The EU makes laws which must be respected by all member states. Since the aim behind the creation of new European laws is often to standardise laws between the different member states, it is inevitable that EU laws are passed which some member states do not like. Even if they do not like them, however, all member states have to obey EU laws. For member states of the EU, it is no longer the case that only national government can make laws within their territories.
Britain joined the EU in 1973 when it was still European Economic Community (EEC). So until 1972 UK had complete parliamentary sovereignty" but as the UK's application to join the EU was accepted, Parliament passed the European Communities Act. This Act transferred some control over creation of laws to EU institutions.
When talking about where exactly the law comes from, lawyers talk about "sources of law".
There are two sources of European Union law. There is primary and secondary.
Primary sources of EU law are treaties. Treaties are agreements signed by the Heads of State of all the member states of the EU. They set out all the main principles and goals of the EU. So far as our law is concerned all treaties signed by our head of government become part of English law automatically. This is a result of the European Communities Act 1972.
There are four main treaties of the European Union. The Treaty of Rome 1957 was when the EEC was created and trade barriers and custom duties were abolished. The Maastricht Treaty 1993 was when the EC became the EU and everybody holding a passport from one of the member states of the EU became a citizen of the EU. It also meant that that the European...