The Member States 7 February 1992, Consolidated version of the Treaty on European Union#TITLE I - COMMON PROVISIONS#Article 4

Article 4 1. In accordance with Article 5, competences not conferred upon the Union in the Treaties remain with the Member States. 2. The Union shall respect the equality of Member States before the Treaties as well as their national identities, inherent in their fundamental structures, political and constitutional, inclusive of regional and local self-government.