issues resulted, even indirectly, from the specific measures adopted by the aforementioned legislative decrees (compare Pişkin, cited above, §§ 121-25 and 153).

The Government did however submit that the reliance of the domestic courts in the applicant's case on the Court of Cassation's landmark judgments as regards the ‘exclusivity’ argument, without engaging in a fresh examination of this matter themselves, was consistent with the exigencies of the state of emergency and strictly required within the meaning of Article 15 of the Convention, given the constraints under which the judiciary was operating at the material time (see paragraph 297 above). The Court notes, however, that the problem it has identified under Article 6 § 1 was not the fact that the domestic courts relied on the precedent created by the landmark judgments of the Court of Cassation when examining the applicant's case. It was rather that the applicant was deprived of adequate means to challenge those findings, the importance of which the Government also acknowledged in their relevant submissions (ibid.). In this regard, neither the Government nor the domestic courts — including the Court of Cassation in its landmark judgments — claimed that any specific measures had been taken, or been required, at the relevant period to restrict the rights of the defence in that respect. What is more, there is no indication in the landmark judgments of the Court of Cassation that the ‘exclusivity’ argument at issue had been developed by reason of the special circumstances of the state of emergency.

The Court observes in this connection that none of the domestic courts involved in the applicant's case examined the fair trial issues relating to the ByLock evidence from the standpoint of Article 15 of the Convention or Article 15 of the Turkish Constitution, which similarly regulates derogations in times of emergency (see paragraph 141 above), or mentioned, even as a contextual factor framing their approach to those issues, the threats or difficulties giving rise to the state of emergency. The Government did not claim otherwise. Nor did they submit any other judicial rulings delivered at the relevant period in which the domestic courts had in fact engaged in an assessment of the implications of the state of emergency and the derogation for the fair trial issues examined in the present case, similar to the judgments in which the Constitutional Court had closely examined those matters in the context of the right to liberty and security (see paragraph 351 above, as well as Baş, cited above, §§ 92 and 93) and the right to legal assistance (see paragraph 209 above). The Court further notes the Government's statement made as part of their submissions under Article 6 § 3 (c) of the Convention that ‘the state of emergency had not been determinative in the decisions of the judicial authorities, and that judicial activities were carried out by [their] own principles and rules’, as evidenced by the fact that the applicant had been released from detention by the first-instance court on 21 March 2017 — that is, while the state of emergency was still in effect (see paragraph 209 above). The Court acknowledges the limited significance of this statement for the purposes of the present examination, given the specific context in which it was made and the fact that the Article 6 § 3 (c) complaint will not be examined in the present judgment for the reasons indicated below (see paragraphs 366–367). It nevertheless considers this statement to be consistent with the Government's observations regarding the fair trial issues raised by the applicant in relation to the ByLock evidence that the criminal proceedings had been conducted by the domestic courts in a manner that duly observed the applicant's procedural rights (see the Government's observations in paragraphs 289–299 above and, in particular, paragraph 289).

The Court is mindful that it is not its role to substitute its view as to what measures were most appropriate or expedient in dealing with an emergency situation for that of the State authorities, which have direct responsibility for establishing the balance between effectively combatting terrorism on the one hand and respecting individual rights on the other (see Brannigan and McBride, cited above, § 59). It further accepts that the difficulties facing Türkiye in the aftermath of the attempted military coup of 15 July 2016 are undoubtedly a contextual factor which must be taken into account. The Court also notes, however, that in contrast to their submissions in relation to Article 6 § 3 (c) of the Convention (see paragraph 209 above), the Government have not adduced any detailed reasons before it as to whether the specific fair trial issues identified above originated in the special measures taken during the state of emergency and, if so, why they were necessary to avert it or whether they were a genuine and proportionate response to the emergency situation (see A. and Others v. the United Kingdom [GC], no. 3455/05, § 184, ECHR 2009, and Alparslan Altan, cited above, §§ 116-18). In these circumstances, the Court considers that the limitations on the applicant's fair trial rights at issue — which, as indicated in paragraph 345 above, were incompatible with the very essence of his procedural rights under Article 6 § 1 and had the effect of undermining the confidence that courts in a democratic society must inspire in the public — cannot be treated as having been strictly required by the exigencies of the situation. A finding to the contrary in such circumstances would negate the safeguards provided by Article 6 § 1 of the Convention, which must always be construed in the light of the rule of law (see Nicolae Virgiliu Tănase v. Romania [GC], no. 41720/13, § 192, 25 June 2019).

The Court concludes, in view of the above considerations, that there has been a violation of Article 6 § 1 of the Convention on the facts of the present case.

The applicant submitted at the outset that the judicial bodies' decision to convict him of a terrorism offence and to sentence him to six years and three months' imprisonment, on the grounds, inter alia, of his membership of a trade union and an association had constituted a direct, clear, and severe interference with his rights guaranteed under Article 11 of the Convention. In that regard, the applicant asserted that, contrary to the Government's allegation, the trial court had not accorded any special weight to the individual pieces of evidence that formed the basis of its decision to convict him. Moreover, even the Government themselves had not denied that his membership of the impugned trade union and association directly related to his exercise of fundamental rights under both domestic and international law. Accordingly, the Government's argument that there had been no interference was untenable.

As regards the question whether the interference was justified, the applicant pointed out, firstly, that the Government did not contest that both the trade union and the association in question had been established and had operated in accordance with the laws of Türkiye. Indeed, Aktif Eğitim-Sen had been a trade union representing public servants in the field of education. Kayseri Voluntary Educators Association had been dedicated to providing ‘voluntary educational services’ to children. In this context, the applicant had given free chess courses to children. Furthermore, the applicant stated that by becoming a member of the trade union and association, he had not shown any intent or motive to commit a terrorist offence. More importantly, the trial court had not mentioned or even implied that he had undertaken or taken part in any illegal activity. Nor had the trade union or the association at issue ever been involved in any such activity. There was therefore no rational link between his memberships of these bodies and the terrorism offence of which he had been convicted.

In view of the foregoing considerations, the applicant took the view that the trial court's interpretation of Article 314 § 2 of the Criminal Code — under which he had been found guilty — was so vague and arbitrary that the interference with his rights under Article 11 of the Convention had not been prescribed by law.

Lastly, the applicant stated that the facts of the present case were entirely different from those of Ayoub and Others v. France (nos. 77400/14 and 2 others, 8 October 2020), on which the Government relied, and he asked the Court to dismiss that argument.

Referring to their submissions concerning the ByLock application under Articles 6 and 7 of the Convention, the Government contended that there had been no interference with the applicant's rights under Article 11 because the decisive evidence relied on for his conviction had been his use of ByLock. Moreover, the trial court had taken into account the fact that the applicant had deposited money with Bank Asya upon the instructions of the ringleader of the FETÖ/PDY along with the fact that he had been a member of a trade union and an association which had been shut down by Legislative Decree no. 667 in the context of the measures taken during the state of emergency. Considering that the trade union and the association in question had the purpose of carrying out the FETÖ/PDY's organisational activities under a legal appearance, the judicial bodies had merely relied on the applicant's membership thereof as corroborative evidence. Therefore, when taken as a whole, the elements of evidence relied on by the trial court for the applicant's conviction had not contradicted each other; on the contrary, they had complemented and confirmed one another. That being the case, the trial court had established that the material and mental elements of the offence of which the applicant had been convicted had been made out. Accordingly, the applicant had not been punished for simply being a member of an association or a trade union, nor had he faced any obstruction in the enjoyment of his right to respect for his freedom of assembly and association.

If the Court were to consider that there had been an interference with the applicant's rights under Article 11 of the Convention, the Government took the view that the interference had been prescribed by law, namely Article 314 § 2 of the Criminal Code and the case-law of the Court of Cassation. In that regard, the Government submitted that the well-established case-law of the Court of Cassation demonstrated that membership of a trade union or an association would not, without more, be sufficient to convict a person of being a member of an armed terrorist organisation, provided that the acts committed by the accused did not meet the continuity, diversity and intensity criteria or otherwise indicate his or her involvement in the hierarchical structure of the armed terrorist organisation. However, the case-law of the Court of Cassation demonstrated that it was appropriate to convict an individual who had used ByLock, had deposited money with Bank Asya in accordance with the instructions of the FETÖ/PDY and who had been a member of a trade union that had been considered to be affiliated with the FETÖ/PDY.

As regards the purpose of the alleged interference, the Government argued that this had been the protection of national security and public safety and the prevention of disorder or crime, given that the FETÖ/PDY — of which the applicant had been found to have been a member — had attempted to overthrow the Republic of Türkiye. The Government further stressed that any interference had been necessary in a democratic society, arguing that the trial court had approached the applicant's membership of the trade union and the association in question with caution, and had taken them into account only as ‘corroborative’ or ‘complementary’ evidence.

The Government further argued that in many different parts of the world, criminal organisations pursued illegal activities under the cloak of legal structures which exploited the advantages offered by democracy and human rights. In that regard, the Government referred to the Court's judgment in Ayoub and Others (cited above) in support of their contention that some such organisations had also been identified in the Court's case-law. They submitted that there was no reason for the Court to depart from this line of case-law in view of the activities performed by the FETÖ/PDY and of its purpose, namely to abolish the constitutional order.

The right to freedom of association laid down in Article 11 incorporates the right to form an association. The ability to establish a legal entity in order to act collectively in a field of mutual interest is one of the most important aspects of freedom of association, without which that right would be deprived of any meaning (see Gorzelik and Others v. Poland [GC], no. 44158/98, § 88, ECHR 2004-I, and Sidiropoulos and Others v. Greece, 10 July 1998, § 40, Reports of Judgments and Decisions 1998-IV).

Indeed, the state of democracy in the country concerned can be gauged by the way in which this freedom is secured under national legislation and in which the authorities apply it in practice (see Gorzelik and Others, cited above, § 88). In its case-law, the Court has on numerous occasions affirmed the direct relationship between democracy, pluralism and the freedom of association and has established the principle that only convincing and compelling reasons can justify restrictions on that freedom. All such restrictions are subject to a rigorous supervision by the Court (ibid.).

The Court notes that in cases where there are no objective grounds capable of establishing the constituent elements of the offence of being a member of an armed terrorist organisation, such as in the instant case, the use by domestic courts of statements or acts that were manifestly non-violent — and that should in principle be protected by the Convention — in determining criminal liability may entail an interference with the rights concerned. The corroborative or complementary nature of the use made of these statements or acts in the criminal proceedings does not detract from that conclusion. In the present case, the judicial authorities' reliance in the bill of indictment and in the judgments on the applicant's membership of Aktif Eğitim-Sen and the Kayseri Voluntary Educators Association, even if only in an ancillary manner, was sufficient to constitute an interference with his rights under Article 11 of the Convention.

According to the Court's settled case-law the expressions ‘prescribed by law’ and ‘in accordance with the law’ in Articles 8 to 11 of the Convention not only require that the impugned measure should have some basis in domestic law, but that it should also be compatible with the rule of law, which, as indicated above, is inherent in all its Articles (see paragraph 350 above; see also Maestri v. Italy [GC], no. 39748/98, § 30, ECHR 2004-I). For the general principles with regard to the question whether an interference with the rights protected by those Articles was prescribed by law, the Court refers to its judgment in Selahattin Demirtaş (cited above, §§ 249-54).

In the present case, the Government argued that the purported interference had been prescribed by law, namely Article 314 § 2 of the Criminal Code as interpreted by the Court of Cassation. While the applicant did not contest that the interference had a basis in domestic law, he contended that the interpretation and application of the relevant provision on the present facts had fallen short of the requirement of lawfulness under Article 11 § 2 of the Convention. What is at stake in the present case is, therefore, the ‘quality’ of the law in question, in particular, whether it was foreseeable as to its effects (see, for instance, Kudrevičius and Others v. Lithuania [GC], no. 37553/05, § 108, ECHR 2015) and complied with the rule of law criterion under the second paragraph of Article 11 of the Convention.

It is common ground that the trade union and the association in question were established and were operating lawfully prior to their dissolution by Legislative Decree no. 667 after the attempted coup d'état on the ground that they posed a national security threat on account of their affiliation with the FETÖ/PDY. The Court considers that acts which appear on their face to come within the scope of Article 11 of the Convention and which do not incite violence or otherwise reject the foundations of a democratic society should benefit from a presumption of legality (compare, for a similar assessment made in the context of Article 5 of the Convention, Taner Kılıç, cited above, § 105). That being said, it is open to the domestic authorities to rebut this presumption in a given case. It should thus be ascertained whether the domestic authorities did so in the present case.

In that regard, the Court notes that there is no explanation in the trial court's judgment in respect of the nature of the actions of the trade union and the association in question which brought about their dissolution by Legislative Decree no. 667. The trial court's assessment on that point was limited to observing that they had been shut down pursuant to the said Legislative Decree on account of their affiliation with the FETÖ/PDY (see, for a similar finding, Adana TAYAD v. Turkey, no. 59835/10, §§ 33–34, 21 July 2020). Nor did the trial court's judgment contain any explanation as to whether the applicant had undertaken any acts within those structures, and, if so, what the nature of such acts was (see, for a similar situation in the context of a detention order under Article 5 of the Convention, Atilla Taş v. Turkey, no. 72/17, § 129, 19 January 2021). Moreover, the Ankara Regional Court of Appeal upheld the trial court's judgment, including as regards the evidence relied on, without shedding further light on these matters. Lastly, in their submissions before the Court, the Government did not submit any other domestic court judgment which offered further explanation in respect of these matters, but simply submitted that the trade union and the association in question had acted in accordance with the objectives of the FETÖ/PDY.

Accordingly, it appears that at no point during the criminal proceedings against the applicant did the domestic courts assess whether he had, in the context of his membership of Aktif Eğitim-Sen and Kayseri Voluntary Educators Association, engaged in any action which could be interpreted as inciting violence or otherwise rejecting the foundations of a democratic society. In that regard, it should further be noted that the Government did not put forward any specific evidence to rebut the presumption of legality (described above) in respect of the applicant's memberships of the trade union and association (see Atilla Taş, cited above, § 134). The Court considers that where no such elements are forthcoming, the mere fact of being a member of the trade union and the association in question, even when used only to corroborate the applicant's membership of an armed terrorist organisation, is not sufficient to rebut the presumption of legality.

At this juncture, the Court reiterates that in Selahattin Demirtaş (cited above), where that applicant's pre-trial detention in connection with serious offences punishable under Article 314 of the Criminal Code was based on his political statements and his involvement in a lawful organisation, it held that the range of acts that may have justified the applicant's detention was so broad that the content of that Article, coupled with its interpretation by the domestic courts, did not offer adequate protection against arbitrary interference by the national authorities (see also paragraph 201 above for the Venice Commission's opinion in that regard). The Court took the view that such a broad interpretation of a provision of criminal law could not be justified where it entailed equating the exercise of the right to freedom of expression with belonging to, forming or leading an armed terrorist organisation, in the absence of any concrete evidence of such a link (see Selahattin Demirtaş, cited above, §§ 277-80).

The question therefore arises whether the conclusions in the Selahattin Demirtaş judgment may be transposed to the instant case in the context of Article 11 of the Convention. In order to answer that question, careful consideration should be given to the factual circumstances of the two cases with a view to ascertaining whether they are such as to be regarded as sufficiently comparable to each other. The Court acknowledges that in Selahattin Demirtaş, the evidence underlying that applicant's detention and prosecution consisted solely of his speeches or acts that came within the exercise of his freedom of expression under Article 10 of the Convention. In the present case, the acts that enjoyed the protection of Article 11 were only relied on by the domestic courts as corroborating factors for the applicant's conviction. However, this is a difference in degree only, and the fact remains that the scope of Article 314 of the Criminal Code was extended unforeseeably to include membership of a trade union and an association — which were both operating lawfully at the material time — as indications of criminal conduct, without concrete elements which would fulfil the continuity, diversity and intensity criteria required in case-law interpreting that provision and demonstrating membership of an armed terrorist organisation. Accordingly, this factual difference does not seem sufficient to distinguish the present case from that of Selahattin Demirtaş.

Lastly, as regards the Government's argument that the present complaint should be rejected on the basis of Ayoub and Others (cited above), the Court considers that that case was materially different from the instant case, concerning the dissolution of three paramilitary-type far-right associations. The dissolution of the first of those associations had been based not on expressions of political views, but on, inter alia, an act of violence, namely the killing of an individual, whereas the second and third associations had been dissolved on the grounds that the objectives actually promoted and put into practice by their members, including on various occasions by violent means, had indisputably contained elements of incitement to hatred and racial discrimination aimed in particular at Muslim immigrants, Jews and homosexuals. Having regard to the considerable differences between the facts of the two cases, the Government's argument that the Court should adopt the same stance here as in Ayoub and Others (cited above) must be rejected.

In view of the foregoing considerations, the Court finds that the manner in which Article 314 § 2 of the Criminal Code was interpreted in the present case in relation to the applicant's membership of Aktif Eğitim-Sen and Kayseri Voluntary Educators Association extended the scope of that provision in an unforeseeable manner, did not afford the requisite minimum protection against arbitrary interference and cannot therefore be regarded as being ‘prescribed by law’ as required by Article 11 § 2 of the Convention.

In view of the above finding, it is unnecessary to examine whether the interference pursued one or more of the legitimate aims listed in paragraph 2 of Article 11 and was ‘necessary in a democratic society’.

In assessing the applicant's complaints under Article 6 from the standpoint of Article 15 of the Convention, the Court has already stressed that the need to ensure compliance with the principle of rule of law is indispensable at all times and that no derogation from it would be possible even in situations of emergency (see paragraph 350 above). Given that the rule of law is the principle underlying the Convention and all its provisions (see Grzėda, cited above, § 341), these considerations also hold true in respect of Article 11. Accordingly, when determining whether a derogating measure that encroaches upon the right to freedom of assembly and association was fully justified by the special circumstances of the emergency and was strictly required by the exigencies of the situation, the Court must also examine whether safeguards against arbitrary interferences by public authorities with the rights guaranteed by the Convention were provided and whether the measure undermined the rule of law.

The Government's request that the complaint under Article 11 be examined with due regard to the derogation notified on 21 July 2016 was based on the argument that the trade union and the association in question had been shut down by Legislative Decree no. 667 in the context of the measures taken during the state of emergency. The Court notes, however, that the breach of Article 11 at issue in the present case does not result from the shutting down of the relevant trade union and association, but from the fact that the applicant's membership of that trade union and association was used as corroborating evidence in securing his conviction for membership of an armed terrorist organisation. Be that as it may, the Government did not advance any explanations as to whether the specific use made by the domestic courts of the applicant's membership of the trade union and association in question had been strictly required by the exigencies of the situation giving rise to the state of emergency in Türkiye. Nor did they point to any domestic judgments where such assessment had been undertaken, in the context of the applicant's case or elsewhere.

The finding that the reliance placed on those acts breached the requirement of lawfulness on account of its unforeseeability meant that the domestic courts overly extended the scope of Article 314 § 2 of the Criminal Code, thereby depriving the applicant of the minimum protection against arbitrary interference, which protection is fundamental to safeguarding the rule of law (see paragraph 350 above, as relevant).

In view of the above, the Court holds that the Government have failed to demonstrate that the interference with the applicant's rights protected under Article 11 of the Convention could be regarded as being strictly required by the exigencies of the situation under Article 15.

In view of the foregoing considerations, the Court holds that there has been a violation of Article 11 of the Convention on the facts of the present case.

The findings of violation made in the present case, particularly those under Articles 7 and 6 of the Convention, entail an obligation on the respondent State to take appropriate measures to remedy these infringements of the applicant's rights.

As acknowledged in its case-law, there is a wide range of remedies in Europe enabling individuals to apply, following a finding by the Court of a violation of the Convention, for the reopening of a criminal case which has been concluded by a final judgment; however, there is no uniform approach among the Contracting States as regards the right to apply for reopening (see Moreira Ferreira, cited above, § 53).

Under Turkish law, domestic legislation explicitly provides for such a right under Article 311 § 1 (f) of the CCP, which stipulates, as relevant, that the reopening may be requested within one year following a final judgment of the Court finding a violation of the Convention or Protocols thereto. The Court has therefore often made reference to the possibility of reopening criminal proceedings in cases against Türkiye where an individual was found to have been convicted following proceedings that had entailed breaches of the requirements of Articles 6 or 7 of the Convention (see, for instance, Balta and Demir v. Turkey, no. 48628/12, § 70, 23 June 2015; Fikret Karahan v. Turkey, no. 53848/07, § 64, 16 March 2021; Faysal Pamuk v. Turkey, no. 430/13, § 79, 18 January 2022; and Sinan Çetinkaya and Ağyar Çetinkaya, cited above, § 49).

In the light of the principles set out above, and without prejudice to any general measures that may be required to prevent or redress other similar violations (see paragraph 418 below), the reopening of the criminal proceedings, if requested, would be the most appropriate way of putting an end to the violations found in the present case and of affording redress to the applicant. As indicated in the case of Sejdovic v. Italy ([GC], no. 56581/00, § 127, ECHR 2006-II), it is not for the Court to indicate how any new trial is to proceed and what form it is to take, the choice of means to discharge their legal obligations remaining at the discretion of the Government, provided that such means are compatible with the conclusions and spirit of the Court's judgment.

The Court observes that in the present case, the violations under Articles 7 and 6 of the Convention resulted notably from the domestic courts' characterisation of the use of ByLock. Under this approach, anyone whose use of that application was or is established by the domestic courts could, in principle, be convicted on that sole basis of membership of an armed terrorist organisation pursuant to Article 314 § 2 of the Criminal Code.

The Court therefore considers that the situation that led to a finding of violations of Articles 7 and 6 of the Convention in the present case was not prompted by an isolated incident or attributable to the particular turn of events, but may be regarded as having stemmed from a systemic problem. This problem has affected — and remains capable of affecting — a great number of persons (see, mutatis mutandis, Broniowski v. Poland [GC], no. 31443/96, § 189, ECHR 2004-V). This is evidenced by the fact that there are currently over 8,000 applications in the Court's docket involving similar complaints raised under Articles 7 and/or 6 of the Convention relating to convictions that were based on the use of ByLock as in the present case.

Following the relinquishment of jurisdiction in the present case to the Grand Chamber, the Government were requested to indicate the approximate number of criminal cases still pending before the domestic courts, including the Constitutional Court, involving charges under Article 314 § 2 of the Criminal Code on the basis of, in particular, the use of the ByLock messaging application as in the present case. The Government replied that the official statistics pertaining to the criminal cases pending before domestic courts did not include information that would enable them to respond to the Court's specific query. However, having regard to the number of ByLock users identified by the authorities, which was around one hundred thousand (see, for instance, paragraph 119 above), the Court notes that many more applications with similar complaints under Articles 7 and/or 6 of the Convention may potentially be lodged with it.

It is clear from the Court's case-law that where a violation originates in a systemic problem affecting a large number of people, general measures at national level will be called for in the execution of such a judgment (see, for instance, Broniowski, cited above, §§ 188-94, and Văleanu and Others v. Romania, nos. 59012/17 and 27 others, §§ 269-73, 8 November 2022). Although commonly resorted to in the framework of a pilot-judgment procedure as codified under Rule 61 of the Rules of Court, the Court has also indicated general measures in cases where that procedure was not applied (see, among many examples, Lukenda v. Slovenia, no. 23032/02, § 98, ECHR 2005-X; Hasan and Eylem Zengin v. Turkey, no. 1448/04, § 84, 9 October 2007; Manole and Others v. Moldova, no. 13936/02, § 117, ECHR 2009 (extracts); Grudić v. Serbia, no. 31925/08, § 99, 17 April 2012; Zorica Jovanović v. Serbia, no. 21794/08, §§ 92 and 93, ECHR 2013; Abdullah Yaşa and Others v. Turkey, no. 44827/08, § 61, 16 July 2013; Shishanov v. the Republic of Moldova, no. 11353/06, §§ 123-39, 15 September 2015; and Tunikova and Others v. Russia, nos. 55974/16 and 3 others, §§ 149-59, 14 December 2021). Whether made within the framework of a pilot judgment or otherwise, the aim with such indications is to assist the Contracting States in fulfilling their role in the Convention system by resolving systemic problems at national level.

The Court points in this regard to the States' general obligation to resolve the problems underlying any violations of the Convention, as indicated in Recommendation Rec(2004)6 of the Committee of Ministers (see Burmych and Others v. Ukraine (striking out) [GC], nos. 46852/13 et al., § 110, 12 October 2017). It further notes the Contracting States' recommitment to resolving the systemic and structural human rights problems identified by the Court and ensuring the full, effective and prompt execution of its final judgments, taking into account their binding nature, as expressed unequivocally during the recent Summit of Heads of State and Government held in Reykjavík (see Appendix IV to the Reykjavík Declaration cited as relevant at paragraph 204 above). The Court's concern is to facilitate the rapid and effective correction of a defect identified in the national system of human-rights protection and, as indicated in paragraph 408 above, its judgments serve not only to decide those cases brought before it. It therefore follows that once such a defect has been identified, the national authorities have the task, subject to supervision by the Committee of Ministers, of taking — retrospectively if need be — the necessary measures of redress in accordance with the principle of subsidiarity, which underpins the Convention system, so that the Court does not have to reiterate its finding of a violation in a series of comparable cases (see, Broniowski, cited above, § 193, and Scordino v. Italy (no. 1) [GC], no. 36813/97, § 236, ECHR 2006 V). The Court refers in this regard to its pertinent findings in the decision of E.G. v. Poland and 175 other Bug River applications ((dec.), no. 50425/99, § 27, ECHR 2008 (extracts)), as relevant:

The Court is therefore of the opinion that in order to avoid it having to establish similar violations in numerous cases in the future, the defects identified in the present judgment need, to the extent relevant and possible, to be addressed by the Turkish authorities on a larger scale — that is, beyond the specific case of the present applicant. It accordingly falls to the competent authorities, in accordance with the respondent State's obligations under Article 46 of the Convention, to draw the necessary conclusions from the present judgment, particularly in respect of, but not limited to, the cases currently pending before the domestic courts, and to take any other general measures as appropriate in order to resolve the problem identified above that has led to the findings of violation here (see paragraph 414 above; see also, mutatis mutandis, Guðmundur Andri Ástráðsson v. Iceland [GC], no. 26374/18, § 314, 1 December 2020). More specifically, the domestic courts are required to take due account of the relevant Convention standards as interpreted and applied in the present judgment. The Court underlines in this respect that Article 46 of the Convention has the force of a constitutional rule in Türkiye in accordance with Article 90 § 5 of the Turkish Constitution, according to which international agreements duly put into effect have the force of law and no appeal lies to the Constitutional Court to challenge their constitutionality (see paragraph 141 above).