The Member States 25 March 1957, Consolidated version of the Treaty on the Functioning of the European Union#PART ONE - PRINCIPLES#TITLE I - CATEGORIES AND AREAS OF UNION COMPETENCE#Article 4

Article 3 1. The Union shall have exclusive competence in the following areas: (a) customs union; (b) the establishing of the competition rules necessary for the functioning of the internal market; (c) monetary policy for the Member States whose currency is the euro; (d) the conservation of marine biological resources under the common fisheries policy; (e) common commercial policy. 2.