This article aims to present the legal regulation contained in the Constitution of the Republic of Poland, which allowed Poland to join the European Union. The scope of the regulation contained in Art. 90 of the Constitution of the Republic of Poland provided the minimum and at the same time sufficient grounds for the accession; however, this norm does not specify all issues that may need clarification. The basic defects of Art. 90 include the use of unclear concepts that may raise doubts in the process of their application. Criticism was levelled particularly at the lack of unambiguous specification of the substantive limits of non-transferable competences. The cited provision of the Constitution of the Republic of Poland states only that the “transfer” may not include entire competences of certain bodies (for example, legislative, executive, or judicial), but only the competences of these bodies in certain matters.
In the light of this very imprecise way of defining the limits of the competences to be delegated, the only available way to define the limits of the delegated competences is referring to the axiological values on which the Constitution of the Republic of Poland is based. The article also emphasizes that nowadays, after numerous years of Polish membership in the EU, and after the introduction of the provisions of the Treaty of Lisbon, which significantly changed the principles of the functioning of the EU, it is necessary to make appropriate amendments to the Constitution of the Republic of Poland.