3.3.4.4 Ex tunc effect versus legal certainty

119. In Bressol the Court of Justice recalled what it had already held in earlier cases, such as Blaizot and Bosman:

The trade unions argued that at the time of their collective actions the state of the law was unclear and that as a consequence the eventual damages payable should be mitigated.2 The Arbetsdomstolen, however, states that although the collective actions were in line with national regulations (in particular the Lex Britannia), they were anyhow in conflict with Article 56 TFEU. Since the Court of Justice has not limited the effect of its Laval ruling, the judgment has effect not only in future cases, but also in cases dating from before the judgment. Consequently, the ruling applies to violations prior to the judgment, like the collective actions at issue.3

120. In the literature on Laval, the term ‘retroactive effect’ is frequently spotted.4 It is, however, questionable whether the concept of retroactive effect indeed applies to this case. After all, the Court of Justice’s interpretation of Article 56 TFEU does not constitute a new rule:5 Article 56 TFEU should be interpreted this way since it entered into force. This approach is closer to the concept of ex tunc effect rather than that of retroactive effect. On the other hand, it should be noted that the term ‘retroactive effect’ is often also used to indicate that certain decisions date back in time.6 As a rule, the rulings of the Court of Justice date back in time and therefore the interpretation it gives to rules of Union law does as well. Below, the term ex tunc effect is used to indicate the backdating effect of rulings of the Court of Justice on the interpretation of Union law.

121. Building on the Court of Justice’s reasoning for the ex tunc effect in cases of Member State liability7, the Arbetsdomstolen emphasises that if judgments of the Court of Justice would not have ex tunc effect, the right to award damages according to the EU’s legal system would be jeopardised. In relation to the case at hand, the Arbetsdomstolen considers that even if the state of the law was not established, the trade unions had sufficient reason to doubt the lawfulness of their collective actions, all the more since Laval, in its objections against the actions, delivered a well-founded reasoning as to why the actions of the trade unions were in conflict with Union law.8 It is settled case law of the Arbetsdomstolen “that high demands must be placed on the labour organisations when it comes to investigation with exactitude and care, whether a planned collective action is not prevented by an eventual arising duty to maintain the industrial peace. The same view ought to be applied, according to the view of the Arbetsdomstolen, when it comes to those impediments that [EU] law can potentially lay down”.9 Noteworthy is that the Arbetsdomstolen holds that its interlocutory judgment – in which the court determined that it was improbable that the collective actions taken were unlawful – lacks any significance in the context of the main proceedings.10