The two sources of law so far discussed – legislation and judicial decisions – dominate the field of law-making within the United Kingdom system. But there are other sources of law for the United Kingdom of which by far the most important is European Union (previously European Community) law. The chapter deals also with textbooks and custom as sources of law and with various forms of quasi-legislation.

European Union Law

European Community law became part of the United Kingdom system as from 1 January 1973 the day on which the United Kingdom became a member of the European Communities. On the international plane this was by virtue of joining the Treaty of Paris of 1951 establishing the European Coal and Steel Community and the two Treaties of Rome of 1957 establishing Euratom and the European Economic Community (EEC).

Since 1957 the system has been in a state of evolution with especially significant developments being the Single European Act of 1986, the Treaty of Maastricht 1992 (known as the Treaty of the European Union or TEU), the Treaty of Amsterdam of 1997 which, inter alia, renumbered the Treaty provisions, and the Treaty of Nice of 2001. Under the Treaty of Maastricht the EEC was renamed the European Community (EC) and the geographical unit formed by the then fifteen Member States became the European Union (EU).