What did Flores claim in his lawsuit?

Flores is the name under which the Reno v. Flores case is known, under which it was claimed that the detention of a minor by the government was in violation of the child's rights under the Due Process Clause of the US Constitution and the Equal Protection Clause. The latter is a part of the 14th Amendment to the US Constitution, providing basically that all persons within a jurisdiction have equal protection of the laws.