The study of the European integration process offers a serious challenge for the social sciences. It is easy to understand why the disciplines of law, economics, and political science have made the most relevant contributions to the study of the Europeanization of our societies. From the treaty creating the European Coal and Steel Community in May 1951 to the establishment a few years later of Euratom, from the treaty of Rome to the European Economic Community (EEC), from the European Single Act to the Maastricht treaty and the Monetary Union, from the treaties of Amsterdam and Nice to the recent Convention that resulted in the proposal for a European Constitution, all of these historical events during the second half of the twentieth century mark a process of transferring sovereignty rights from nation-states to European institutions. The Council, the Commission, the Parliament, and the European Court of Justice are substantial innovations from the point of view of public law. They are not ‘state institutions’, nor are they intergovernmental agencies. In many domains, the influence of European regulations on national legislation is impressive. The amount of literature in all languages on the legal aspects of European integration is astonishing.