What is the test for a claim under the Fourth Amendment where a child has been "seized" by the police?

² "Where a particular Amendment provides an explicit textual source of constitutional protection against a particular sort of government behavior, that Amendment, not the more generalized notion of substantive due process, must be the guide for analyzing these claims." County of Sacramento v. Lewis , 523 U.S. 833, 842, 118 S.Ct. 1708, 140 L.Ed.2d 1043 (1998). Therefore, because the Fourth Amendment provides a bulwark against unreasonable seizures, children who have been "seized" must pursue their claims under the purview of that specific constitutional provision.