Since the establishment of the Court of Justice of the European Union in 1952, its mission has been to ensure that "the law is observed" "in the interpretation and application" of the Treaties.

As part of that mission, the Court of Justice of the European Union:

reviews the legality of the acts of the institutions of the European Union,

ensures that the Member States comply with obligations under the Treaties, and

interprets European Union law at the request of the national courts and tribunals.

The Court thus constitutes the judicial authority of the European Union and, in cooperation with the courts and tribunals of the Member States, it ensures the uniform application and interpretation of EU law.

The Court of Justice of the European Union, which has its seat in Luxembourg, consists of two courts: the Court of Justice and the General Court (created in 1988). The Civil Service Tribunal, established in 2004, ceased to operate on 1 September 2016 after its jurisdiction was transferred to the General Court in the context of the reform of the European Union’s judicial structure.

As each Member State has its own language and specific legal system, the Court of Justice of the European Union is a multilingual institution. Its language arrangements have no equivalent in any other court in the world, since each of the official languages of the European Union can be the language of a case. The Court is required to observe the principle of multilingualism in full, because of the need to communicate with the parties in the language of the proceedings and to ensure that its case-law is disseminated throughout the Member States.