It is generally accepted that law consists of two main domains – private and public. At the same time, there is clear scepticism about the sharp separability of these domains. The problém of distinguishing private and public law is undoubtedly also a problem of public administration and its implementation as it is possible that the public purpose will also be fulfilled by private law norms. In addition, there may be legal institutes that combine more or less the norms of public and private law, for which the designation of hybrid legal institutes seems appropriate. However, such institutes may present some difficulties associated with legal dualism. The aim of this two-part paper (within its limited scope) is to provide a basic introduction to the issue of socalled hybrid legal institutes. In the first part of the paper, besides some general background, the text presents a triad of such institutes that are applied in the context of public administration and for which some debate over their legal nature could be observed in the domestic literature. In the second part (which will be published in a future issue of the journal), the text attempts to answer the research question of how to deal with these institutes, or rather considers some basic criteria for distinguishing private and public law in the context of public administration regulation.