The Treaty of Maastricht which established the European Union, divided EU policies into three main areas, called pillars.

The three pillars

1. The first or 'Community' pillar concerns economic, social and environmental policies.
2. The second or 'Common Foreign and Security Policy' (CFSP) pillar concerns foreign policy and military matters.
3. The third or 'Police and Judicial Co-operation in Criminal Matters' (PJCC) pillar concerns co-operation in the fight against crime. This pillar was originally named 'Justice and Home Affairs'.

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

Supranationalism is 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 organizational structure had already been unified in the 1960s 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 ceased to exist because the treaty which established it, the Treaty of Paris, had expired.

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

Origin of the three pillars structure

The pillar structure had its historical origins in the negotiations leading up to the Maastricht treaty. It was desired to add powers to the Community in the areas of foreign policy, security and defence policy, asylum and immigration policy, criminal co-operation, and judicial co-operation.

However, some member-states opposed the addition of these powers to the Community on the grounds that they were too sensitive to national sovereignty for the community method to be used, and that these matters were better handled intergovernmentally. To the extent that at that time the Community dealt with these matters at all, they were being handled intergovernmentally, principally in European Political Cooperation (EPC).

As a result, these additional matters were not included in the European Community; but were tacked on externally to the European Community in the form of two additional 'pillars'. The first additional pillar (Common Foreign and Security Policy, CFSP) dealt with foreign policy, security and defence issues, while the second additional pillar (JHA, Justice and Home Affairs), dealt with the remainder.

Recent amendments in the treaty of Amsterdam and the treaty of Nice have made the additional pillars increasingly supranational. Most important among these has been the transfer of policy on asylum, migration and judicial co-operation in civil matters to the Community pillar, effected by the Amsterdam treaty. Thus the third pillar has been renamed Police and Judicial Co-operation in Criminal Matters, or PJCC. The term Justice and Home Affairs is still used to cover both the third pillar and the transferred areas.

Evolution of the structures of the European Union.

Abolition of the pillar structure

The drafted European Constitution, if ratified by all member states, is meant to simplify and unify the operations of the European Union. As such the European Community is to be fully absorbed into the European Union and the three pillars of the EU are to be merged into a single structure.