The writ of habeas corpus primarily acts as a writ of inquiry, issued to test the reasons or grounds for restraint and detention. The writ of habeas corpus, also known as the Great Writ, is a U.S. legal process that determines whether an offender's imprisonment is valid.The writ of habeas corpus is a legal order requiring a person holding another person to produce that individual before a court or judge. Habeas corpus, or the Great Writ, is the legal procedure that keeps the government from holding you indefinitely without showing cause. Federal habeas corpus is a procedure under which a federal court may review the legality of an individual's incarceration. What we are talking about, of course, is habeas corpus, a Latin phrase meaning "you should have the body. Habeas corpus is essentially a safeguard against unjust incarceration. A writ of habeas corpus is a legal order that requires the custodian to bring the detained individual before a court or judge. The U.S. Supreme Court interprets the Constitution, which means it defines constitutional rights and violations in the cases it decides. Habeas corpus is a legal rule that requires a prisoner be presented in court and that the arrester prove that there is proper cause for detaining the prisoner.