The European Court of Human Rights has decided three times on the rights of foreign unaccompanied minors (H.A. and others v. Greece, KHAN v. France, May 2019, and Moustahi v. France, June 2020). In these cases, the Court has stated that the first obligation of States is to take the necessary measures to identify minors, particularly at the border, so that this identification is an essential precondition for any decision. In case of uncertainty, the presumption of the minority must be applied so that “in the hypothesis that the person is a minor, he/she is treated as such”. Incorrect identification, according to these rulings, can lead to a violation of art. 3 ECHR. This contribution will focus on the main lines of the Strasbourg case law concerning migrant children moving alone, emphasising the need to bear in mind the child's highly vulnerable situation. This element must take precedence over any other.