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
Accession of the United Kingdom to the European Communities Accession of the United Kingdom to the European Communities The Accession of the United Kingdom to the European Communities (EC) – the collective term for the European Coal and Steel Community (ECSC), the European Economic Community (EEC) and the European Atomic Energy Community (EAEC) – took effect on 1 January 1973. This followed ratification of the Accession treaty which was signed in Brussels on 22 January 1972 by the Conservative prime minister Edward Heath, who had pursued the UK's application to the EEC since the late 1950s. Denmark and Ireland also joined as part of the same expansion but Norway,