The ECJ has stood firmly since the early decades of European integration sustaining the autonomy of the (currently) EU legal order, even when only economic communities existed. In defence of the autonomy of the EU legal order, the ECJ construed a set of principles that hardly could be seen in the wording of the treaties but constitute with the case-law of the ECJ a sort of tradition that springs from the original goals and purposes of the European integration, thus uniting EU and the member States of the EU in a harmonic way. The role of the ECJ in providing the interpretation—although not immutable—of EU law, whether springing from “written form or in the form of Tradition” provides the Court with a specific authority that ought to be accepted with harmony at member States level in order to prevent a paradigm shift in the future. In particular, we have analysed the role of the Court of Justice in establishing the interpretation of EU law, without prejudice to the instruments and principles laid down in the treaties, in particular the institute of preliminary rulings (article 267 TFEU). The European depositum fidei only makes sense if it serves the treaties and the underlying program therein enshrined and if the teachings and directives are received with docility. The contrary would be autarchy, expression that “refers to a government in which a single [entity] exercises absolute control over all citizens and every aspect of their lives” and “attempts to be completely self-reliant”.