in English language: The statement of Angela Merkel from November 2014 that she would rather see the UK out of the EU than compromise the free movement in the EU (which as at the date of the submission of this dissertation materialized in potential Brexit) was one of the reasons which encouraged the author to analyse the reach of free movement rules, more specifically the horizontal direct effect of the Treaty freedoms, in this dissertation. The author focuses on the issues stemming mainly from the broader topic of the legitimacy of market integration which the author translated into the concept of separation of the regulatory competences between the EU and the Member States and related separation between the Treaty provisions' addressees, namely the Member States and the private entities. This dissertation focuses on the following research question: To what extent has the CJEU advanced the European market integration through the development of the principle of horizontal direct effect of the Treaty freedoms? The starting point after the establishment of the EEC was that the sole addressees of the Treaty freedoms were the Member States whereas the Treaty rules on competition only applied to private entities. However, as is demonstrated throughout this dissertation, it is nowadays generally accepted...

L’objectif de cette recherche est d’évaluer la contribution du principe de non-discrimination à l’identité constitutionnelle de l’Union européenne. Pour ce faire, il est nécessaire de clarifier la notion d’identité dont nous parlons. Dans la première section/partie nous analysons la structure des arrêts pour juger sur la discrimination. La structure de l’arrêt sur la discrimination permet, après une phase initiale d’ajustement dont nous avons signalé, d’identifier quatre phases différentes au sein desquelles la Cour de justice développe son raisonnement. Ces phases sont : 1) introduction de l’affaire devant la Cour de justice de l’Union européenne 2) identification du désavantage 3) comparaison et 4) justification. La deuxième section/partie porte sur l’analyse de la contribution à l’identité constitutionnelle de l’Union européenne par la lutte contre sept motifs spécifiques de discrimination : sexe, nationalité, handicap, âge, religion, orientation sexuelle et race. Le choix des motifs de discrimination (par exemple, entre les beaucoup plus nombreux motifs dans la Charte des droits fondamentaux de l’Union européenne) est lié à un critère normatif : ce sont les motifs de discrimination qui ont fait l’objet de la législation dérivée. D’où il suit un critère supplémentaire, celui quantitatif : la présence d’un acquis législatif stable autorise la Cour de justice à saisir un plus grand nombre des causes, qui font significative l’examen des motifs proposés. L’identification d’une contribution si riche à l’identité constitutionnelle de l’Union européenne peut reconnaître le principe de non-discrimination en tant que principe constitutionnel, qui, inspiré par l’identité constitutionnelle des États membres, peut constituer l’épine dorsale de la future constitution "formelle “européenne. / The definition of the EU as a constitutional legal order is crucial, but still fragmented. For the sake of systematization, it is important to find out a principle to support its development. That is why we made the choice of examining the principle of non discrimination through the analysis of case law, with the object of verifying if this principle is a fundamental part of the EU constitutional identity. In the first part of this work the structure of the discrimination scrutiny in front of the CJEU and of the ECHR is analyzed, enlightening the fact that its structure increasingly recalls that of a constitutional scrutiny. In the second part of this work we will focus on the contribution given by the case law on the fight against different grounds of discrimination to the EU constitutional identity. As there is an increasing number of grounds of discrimination, a choice should be made. That is why the second part of the analysis is devoted into explaining a selection of grounds of discrimination: discrimination on the ground of nationality, age, disability, religion, and sexual orientation. From the analysis of the case law and of secondary legislation is possible to induce that this principle has the potential necessary to support the development of the EU constitutional identity without prevailing on the national constitutional identities. At the same time, the principle could help into shading light in one of the most debated issues of EU law: the tension between the conferred powers and the direct effect of directives. The conclusion of this work is a reflection on how a precise line of case law is crucial into defining the principle of non discrimination as a EU constitutional principle.