The Court of Justice of the European Union is the judicial institution of the European Union and of the European Atomic Energy Community (Euratom). It is made up of three courts: the Court of Justice, the General Court and the Civil Service Tribunal. Their primary task is to examine the legality of European Union measures and ensure the uniform interpretation and application of European Union law.

Through its case-law, the Court of Justice has identified an obligation on administrations and national courts to apply EU law in full within their sphere of competence and to protect the rights conferred on citizens by that law (direct application of EU law), and to disapply any conflicting national provision, whether prior or subsequent to the EU provision (primacy of European Union law over national law).

The Court of Justice also works in conjunction with the national courts, which are the ordinary courts applying EU law. Any national court or tribunal which is called upon to decide a dispute involving EU law may, and sometimes must, submit questions to the Court of Justice for a preliminary ruling. The Court must then give its interpretation or review the legality of a rule of EU law.

The development of its case-law illustrates the Court's contribution to creating a legal environment for citizens by protecting the rights which European Union legislation confers on them in various areas of their daily life.