The plea of illegality in European Union law – The missing piece in the puzzle of a ‘complete system of remedies’?, by Mariolina Eliantonio


In Les Verts – and a long-standing line of case law thereafter – the Court of Justice of the European Union (CJEU) affirmed that a ‘complete system of remedies’ exists in the European Union (EU) legal order, which allows the European courts to review all the actions of any EU institution. In the multi-level EU legal system, this supposedly ‘complete system of remedies’ is concretised in the possibility of challenging the EU (administrative) action either directly or indirectly. The direct system of judicial review comprises the action for annulment under Article 263 TFEU and the action for failure to act under Article 265 TFEU. Furthermore, there are two possibilities to indirectly challenge the EU (administrative) action, namely before a national court through a preliminary question of validity under Article 267 TFEU and before an EU court through the procedure known as the ‘plea of illegality’ provided for in Article 277 TFEU.

Through the plea of illegality, an applicant may plead the invalidity of an underlying piece of EU law when directly challenging an EU law measure, the basis of which lies in the allegedly invalid higher piece of EU law. As held by the CJEU in Albini, this form of review is not considered to be an independent action, and it can only be brought in the context of a direct action, most often an action for annulment under Article 263 TFEU. The importance of these two systems of indirect review has been stressed time and again by the CJEU in the context of allegations – brought forward by Advocate Generals (e.g. AG Jacobs in ECLI:EU:C:2002:197) and scholarship (A. Albors-Llorens) alike – that direct access to the EU courts is too restrictive because of the narrow standing conditions to be fulfilled in direct actions and, more particularly, because of the notion of ‘individual concern’ which private applicants typically need to demonstrate in actions for annulment.

Our chapter forthcoming in a book on indirect review of administrative action in a comparative perspective disproves the supposedly complete nature of remedies of the EU legal system, in particular, with respect to the ‘plea of illegality’ under Article 277 TFEU. After discussing the key features of the plea of illegality, we carry out an empirical analysis of the use of the plea of illegality in practice. This analysis, and the ensuing discussion, show that the plea of illegality has been only rarely used and has even more rarely led to the annulment of the measure indirectly challenged.

Direct review of administrative action before the EU Courts and the link between Articles 263 and 277 TFEU

The current version of Article 263 TFEU, in essence, foresees five possible scenarios of standing as illustrated in the Table below.

Type of actDirect concernIndividual concern
Act of individual application and the applicant is the addressee
Act of individual application and the applicant is not the addresseeXX
Act of general application which is not a ‘regulatory act’XX
Act of general application which is a ‘regulatory act’ but entails implementing measuresXX
Act of general application which is a ‘regulatory act’ and does not entail implementing measuresX

As is well known, whenever individual concern needs to be proven, direct access to EU courts is severely limited by the Plaumannbased interpretation of this concept by the CJEU.

This is even more the case for acts of general application. Indeed, if the contested act is an act of general application, is it not sufficient to prove, as for acts of individual application, that the applicant forms part of the abovementioned closed group of persons (Weber, ECLI:EU:T:1996:97). Furthermore, according to the court, the fact that the persons to which a measure is applicable are identifiable (Zuckerfabrik, ECLI:EU:C:1968:43), that the act only applies to a small number of individuals (Commission v Jégo-Quéré & Cie SA, ECLI:EU:C:2004:210), that the act affects certain market participants more harshly than their competitors (Alpenhain-Camembert-Werk, ECLI:EU:T:2004:209) or that the act affects an applicant’s competitive relationships (Società ‘Eridania’ Zuccherifici Nazionali, ECLI:EU:C:1969:66) is not sufficient to establish individual concern. There are only a handful of cases concerning acts of general application in which individual concern was held to be established, namely when an act of general application affected the specific rights of the applicant (Codorníu, ECLI:EU:C:1994:197)or when the applicant could show that, in adopting the measure of general application, the concerned EU institution was under a duty to take its specific circumstances into account (SA Piraiki-Patraiki, ECLI:EU:C:1985:18) or, finally, when the act, despite not being addressed to the applicant, mentioned the latter by name (SA Roquette Frères, ECLI:EU:C:1980:249).

The mechanism foreseen in Article 277 TFEU is theoretically construed to function as a ‘safety net’ to provide applicants with a means to ask the court to review the legality of these acts. In the words of the court (SpA Simmenthal v Commission, ECLI:EU:C:1979:53), the mechanism of the plea of illegality:

“gives expression to a general principle conferring upon any party to proceedings the right to challenge, for the purposes of obtaining the annulment of a decision of direct and individual concern to that party, the validity of previous acts of the institutions which form the legal basis of the decision which is being attacked, if that party was not entitled under [Article 263 TFEU] to bring a direct action challenging those acts by which it was thus affected without having been in a position to ask that they be declared void.”

The plea of illegality put to the test

To test whether the plea of illegality serves to challenge indirectly before the EU Courts what cannot be directly challenged, we sought to discover the frequency of cases based on this procedure and the rate of success of these cases.

We identified, in the period 2009–2021, a total of 24 cases in which the plea of illegality has been invoked by parties, or where the court mentioned that the procedure should have been invoked. 11.1The clue to solving this ‘mystery’ of the limited use of the plea of illegality during our reference period may be the scope and definition of the notion of ‘regulatory act not entailing implementing measures’ introduced by the Lisbon Treaty. The definition for the term ‘regulatory act’ was first established by the CJEU in October 2011 in Microban (ECLI:EU:T:2011:623), quickly complemented in 2013 with Inuit Tapiriit Kanatami (ECLI:EU:C:2013:625), and confirmed by the CJEU in 2015 in the appeal (ECLI:EU:C:2013:625) on that case. The result is that, at the moment, regulatory acts are ‘any acts of general application other than legislative acts.’

However, according to Article 263 Paragraph 4 TFEU, the direct review of regulatory acts should take place only when they do not entail implementing measures. The rationale here is clear: should a non-legislative act need implementation by a Member State, the system of judicial review reverts to the mechanism in place for legislative acts, where the national court is empowered to request a preliminary reference. If the Commission or any other body of the EU need to take any further action, the review of this non-legislative act will be possible through Article 277.

Given the increasingly complex regulatory capacity in which the EU and its bodies operate, this last situation is far from extraordinary. However, the court has chosen to take a broad approach to what constitutes an ‘implementing measure’. First set out in Telefónica (ECLI:EU:C:2013:852), and later refined in T and L Sugars (ECLI:EU:C:2015:284), the court interpreted the ‘implementing measure’ to mean any act undertaken by the Member State (or, by analogy, any EU body) to give effect to an EU act. This means that in Telefónica, the telecom provider would have been directly concerned by the finding of the Commission that the funds it received from the Spanish government constituted state aid. Nevertheless, the court concluded that, as an extra action had to be undertaken by the Member State for Telefónica to be affected by that finding, namely the retrieval of the state aid, the telecom provider could not rely on Article 263 TFEU against it. In T and L Sugars, the AG remarked on how this interpretation ran counter-intuitive to the quite similar interpretation of ‘direct concern’, noting how he believed ‘entailing implementing measures’ served a different purpose. Yet, the court went one step further and effectively judged how any intercession by a Member State, here the mere check whether a sugar producer met the criteria to participate in a scheme set up to combat a temporary sugar shortage, constituted an ‘implementing measure’ in the light of Paragraph 4 of Article 263 TFEU (T and L Sugars, ECLI:EU:C:2015:284).

The definition of ‘regulatory act’, combined with the overly broad interpretation of not ‘entail[ing] implementing measures’ seems to have led to a minimal use and even more minimal success rate of the procedure post-Lisbon. This conclusion can be drawn from the 24 cases in which Article 277 TFEU has been invoked before the CJEU. In almost every one of these 24 cases, the court makes a point of explaining, first, how the possibility to appeal against non-legislative acts of general application is open only to those acts that do not require further implementation. The existence of any implementing act would open up the route through a preliminary reference under Article 267 TFEU. Second, according to the court, the regulatory act opens the possibility for applicants to indirectly challenge a mother act, i.e., the legislative act from which the authority to delegate or implement is derived, where the regulatory act (by the Commission or an EU body) affects applicants directly. Despite these principled statements, most pleas based on Article 277 TFEU are, in fact, rejected, as the broad interpretation of the court, set out above, will always lead to the possibility of a national point of entry to the system of judicial review.

Conclusions: a ‘complete’ system of remedies?

The plea of illegality has been consistently heralded as one of the cornerstones of the allegedly complete ‘system of remedies’ that is so well known by those authors who have long critiqued the position of the court on the action for annulment. Our empirical investigation led us to vastly different findings: the plea of illegality has hardly ever been used in challenges before the EU courts and has almost invariably been used unsuccessfully. This result is most likely due to the CJEU’s overly restrictive interpretation of the notion of ‘regulatory act not entailing implementing measures’, the very notion the Treaty of Lisbon introduced to resolve the existing gaps in judicial protection. Combined with the fact that, to this day, the direct means to judicial review through Article 263 TFEU and indirect review through Article 267 TFEU are still heavily criticised as not offering significant relief to natural and legal persons in addressing possible errors in EU law- and decision-making, the plea of illegality is the missing piece of the jigsaw that, in hindsight, does not fit.

Posted by Professor Mariolina Eliantonio (Maastricht University)

Suggested citation: M. Eliantonio, ‘The plea of illegality in European Union law – The missing piece in the puzzle of a ‘complete system of remedies’?’ available at