This paper aims to use the jurisprudence of the Court of Justice of the European Union to show the importance of a difficult journey that began with the Van Duyn v. Home Office (1974) C-41/74 which this year marks 50 years. The direct effectiveness or direct effect of directives has been a topic that has tortured jurisprudence as well as doctrine for many years since it was synonymous with the justiciability that addressed the process of European integration as well as the private enforcement of the EU for the protection of private individuals. The many rights, the still new innovations, the open problems and the path taken up to today still shows that the constitutional architecture of the EU continues in the sector of the primacy of the law of the EU.