Single European Act

The Single European Act (SEA) was the first major revision of the 1957 Treaty of Rome establishing the European Economic Community. It was signed in two stages in Luxembourg and The Hague in February 1986 and entered into force on 1 July 1987, after Ireland completed ratification following the Crotty v. An Taoiseach Supreme Court ruling that required a constitutional referendum.

The SEA's central ambition was to complete the internal market — an "area without internal frontiers in which the free movement of goods, persons, services and capital is ensured" — by 31 December 1992. This timetable operationalised the program set out in the European Commission's 1985 White Paper on Completing the Internal Market, prepared under Commissioner Lord Cockfield and Commission President Jacques Delors.

Key institutional changes included:

• Qualified majority voting (QMV) extended in the Council of Ministers to most single-market legislation, breaking the de facto unanimity practice that had prevailed since the 1966 Luxembourg Compromise.
• A formal cooperation procedure giving the European Parliament a stronger second reading on many measures.
• An assent procedure for accession and association agreements.
• Treaty recognition of the European Council of heads of state and government, which had operated informally since 1974.
• New competences in environmental policy, research and technological development, economic and social cohesion, and health and safety at work.
• Codification of European Political Cooperation (EPC), the precursor to the Common Foreign and Security Policy.

Politically, the SEA broke the "Eurosclerosis" of the late 1970s and early 1980s and laid the groundwork for the 1992 Maastricht Treaty, which created the European Union and the path to the euro. It is generally regarded as the most consequential European integration step between the founding Rome Treaties and Maastricht.