The essays comprising this volume are the outcome of a major and unique project which looks in detail at the application of EC law by national courts and the interaction of the demands of EC law with the constraints imposed by national legal orders and,especially, national constitutional orders. The volume comprises seven country studies which are shaped around a common research protocol. These are supplemented by three cross-cutting studies which draw on the country studies as well as on broader contextual research work aimed at trying to understand the role of the European Court of Justice in the round.The results of this multi-national research are certain to provoke widespread interest among scholars of European law, international law and European politics, for they offer the first systematic and rigorous attempt to assess the impact of the ECJ among the leading member states of the European Union.