Habeas corpus

Habeas corpus (literally, "that you have the body [the subject person under detention]") is a writ, or legal action, through which a prisoner can be released from unlawful detention. The remedy can be sought by the prisoner or by another person coming to his aid. Habeas corpus originated in the English legal system, but it is now available in many nations. It has historically been an important legal instrument safeguarding individual freedom against arbitrary state action.

A writ of habeas corpus is a summons with the force of a court order, addressed to the custodian (a prison official, for example) demanding that a prisoner be taken before the court, and that the custodian present proof of authority, allowing the court to determine if the custodian has lawful authority to detain the person. If the custodian does not have authority to detain the prisoner, then he must be released from custody. The prisoner, or another person in his or her behalf, may petition the court, or a judge, for a writ of habeas corpus. One reason for the writ to be sought by a person other than the prisoner is that the detainee might be held incommunicado.