Habeas corpus—also known as the Great Writ—is the legal procedure that prevents the federal government from arresting and holding (in prison) a person indefinitely without showing cause for detaining the person. This Latin term is pronounced "Hay-bee-us Corp-us."

A person detained by the federal government may challenge their detention by filing a habeas corpus petition—which then requires the government to explain to a neutral judge the justification for detaining the person. A habeas petition is prosecuted or litigated as a civil (noncriminal) matter against the government agent (usually the prison warden) who holds the defendant in custody.

The Founders of the United States who wrote the U.S. Constitution believed so strongly in this protection against government overreach they included it in the first article of the Constitution (Article I, Section 9, Clause 2).

In Mississippi, as in all states, habeas corpus is a fundamental legal procedure protected by both federal and state law. It serves as a safeguard against unlawful detention by the government. Under Article I, Section 9, Clause 2 of the U.S. Constitution, the right to petition for a writ of habeas corpus is a protection against indefinite imprisonment without just cause. When a person is detained by the federal government, they can file a habeas corpus petition, which obligates the government to provide a valid legal reason for the detention to a neutral judge. This process is civil in nature and is typically directed against the government official responsible for the detainee's custody, often the prison warden. The right to habeas corpus can only be suspended in cases of rebellion or invasion where public safety may require it. Mississippi state statutes also provide for habeas corpus procedures, ensuring that individuals within the state have the right to challenge unlawful detention.