where you can also find a brief history and a glossary of terms used in the EU.
The European Union, which succeeded the European Community, was established by the EU Treaties.
The parties to the treaties are the Member States of the EU.
Under the treaties the Member States confer competences on the EU – such as the power to adopt legislation. The EU can only act within the limits of its competences.
The EU has a number of institutions, such as the European Council, the Council of Ministers, the European Commission and the European Parliament. Acting together or separately, these institutions pass laws (such as regulations, directives or decisions), which may take effect automatically in the UK’s legal systems or require the UK to pass national legislation to give effect to the EU laws.
The UK may also be affected by the treaties themselves, which may restrict what the UK can do, for example, restricting the UK’s power to limit imports from other Member States.
The Court of Justice of the European Union interprets the treaties and the laws which the EU passes and decides if Member States have abided by them.
There are two key EU treaties, which have been amended several times.
They are the Treaty on the European Union (‘TEU’, originally the Maastricht Treaty), and the Treaty on the Functioning of the European Union (‘TFEU’, originally called the Treaty of Rome). The treaties are effective in the UK by virtue of the European Communities Act 1972, as amended.
The full text of the Maastricht Treaty can be found on the EU web-site at
The European Economic Community was established in 1957 by the Treaty of Rome, and became the European Community (EC) in 1967. The Treaty of Rome gave the Community a number of tasks including establishing a common market and progressively approximating the economic policies of the Member States. The United Kingdom joined the Community in 1973, and confirmed that decision in a UK-wide referendum in 1975.
In 1986, the Single European Act made further provision for the establishment of the common market, now referred to as the ‘internal market’, and defined as an area without internal frontiers, in which the free movement of goods, persons, services and capital is ensured. The Single Market Act also added a number of new policy areas to the Community’s competence, including, for example, a specific environmental competence. The Maastricht Treaty followed in 1993. This treaty established the European Union, which had a three pillar structure, with the European Community being the first pillar, the common foreign and security policy the second pillar and justice and home affairs (covering immigration and asylum, civil judicial cooperation and police and judicial cooperation in criminal matters) the third pillar. Further changes were made by the Treaty of Amsterdam (1997) and the Treaty of Nice (2000), including to the competences of the Union.
The EU entered a period of expansion, reaching 28 Member States by 2013. This prompted calls for a new Treaty. After long discussion, the Lisbon treaty was signed in 2007. This treaty renamed and amended the original treaties, collapsed the three pillar system into a single European Union, and incorporated the Charter of Fundamental Rights into the EU Treaties.