The European Union's political system has been constantly evolving over the past 50 years. The ground rules of the EU are set out in a series of treaties: the Treaty of Paris, which set up the European Coal and Steel Community (ECSC) in 1951 and the Treaties of Rome, which set up the European Economic Community (EEC) in 1957; and the subsequent revisions by the Single European Act (1986), and the Maastricht, Amsterdam and Nice treaties agreed in the 1990s. Under these treaties, the member states of the EU delegate some of their national sovereignty to the European institutions. There is an ongoing debate about how much national sovereignty should be surrendered to the European level.
