The EC Merger Treaty ( formally the Treaty establishing a Single Council and a Single Commission of the European Communities, rarely Treaty of Brussels ) led to the establishment of a Joint Commission and a Single Council of the then three European Communities (European Economic Community, European Coal and steel and the European atomic Energy Community ). The merger agreement was signed in Brussels on 8 April 1965 and entered into force on 1 July 1967.
According to the Convention on certain institutions for the European Communities of 25 March 1957, which was part of the Treaty of Rome already loud Final Act, the three communities had already before 1967 a Joint Parliamentary Assembly ( now Parliament), a common Court of Justice and a common Economic and social Committee divided. However, EEC, ECSC and Euratom each had their own commission ( which was described in the case of the ECSC High Authority as ) and their own Ministers. With the merger agreement for one of the Special Council of Ministers ( ECSC) and the two Councils of Ministers (EEC, Euratom) and on the other the High Authority ( ECSC) and the two Commissions (EEC, Euratom ) were each merged. In this way, the merger of the institutions was completed.
Since the establishment of the European Union by the Treaty of Maastricht in 1992, the EC institutions were also used for the policies of the EU, which emerged directly out of the EU Treaty. In 1997, the merger agreement under Article 9 paragraph 1 of the Treaty of Amsterdam was canceled. Its essential elements, however, were taken over (EC Treaty, the ECSC Treaty and the Euratom Treaty ) in the consolidated treaty and therefore remained valid. After the expiry of the ECSC Treaty (2002) and the rising of the EC in the EU by the Treaty of Lisbon in 2009 exists today of the original three communities, only the Euratom who shares her organs with the European Union.