The paper focuses on the issue of state citizenship (nationality) of individuals. States regulate who are their nationals.
Particular attention is paid to the state citizenship of the First Czechoslovak republic and the Czech Republic. The paper analyses the requirements of international law in respect to nationality.
The focus is laid on the real bond between the state and an individual (natural person) and on possible consequences in case of not fulfilling the requirement of the genuine link. The paper also deals with the topic of dual citizenship (nationality), including the dual citizenship in the Czech Republic from the perspective of international law.