One of the fundamental values of any legal system is the principle of certainty of law, whose highest expression is its encoding in the various bodies of law. However, today this value is strongly, albeit inadvertently, called into question by the European Union - in particular, by a set of principles, and related mechanisms, designed to ensure uniformity of law across the EU Member States. These include the principle of primacy of EU law over the laws of its Member States, the principle of the disapplication of national laws that are incompatible with EU law (including the provisions of directives that have not yet been implemented, or that have implemented in a manner deemed incorrect), the principle of interpretation of national law in conformity with EU law and, above all, the conclusive and binding effect of the judgments of the EU Court of Justice even when they provide a 'unique' or unusual interpretation, not expressly provided for in EU law. These principles are now well-established benchmarks in supreme and national courts as well, to the extent that there has been a radical shift in the system and hierarchy of sources of law in each legal system of the EU Member States, at the expense of citizens, businesspeople and legal practitioners, who all find it hard to identify the exact rule to apply to specific cases.