The differences between habeas corpus and due process are important. The Due Process Clause, among other things, regulates the procedures that the government must use before it detains a person and holds the person in custody. But the Suspension Clause safeguards a more elemental habeas privilege. That is, under the Suspension Clause, the judge examines the bare question of whether a person is being held in custody legally. In Habeas Corpus and Due Process, I focus on the independent role of the habeas process. The deep confusion between habeas corpus and due process arises from a critical area of overlap: the habeas judge may examine not only the bare lawfulness of the custody, but also whether officials complied with required procedures to detain the person, including due process requirements.
Brandon L. Garrett, Habeas Corpus Standing Alone: A Reply to Lee B. Kovarsky and Stephen I. Vladeck, 98 Cornell Law Review Online 35-42 (2013)