Treaty of Maastricht

The Treaty on European Union, signed in Maastricht, the Netherlands, on 7 February 1992 and entering into force on 1 November 1993, transformed the European Communities into the European Union (EU). It was negotiated by the then-twelve member states of the European Communities and is widely treated as the founding document of the EU in its modern form.

Maastricht organised the new Union around a three-pillar structure:

• The European Communities pillar, covering the single market, economic and monetary policy, and most supranational competences.
• The Common Foreign and Security Policy (CFSP), an intergovernmental pillar for coordinated external action.
• Justice and Home Affairs (JHA), covering cooperation on policing, asylum, immigration, and judicial matters.

Among its most consequential provisions, the treaty:

• Established European Union citizenship for nationals of member states, including rights to move, reside, and vote in local and European Parliament elections in any member state.
• Set out a timetable and convergence criteria (on inflation, deficits, debt, exchange rates, and interest rates) for Economic and Monetary Union (EMU) and the creation of a single currency, later named the euro.
• Created the European Central Bank and the European System of Central Banks (which became operational later in the decade).
• Introduced the co-decision procedure, expanding the European Parliament's legislative role alongside the Council.
• Codified the principle of subsidiarity, requiring action at EU level only where objectives cannot be sufficiently achieved by member states alone.

The United Kingdom secured opt-outs from the single currency and the Social Chapter, and Denmark obtained four opt-outs (including on the euro and defence) after Danish voters initially rejected the treaty in a June 1992 referendum and approved a revised package in May 1993. France ratified it by referendum in September 1992 by a narrow "petit oui."

Maastricht's pillar structure was later collapsed and amended by the treaties of Amsterdam (1997), Nice (2001), and Lisbon (2007).