Three pillars of the European Union

Between 1993 and 2009, the European Union (EU) legally comprised three pillars. This structure was introduced with the Treaty of Maastricht on 1 November 1993, and was eventually abandoned on 1 December 2009 upon the entry into force of the Treaty of Lisbon, when the EU obtained a consolidated legal personality.

Within each pillar, a different balance was struck between the supranational and intergovernmental principles.

Supranationalism was strongest in the first pillar. Its function generally corresponded at first to the three European Communities (European Coal and Steel Community (ECSC), European Economic Community (EEC) and Euratom) whose organisational structure had already been unified in 1965-67, through the Merger Treaty. Later, through the Treaty of Maastricht the word "Economic" was removed from the EEC, so it became simply the EC. Then with the Treaty of Amsterdam additional areas would be transferred from the third pillar to the first. In 2002, the ECSC (which had a lifetime of 50 years) ceased to exist because the treaty which established it, the Treaty of Paris, had expired.

In the CFSP and PJCCM pillars the powers of the European Parliament, the Commission and European Court of Justice with respect to the Council were significantly limited, without however being altogether eliminated. The balance struck in the first pillar was frequently referred to as the "community method", since it was that used by the European Community.

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