The studies, debates and suggestions collected in this volume are the result of an international conference on European Law held in September 2000, organized by the T.M.C. Asser Institute in The Hague, in cooperation with the Constitutional and Legal Policy Institute COLPI, Budapest, Hungary. The subject of the conference concerned the impact of the enlargement of the European Union on the constitutional provisions of both levels of legal order: the national and the European level. The contributors, coming from Member States as well as all candidate countries, are representatives and legal experts from national governments, from the EC Institutions, the national judiciary and the academic world (European and constitutional law). The contributions are preceded by a Report on the Conference and followed by Conclusions and Summing up of the Conference. The Annexes include, a.o., documents from the European Council of Nice (December 2000).