This article presents the current conceptions of European integration through law. It describes the contributions and the weaknesses of the three ways in which law can facilitate european integration and shows that none appears able to reach the desired result. The first conception, legislative unification, is the official doctrine supported by the European Communities and has been for the past century the favoured unification device in most of the world. An examination of the numerous hindrances to its efficiency helps explain the difficulties it encounters. The second, quite recent, conception consists in the application and teaching of a technique to understand the law. It offers a new approach based on sociological analysis ; however it...