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
Treaty of Rome full name of which was the Treaty establishing the European Economic Community has been amended by successive treaties significantly changing its content. The 1992 Treaty of Maastricht established the European Union, the EEC becoming one of its three pillars, the European Community. Hence, the treaty was renamed the Treaty establishing the European Community (TEC). When the Treaty of Lisbon came into force in 2009, the pillar system was abandoned; hence, the EC ceased to exist as a legal entity separate from the EU. This led to the treaty being amended and renamed as the Treaty on the Functioning of the