European integration for greater transparency and trust among themselves. This transfer of national powers to a "Community" to be exercised by its Commission was paralleled under the 1957 Treaty of Rome establishing the European Atomic Energy Community (or Euratom) and the European Economic Community (EEC) in Brussels. In 1967, the Merger Treaty (or Brussels Treaty) combine the institutions of the ECSC and Euratom into that of the EEC. They already shared a Parliamentary Assembly and Courts. Collectively they were known as the European Communities. In 1987, the Single European Act (SEA) was the first major revision of the Treaty of Rome that
European Economic Community the ECSC and Euratom were merged with that of the EEC, creating a single institutional structure governing the three separate Communities. From here on, the term "European Communities" were used for the institutions (for example, from "Commission of the European Economic Community" to the "Commission of the European Communities"). The Council of the European Communities was a body holding legislative and executive powers and was thus the main decision making body of the Community. Its Presidency rotated between the member states every six months and it is related to the European Council, which was an informal gathering of national leaders