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 Communities European Communities The European Communities (EC), sometimes referred to as the European Community, were three international organizations that were governed by the same set of institutions. These were the European Coal and Steel Community (ECSC), the European Atomic Energy Community (EAEC or Euratom), and the European Economic Community (EEC); the last of which was renamed the "European Community" ("EC") in 1993 by the Maastricht Treaty, which formed the European Union. When the Communities were incorporated into the European Union in 1993, they became its first pillar. The European Coal and Steel Community ceased to exist in 2002 when its founding