The master's thesis studies and presents an analysis of the legal regulations and their execution return of illegally staying migrants when the world and the European Union faced the most extensive migrations in modern history. The purpose of the master's thesis is to elaborate and present misdemeanour and administrative proceedings for the return of illegally staying third-country nationals. The research part encompasses sectoral legal acts of the European Union, the Republic of Slovenia, and the Republic of Croatia, who determine the procedures upon discovering established unauthorized residence. The research work also includes empirical research on issued decisions on returns, decisions on accommodation, and legal remedies against them from 2015 to 2019 in the Republic of Slovenia and the Republic of Croatia. The research of the considered field was based on various research approaches and methods of scientific research work, from the use of statistical, inductive-deductive, comparative, analytical, and synthetic methods, comparison and compilation, and the descriptive research method.
The results of the hypothesis test showed that in Croatia the entire procedure for issuing return decisions due to unauthorized residence is more comprehensively regulated compared to Slovenia, which is reflected in fewer appeals against issued decisions and a lower percentage of upheld appeals. This leads to greater efficiency in the enforcement of return decisions issued for unauthorized residence. The master's thesis represents a professional contribution in the field of misdemeanour and administrative proceedings in the established illicit residence of third-country nationals, which is handled by the Police. Therefore, it is applicable to the work of the competent authorities and further research.