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 Minnesota, 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 federal government is prohibited from suspending the writ of habeas corpus except in cases of rebellion or invasion where public safety may require it. A person in federal custody in Minnesota can file a habeas corpus petition to challenge the legality of their detention. This petition is filed in a federal district court and requires the government to present a valid legal basis for the individual's imprisonment. If the detention is found to be without sufficient legal cause, the court can order the person's release. The process is civil in nature and involves the person detained (the petitioner) and the government agent responsible for the detention (usually the prison warden), who is named as the respondent. Minnesota state statutes also provide for habeas corpus under state law, allowing individuals detained by state authorities to similarly challenge their detention in state courts.