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
High Authority of the European Coal and Steel Community reached. Future executives, the Commissions of the EEC and Euratom, would eventually be based in Brussels. High Authority of the European Coal and Steel Community The High Authority was the executive branch of the former European Coal and Steel Community (ECSC). It was created in 1951 and disbanded in 1967 when it was merged into the European Commission. The High Authority was at the core of the idea of the ECSC. It was to be an independent, supranational executive checked by a Common Assembly. There were concerns about this power, leading to a Council (of governments) and Parliament (of MPs)