The Factortame litigation led to a series of landmark decision

Landmark decision

Landmark court decisions establish new precedents that establish a significant new legal principle or concept, or otherwise substantially change the interpretation of existing law...

s in United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 (UK) and European Union

European Union

The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...

 (EU) law. The case confirmed the supremacy of European Union law

European Union law

European Union law is a body of treaties and legislation, such as Regulations and Directives, which have direct effect or indirect effect on the laws of European Union member states. The three sources of European Union law are primary law, secondary law and supplementary law...

 over national law in the areas where the EU has competence

Principle of conferral

The principle of conferral is a fundamental principle of European Union law. According to this principle, the EU is a union of member states, and all its competences are voluntarily conferred on it by its member states...

. The decision, which formed part of a lengthy litigation battle comprising numerous judgments spread over a period of more than ten years, raised a number of issues which are of particular constitutional significance in the debate in the UK over the purported erosion of parliamentary supremacy.