Xavier Groussot

This chapter studies the evolution of the classic legislative concepts developed by the Court of Justice of the European Union (CJEU) in its free movement jurisprudence. The idea is to discuss the key decisions mentioned by Piet Jan Slot in his article (‘Harmonisation’) published in 1996 in European Law Review and analyse these decisions in a new light and a new context. In a nutshell, the chapter will constitute a horizontal study focusing mainly on the evolution of legislative concepts such as mutual recognition, minimum harmonization and total harmonization in a horizontal study. Are the old concepts still applicable in the same way? Are there new concepts appearing in the CJEU case law? Furthermore, the focus will be on the development of derogations and the impact of proceduralization. Should there be new concepts developed by the CJEU? How are unity and diversity balanced in the recent case law? Another aim of the chapter will be to discuss this evolution of legislative concepts in light of the federal idea and federalist theories. Notably, the chapter will particularly look at the theories of vertical federalism and process federalism. This is of particular interest since the theory of process federalism has, for instance, only started to grow in the 1990s, i.e., at more or less the same time of Slot’s article. Yet the Lisbon Treaty arguably provides a more viable ground than the Maastricht Treaty for the development of claims based on process federalism.