Constitutional courts (CCs) are more and more often facing situation in which the status of entities of legal relation escapes public – private distinction. The reasons for this include i.a. the fact that states delegate their tasks to private actors and use private legal forms of action. On the other hand, in the relations between private entities we have often to do with a significant economic or social dominance of one of them, which disturbs the balance between them. To ensure efficiency of fundamental rights CCs develop different instruments that make it possible to apply constitutional provisions also in formally private relations. In this way, CCs play an active role in publicization of private relations. The analysis of the judicial decisions of CCs in particular countries proves that despite significant differences between their legal systems and tools used by CCs (Drittwirkung, state action theory etc.) the mechanism of this publicization is based on universal argumentation.