The value of “precedent” in the case law of the Court of Justice of the European Union and the attempt to identify its characteristics within the European Union legal framework cannot be proceeded without the preemptive analysis of the legal reasoning and of the creative role of the judge. The role of the precedent in the legal reasoning and in the interpretation of the European Union law, as well as the unanimously accepted capacity of the judge to “create” law, are to be indented as the pivotal conditions allowing the development of a stare decisis system. The second part of the present thesis is focused on the peculiar features of the judicial precedent in the case law of the Court of Justice. In particular, we could notice, firstly, the absence of a clear definition and distinction between the concept of ratio decidendi and obiter dicta; secondly, we underline the need to overcome the classical distinction between persuasive precedent and binding precedent, in order to properly evaluate the scale of value that the precedent can take following the use and the function that is playing from time to time. Moreover, the analysis of the efficacy of the precedent will be confined, in this second part of the work, to the “self-precedent” of the Court, meaning to the obligation for the judge to follow his own precedent. The analysis will then highlight the role of precedent in case it is overruled or distinguished by the Court: practice that, ultimately, has to be conceived as a confirmation, as well as a recognition, of the precedent’s value. Furthermore, in spite of the absence of a doctrine of precedent in the European Union legal system, we recall two circumstances in which the judicial precedent assumes a de facto binding value. Firstly, we analyse the use of precedent in the decision-making activity of the judge, and then those norms of the rules of procedure that required the Court of Justice to decide by explicit reference to the previous judgment. Lastly, the analysis will be focus on the efficacy of the Court’s precedent with respect to the Tribunal is the evaluation of the impact of the vertical relationship between the two judges and the extension to which the Tribunal is bound by the Court’s as well as in the relationship between the Court and the national judge.