This book contributes to the debate about the impact of European Community Law on the national constitutional orders and cultures of the respective Member States. The author examines the doctrine of sovereignty as a mechanism within which this impact may be best assessed and in particular how it underwrites the tension between European Union rights and the rights provided by the respective legal orders of the Member States. In particular the book focuses on political, social and civil rights, drawing from T.H. Marshall's typology. In endorsing an appropriate analytical framework, the book challenges both existing law and secondary literature in order to argue that the terminology, the concepts and the tools which are used to assess the impact of the EC law on the national constitutional orders are to be selected with great care. This is particularly apposite given the complexity of constitutional diversity, in terms of national constitutions and their reception of EC law. It is also important because of the variety of approaches involved in the constitutional adjustment of the acquis of the Union within the context of the increasing drive to constitutionalisation of the Union on the one hand and enlargement on the other.