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Founding agreements

The European Union is based on the rule of law. This means that every action taken by the EU is founded on treaties that have been approved voluntarily and democratically by all EU member countries. For example, if a policy area is not cited in a treaty, the Commission cannot propose a law in that area.

A treaty is a binding agreement between EU member countries. It sets out EU objectives, rules for EU institutions, how decisions are made and the relationship between the EU and its member countries.

Treaties are amended to make the EU more efficient and transparent, to prepare for new member countries and to introduce new areas of cooperation – such as the single currency.

Under the treaties, EU institutions can adopt legislation, which the member countries then implement. The complete texts of treaties, legislation, case law and legislative proposals can be viewed using the EUR-Lex database of EU law.

Sorted chronologically from latest to oldest, the main treaties are:

When new countries joined the EU, the founding treaties were amended:

  • 2013 (Croatia)
  • 2007 (Bulgaria, Romania)
  • 2004 (Czechia, Cyprus, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, Slovenia)
  • 1995 (Austria, Finland, Sweden)
  • 1986 (Spain, Portugal)
  • 1981 (Greece)
  • 1973 (Denmark, Ireland, United Kingdom).