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 Economic Community Community", continuing to follow the supranational structure of the EEC. The EEC institutions became those of the EU, however the Court, Parliament and Commission had only limited input in the new pillars, as they worked on a more intergovernmental system than the European Communities. This was reflected in the names of the institutions, the Council was formally the "Council of the "European Union"" while the Commission was formally the "Commission of the "European Communities"". However, after the Treaty of Maastricht, Parliament gained a much bigger role. Maastricht brought in the codecision procedure, which gave it equal legislative power with the