Habeas corpus is also known as the Great Writ as it preserves the constitutional right to be protected against unlawful imprisonment. Habeas corpus is a Latin phrase meaning "produce the body.Federal habeas corpus is a procedure under which a federal court may review the legality of an individual's incarceration. Habeas corpus is essentially a safeguard against unjust incarceration. What we are talking about, of course, is habeas corpus, a Latin phrase meaning "you should have the body. Habeas corpus is a legal action in which a prisoner challenges the authority of the jail or prison to continue holding him. Filing a petition for habeas corpus means that you are arguing that your incarceration is unjust. In a petition for habeas corpus, a prisoner (or another interested party) raises doubts about the legality of his or her imprisonment. Habeas corpus prevents the King from simply locking up subjects in secret dungeons and throwing away the key. The U.S. Supreme Court interprets the Constitution, which means it defines constitutional rights and violations in the cases it decides.