The primacy of Community law over domestic law was established as early as 1964 (see Costa v E.N.E.L, ECJ on 15th July 1964, a case from Itlay in which the ECJ introduced the doctrine of the primacy of Community law). It is now clear that EC/EU law takes priority over the law of Member States if there is inconsistency between them (see eg Marleasing SA v La Comercial Internacional 1992 1 CMLR 305 (ECJ Case C-106/89).

If in any respect British law is incompatible with applicable European Community law, then an individual who suffers loss as a result may be able to claim compensation from the British government under the principle in Francovich v Republic of Italy ECJ 1995 ICR 722, ECJ.

This result is unlikely both because the British government normally goes to considerable trouble to ensure that British law conforms with EC directives and because the British Courts will resolve any ambiguity in the wording of a British statute in a way which is consistent with EC law and interpret British law in a way which is consistent with applicable EC law unless the wording of the British provision make this impossible. The British Courts are even prepared actually to insert ("interpolate" is the expression used) wording into a UK statute if that is the only way to ensure conformity with EC law, provided the interpolated wording is not contrary to the wording actually used in the UK statute and is "compatible with the underlying thrust of the legislation".

Nevertheless, there are several examples of cases in which British law has been held to be unenforceable because it is inconsistent with EC Directives (see for instance Levez v T.H. Jennings (Harlow Pools) Ltd 2000 ICR 58, EAT).