Treaties of the European Union the Functioning of the European Union (originally signed in Rome in 1957 as the Treaty establishing the European Economic Community, aka The Treaty of Rome), lay out how the EU operates, and there are a number of satellite treaties which are interconnected with them. The treaties have been repeatedly amended by other treaties over the 65 years since they were first signed. The consolidated version of the two core treaties is regularly published by the European Commission. The two principal treaties on which the EU is based are the Treaty on European Union (TEU; Maastricht Treaty, effective since 1993) and
European Coal and Steel Community their fields rapidly expanded and the EEC became the most important tool for political unification, overshadowing the ECSC. Despite being separate legal entities, the ECSC, EEC and Euratom initially shared the Common Assembly and the European Court of Justice, although the Councils and the High Authority/Commissions remained separate. To avoid duplication, the Merger Treaty merged these separate bodies of the ECSC and Euratom with the EEC. The EEC later became one of the three pillars of the present day European Union. The Treaty of Paris was frequently amended as the EC and EU evolved and expanded. With the treaty due