Participation of third parties in proceedings before the Court of Justice of the European Union

Proceedings for a preliminary ruling

The Statute of the CJEU does not provide for the participation of third parties (other than those expressly mentioned in Article 23) in preliminary ruling proceedings and, consequently, for the submission of an amicus curiae by such persons. However, this does not mean that the participation of a third party in such proceedings is impossible. 

In accordance with Article 23 of the Statute of the CJEU, a third party may submit its written observations to the CJEU in preliminary ruling proceedings where it has been admitted to participate in the main proceedings (i.e., in the proceedings before the national court, which has referred a question to the CJEU for a preliminary ruling on the basis of Article 267 of the Treaty on the Functioning of the European Union (“TFEU”)).

The CJEU has indicated that:

“By the term 'parties', that article refers solely to the parties to the action pending before the national court (Case 62/72, Bollmann v Hauptzollamt Hamburg-Waltershof [1973] ECR 269, paragraph 4). (...) Consequently, a person who has not sought or been granted leave to intervene before the national court is not entitled to submit observations to this Court under that provision.” (Case C-181/95, paragraph 6)

The same position has been adopted by the CJEU in other cases such as C-403/08 and C-429/08. The third party should therefore become a party to the dispute or an intervener at the national level in order to be able to participate in the preliminary proceedings before the CJEU.

Thus, if a third party (e.g. a business organisation, professional association or NGO) wishes to intervene in the proceedings before the CJEU, it is necessary to consider the possibilities of participating in the case before the national court.

In most jurisdictions, it is permissible for a third party to intervene on the side of one of the litigants. An intervener has the same rights and obligations in legal proceedings as the party to which it has joined. However, the intervener must meet specific standing requirements. In particular, it must be able to demonstrate its own legitimate interest in having a particular judgment. Some jurisdictions such as Poland also allow specific third parties such as NGOs, business organisations, consumer organisations or certain public authorities to intervene as a party in cases that concern their area of activity or impact the interests of their members.

A more liberal approach was taken by the CJEU in Case C-266/16, in which the CJEU allowed the Moroccan Confederation of Agriculture and Rural Development to participate in the preliminary ruling procedure before the CJEU, even though the Confederation was not a party to the proceedings before the national court. The national court had only permitted the Confederation to join “as an interested party” in the proceedings pending before it. Similarly, in Case C-426/16, the Global Action in the Interest of Animals (“GAIA”) was accepted as an intervening party by the CJEU because the national court in Belgium had admitted this organisation to participate in the proceedings before the national court due to a “collective moral interest” in the protection of animal welfare.

It is therefore possible, in certain circumstances, for an entity to seek admission to the preliminary ruling procedure as an interested party, even if it is not acting as a party before the national court. However, eligibility for admission is subject to the prior acceptance of the interested party status by the national court.

In practical terms, it is most advantageous for a third party to intervene in the proceedings before the national court at the stage before the national court refers questions for a preliminary ruling to the CJEU. In that case, the third party may participate in the entire proceedings before the CJEU and provide its written observations.

However, it is also possible to intervene in the main proceedings after the national court has referred questions for a preliminary ruling to the CJEU. In such a case, the third party must accept the state of the case as it stands at the time that the CJEU is informed of its accession (Article 97 of the Rules of Procedure of the CJEU). If the third party intervenes in the proceedings after the expiry of the time-limit for the submission of written observations, and a hearing has been set in the case, the third party will not be entitled to submit written observations, but may still participate in the hearing.

Direct actions and appeals against the judgments of the General Court

The possibilities for third parties to intervene in proceedings initiated by direct action or in appeal proceedings against the judgments of the General Court are broader than in preliminary ruling proceedings.

Article 40 of the Statute of the CJEU provides that the right to intervene is available to any person if that person can justify an interest in the outcome of a case submitted to the CJEU. However, such a person may not intervene in cases between:

1. member states;
2. the institutions of the Union; or
3. member states and the institutions of the Union (Article 40(2) of the Statute of the CJEU).

According to the well-established position of the CJEU, an “interest in the outcome of the case” must be understood as a direct and present interest in the outcome of the claims made in the case and not as an interest in relation to the pleas or arguments raised. As a general rule, an interest in the outcome of a case can only be regarded as sufficiently direct if that outcome is capable of altering the legal position of the person seeking leave to intervene (per the order of the President of the CJEU dated 10 March 2023, C‑611/22 P, paragraph 7).

However, it is settled case-law of the CJEU that a representative professional association, whose objective is to protect the interests of its members, may be granted leave to intervene where the case raises questions of principle, which are liable to affect those interests of the association’s members (per the order of the CJEU dated 27 April 2023, C-337/22 P, paragraph 9).

Intervention is objectively limited in that the intervener may only support, in whole or in part, the claims of one of the parties. It may not put forward its own claims (per the judgment of the CJEU dated 4 February 2020, C-515/17 P).