This book, published in two volumes, is based on the contributions made to the W.G. Hart Workshop 2003. It contains more than forty contributions by leading experts seeking to assess the state of development of EU law some fifty years after the establishment of the Communities and contribute to the current debate on the European Constitution. The first volume concentrates on the theme of European Constitutionalism and analyzes the proposed Constitution dealing, among others, with the division of competence between the EU and the Member States, Community legislation, the role of the national parliaments, democracy in the EU, and the Court of Justice. The second volume focuses on challenges in the field of the internal market and external relations, looking at diverse areas of European law, including free movement, competition law and merger control, public procurement, consumer law, enlargement, WTO, third country nationals, and sex equality. Authors include: Tony Arnull, George Bermann, Marise Cremona, Paul Craig, Eileen Denza, Piet Eeckhout, Koen Lenaerts, Steve Peers, Wulf-Henning Roth, Francis Snyder, Erika Szyszczak, Takis Tridimas and Stephen Weatherill.