The Treaty of Rome established in 1957 an economic bloc which set up an area of free trade in certain manufactured goods. It also established a highly protected agricultural system. It set up the 'European Economic Community' (EEC - now the EU) institutions: the European Commission, the Council of Ministers, the European Parliament and the European Court of Justice. They were given supranational powers (powers greater than national powers) over the states in certain areas. In other words, the laws (directives and regulations as they are called) issued by the EU to enforce the rules set out in the Treaties are legally binding on the member states and their systems. So side-by-side with industrial free trade and a protected agricultural system, institutions were set up to run this new bloc of member states and to enforce the Treaties.

What we call the European Union today is not a State. It is not even a legal or corporate entity in its own right, for it does not have legal personality. The name 'European Union' at present is the descriptive legal term for the totality of relations between its 27 Member States and their peoples. The European Union is more than just a confederation of countries, but it is not a federal state. It is, in fact, a new type of structure that does not fall into any traditional legal category. Its political system is historically unique and has been constantly evolving over more than 50 years. Citizenship of the European Union at present is stated to 'complement' national citizenship, in other words it's mostly notional.