Keywords: Formal and substantive concepts of law, settled application of law, legal certainty, detention of migrants
Abstract: The article comments on a recent judgment by the Court of Justice in the Al Chodor case, in which the Court of Justice concluded that the criteria of the risk of absconding, the condition for a detention of migrants, must be defined in a binding provision of general application. In the article, we analyse the judgment from the theoretical perspective, in particular with regard to the difference between the formal and material concept of law. Firstly, we summarise the argumentation of the Court of Justice, we analyse the structure of the applied norm and we describe the theoretical foundation of the formal and material concept of law. Subsequently, we critically approach the reasoning of the Court of Justice and we refute its arguments in favour of the formal approach. We emphasise the detailed doctrine behind the material concept of law incorporating among others strict requirements on the law applying institutions. Lastly, we briefly comment on the amendment of the Act on the Residence of Aliens in the Territory of the Czech Republic and on the law in other member states.