The legislation of the Republic of Croatia enables foreigners to initiate an administrative dispute against the decision of the Ministry of the Interior, which applied some of the measures to ensure return because they were caught illegally crossing the border or illegally staying in the Republic of Croatia. The first part of the paper explains the concept of the state border and the Schengen area with special emphasis on the division of borders into external and internal. Given that it is a member of the European Union and the Schengen area, one of the main strategic goals of the Republic of Croatia is the protection of external borders. This activity is carried out as part of supervision of the border in addition to the activity of border control. Then the term foreigner is explained, i.e. the categories of foreigners in the Republic of Croatia are listed, stating the conditions for their entry and stay in the country. Furthermore, the concept of illegal entry and stay of foreigners is clarified, the measures taken by the competent authorities in these cases and how certain categories of foreigners are treated are mentioned. Then the paper explains the first instance administrative dispute, the manner and conditions of initiation, the principles, the court's conduct upon receipt of the lawsuit, the concept of a quasi-administrative dispute, the decisions of the administrative court and the administrative appeal dispute. Finally, the concept of a constitutional lawsuit, as a special institute, and the concept of the Constitutional Court, as a special state body which ensures the protection of constitutionally guaranteed human rights and fundamental freedoms, is clarified. In conclusion, a brief overview of the case law relating to the restriction of freedom of movement and illegal stay follows.