A writ of habeas corpus (Latin: “you should have the body”) is a common law order issued by a judge or court requiring the appearance of a prisoner or detainee before the court for a specified purpose. The most common and important purpose of a such a writ is to determine the validity of a person’s arrest, imprisonment, or detention under relevant laws or constitutional provisions. The habeas corpus remedy is recognized in the countries of the Anglo-American legal system but is generally not found in civil-law countries, although some of the latter have adopted comparable procedures.

The origins of the writ of habeas corpus cannot be stated with certainty. Before the Magna Carta (1215) a variety of writs performed some of the functions of habeas corpus. During the Middle Ages writs of habeas corpus were employed to bring cases from inferior tribunals into the king’s courts. The modern history of such a writ as a device for the protection of personal liberty against official authority may be said to date from the reign of Henry VII (1485–1509), when efforts were made to employ it on behalf of persons imprisoned by the Privy Council. By the reign of Charles I, in the 17th century, a writ of habeas corpus was fully established as the appropriate process for checking the illegal imprisonment of people by inferior courts or public officials.

Many of the procedures that made for the effective assertion of these rights were provided by the Habeas Corpus Act of 1679, which authorized judges to issue writs when courts were on vacation and provided severe penalties for any judge who refused to comply with it. Its use was expanded during the 19th century to cover those held under private authority. In 1960 legislation was enacted limiting the instances in which a writ of habeas corpus could be denied and establishing new lines of appeal.

In the British colonies in North America, by the time of the American Revolution, the rights to writs of habeas corpus were popularly regarded as among the basic protections of individual liberty. The U.S. Constitution guarantees that the privilege “shall not be suspended, unless when in cases of rebellion or invasion the public safety may require it” (Article I, Section 9, paragraph 2). In England such suspension had occurred during the wars with France at the time of the French Revolution. In the United States, Pres. Abraham Lincoln suspended the writ by executive proclamation at the outbreak of the Civil War in 1861. The presidential act was challenged by Chief Justice Roger Taney who, in the case of Ex parte Merryman, vigorously contended that the power of suspension resided only in Congress. Lincoln ignored the order of the court, but the weight of modern opinion appears to support Taney’s view.

The modern uses of writs of habeas corpus in the United States have been quite varied. In the mid-20th century the U.S. Supreme Court’s expansive interpretation of the constitutional rights of those accused of crime led to the filing of many habeas corpus petitions by prisoners, challenging their convictions. That interpretation was gradually narrowed by the Supreme Court and by congressional acts in the later years of the century.

In contemporary law a writ of habeas corpus is frequently requested on behalf of one in police custody for the purpose of requiring the police to either charge the arrested person with an offense or release that person. Habeas corpus proceedings may be employed to obtain release of an accused individual prior to trial on the ground that the bail set is excessive. On occasion habeas corpus relief has been granted to prisoners who are unlawfully detained after the expiration of their sentences. In cases of persons arrested under a warrant of extradition, a proceeding in habeas corpus may be instituted to challenge the validity of the warrant.

The writ of habeas corpus may also be employed in a wide variety of situations not involving criminal proceedings. Thus, competing claims to the custody of a minor may be adjudicated in terms of habeas corpus. Someone confined to a mental hospital may in some jurisdictions bring about release from the hospital by demonstrating the recovery of sanity at a habeas corpus hearing. In 2004 the Supreme Court held in Rasul v. Bush that a writ of habeas corpus is available to an alien held by the military as an enemy combatant in territory outside the U.S. but under its control. In Boumediene v. Bush (2008), the Supreme Court struck down the Military Commissions Act of 2006, which had barred foreign enemy combatants held by the United States from challenging their detentions in federal courts. In 2025, the second Trump administration indicated its desire to unilaterally suspend the right to request a writ of habeas corpus for detained immigrants who have entered the country illegally.

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