|│ The existence of the European Union and its legal order has often collided with the traditional concepts of the State and international law until the middle of the 20th century. Most scholars do not attempt to define the Union, but look for the differences between it and the State or other international organizations. Similarly, there are also analogous attempts to identify the characteristics of European Union law. These exact ambiguities motivated individual countries to cope with the phenomenon of transferring of the competences to the European level in their national law. While the relationship between national and international law and the related issue of sovereignty has been resolved a relatively long time ago, the establishment of European integration brings a new form of this problem. In all constitutions of the Member States of the European Union, the relationship to this integration is solved in some form, either by referring to the international organization or institution, without it being specified, or, on the contrary, by expressly discussing that relationship. The reason for the choice is not clear in most cases. An important role in relation to European Union law is played by the constitutional tribunals of the Member States, which are supposed to keep the protection of the national constitutions and also to ensure the obligations of the States resulting from the membership within the European Union and the conformity of the national values with the values of the European Union. The subject, which determines the concrete extent of the delegation of the competences, is, in the final instance, the Court of Justice. Thanks to its case-law, it sometimes makes the boundary determined by the mentioned clauses very obscured and unstable. The core of this article is devoted to the analysis of so-called integration clauses in the constitutions of the Member States, on the basis of which it can be concluded, that their formulations are various. It deals with the significant aspects within the individual countries, such as the nature of their legal order, the time when the amendment of the constitution was made, and also by a range of other, sometimes also rather subjective circumstances, such as the current political situation in the given country and attitudes of their inhabitants to the integration which caused such a plurality of adjustments.