Habeas corpus literally translates as "That you have the body." In United States law, state and federal courts issue writs, or legal actions, of habeas corpus to determine the legality of an individual's imprisonment. They do not guarantee protection from unlawful arrest, but from indefinite, illegal detention.
Article One, Section Nine of the United States Constitution guarantees the right of prisoners to writs of habeas corpus except in cases of rebellion or invasion where the public safety requires its suspension. President Abraham Lincoln unilaterally suspended habeas corpus during the Civil War. In 1942, eight German saboteurs were captured on American soil and ruled to be enemy combatants by the Supreme Court, making them ineligible for habeas corpus.