Brexit as a hybrid phenomenon, that is, both legal and socialpolitical, is the next stage in the debate on the place and role of the European Union. The analysis of the impact of European legislation on the shape of British constitutional law requires establishing the admissibility of reversing existing constitutional modifications. The author will argue that in the age of globalisation and establishing legal network links, the participation of states in supranational organisations can result in irreversible modifications of the scope and meaning of constitutional law. In a simplified way, individual legal systems in a legal pluralism are “open”. The changes taking place are irreversible because they concern the foundation of competences as well as the systemic position of individual national authorities.