Produce the Body, Explain the Cage
Habeas corpus is a legal procedure that calls on a court to review an allegedly unlawful detention. It requires the prisoner's custodian, usually a prison official, to bring that person before the court so a judge can decide whether holding them is lawful at all.
The name is blunt. It comes from the Latin *habeās*, meaning to have or to hold, used here in the sense of to produce or bring forward, and *corpus*, meaning body. Produce the body.
It is enforced through a writ, and belongs to a class known as the extraordinary, common law or prerogative writs, historically issued by English courts in the name of the monarch to keep inferior courts and public authorities in check. The most important detail is the direction the burden runs: at common law it was usually the official who had to prove the detention was authorized, not the prisoner who had to prove it was not.
Older Than Magna Carta
Habeas corpus is routinely credited to Magna Carta in 1215. The foundations are in fact "wrongly thought" to have originated there, and actually predate it, stemming from the Assize of Clarendon of 1166 during the reign of Henry II.
The eighteenth-century jurist William Blackstone cited the first recorded use of *habeas corpus ad subjiciendum* in 1305, under Edward I, though writs with the same effect were being issued as early as Henry II's reign more than a century before. Blackstone explained the underlying logic in royal terms: "the king is at all times entitled to have an account, why the liberty of any of his subjects is restrained, wherever that restraint may be inflicted."
He also gave it the description that stuck, calling it a "great and efficacious writ in all manner of illegal confinement". To this day it is still universally known and celebrated as the Great Writ of Liberty.
The Parliament That Was Dissolved For It
The procedure was first properly codified by the Habeas Corpus Act 1679, passed after a series of judicial rulings had chipped away at the writ's effectiveness. An earlier law, the Habeas Corpus Act 1640, had already been needed to overturn a ruling that the command of the king was itself a sufficient answer to a petition for habeas corpus.
The 1679 Act was not a calm piece of legal housekeeping. It was passed amid a sharp confrontation between King Charles II and a Parliament dominated by the sharply oppositional, newly formed Whig Party. Whig leaders had good reason to fear the king moving against them through the courts, as indeed happened in 1681, and regarded habeas corpus as protecting their own persons. The short-lived parliament that passed it became known as the Habeas Corpus Parliament, and the king dissolved it immediately afterwards.
Writing in 1885, the jurist A. V. Dicey judged that the Habeas Corpus Acts "declare no principle and define no rights, but they are for practical purposes worth a hundred constitutional articles guaranteeing individual liberty".
A Right With an Off Switch
For all its status, habeas corpus has limits, and the most serious is that it can be switched off. It has been temporarily or permanently suspended on the basis of war or a state of emergency, as with Britain's Habeas Corpus Suspension Act 1794 and the United States Habeas Corpus Suspension Act of 1863.
The US Constitution addresses this directly in the Suspension Clause, at Article One, Section 9, which states that "The privilege of the writ of habeas corpus shall not be suspended, unless when in cases of rebellion or invasion the public safety may require it". Presidents Lincoln and Grant suspended it in places during the Civil War and Reconstruction, and Franklin D. Roosevelt suspended it during the Second World War. Following the September 11 attacks, an attempt to place Guantanamo Bay detainees outside habeas jurisdiction was overturned by the Supreme Court in *Boumediene v. Bush*.
There is also a quieter limitation. Because the writ only examines whether a detention is lawful, a petition fails whenever the detention is authorised by statute, which is how internment without trial has coexisted with the writ remaining technically available.
