EU cooperation began in the 1950s as an economic union between six European countries, and today the European Union (EU) is a large regional organization made up of 27 European countries. EU legal structure has been based on an amalgam of treaties and agreements entered into between 1953 and 2007.

In 2007, the Treaty of Lisbon consolidated and amended these agreements and now serves as governing document for the EU. EU policy and governance, however, is explained as resting on three "pillars," listed below, each of which stems from formerly applicable treaties on the subject. The three pillars are:

• Economic - from the three communities of the European Coal and Steel Community (ECSC), the Economic Community (EC) and Euratom (the European Atomic Energy Community)
• Foreign Policy and Security - Common Foreign and Security Policy (CFSP)
• Justice and Home Affairs - Police and Judicial Co-operation in Criminal Matters (PJCC)