Two cases help illustrate how crucial habeas corpus has been to the development of liberty. The core meaning of the word "liberty" itself is simply freedom from bodily constraint without due process of law. For many hundreds of years in legal systems derived from English law, habeas corpus has been the main, and often the only, mechanism by which this most essential of freedoms has been enforced.
Dr. Bonham's Case, in 1610, played a key role both in the history of American and Commonwealth constitutional law and in the ending of the power of the guilds. Guilds were somewhat like labor unions or business cartels, but often with an extra power -- the power to themselves convict and imprison those operating in the guild's business.
Besides guild courts, there were a large number and variety of other franchise courts in England: church courts, merchant's courts, manorial courts, mining courts, colonial courts, municipal courts, the courts of private counties, and so on. The king's courts generally had no jurisdiction to hear appeals from franchise or military courts except by extraordinary writ -- the most important of which was habeas corpus.
Dr. Bonham was imprisoned by the London physician's guild for practicing medicine in London without their license. Habeas corpus made it possible for Dr. Bonham to appeal his imprisonment. The Court freed Dr. Bonham, holding that his due process rights had been violated by the guild: the guild's conviction had not been obtained before a proper court.
Somerset's Case, in 1772, played a crucial role in the abolition of slavery. Somerset was a (former, it was argued) slave (formerly) owned by a merchant from the American colonies. When Somerset escaped from his master, he was recaptured and put on a boat for the British territory of Jamaica. An abolitionist petitioned on Somerset's behalf for habeas corpus, which Lord Mansfield granted. Still on the high seas, the writ of habeas corpus ordered the British captain to bring Somerset to London to be produced before the King's Bench. Slavery was no ordinary kind of property: it was also a deprivation of bodily liberty. As such, habeas corpus made it possible for the slave to challenge his status as bodily detained property. The high court's writ of habeas corpus reached far beyond Great Britain to the United Kingdom's colonies and its ships as sea. Once Parliament banned slavery across the British Empire, the Great Writ was crucial in implementing the ban to abolish slavery throughout that globe-spanning enterprise.
The Great Writ has been often been suspended in areas and periods of warfare, leading to great abuse but also to the ability to efficiently and ruthlessly fight the war without the legal overhead. The U.S. Constitution specifies that habeas corpus may be suspended only by Congress, and only with respect to invasion or rebellion (it may not be suspended domestically due to a foreign war or mere domestic crime), and even then only so long as public safety requires the suspension. Article I (listing the powers of Congress) states:
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. Art. I, Â§9, cl. 2.More about the habeas corpus , military detention, and the Military Commissions Act coming soon in a subsequent post.
UPDATE: Here are some subsequent posts on habeas corpus and the MCA:
The Lex Gabina: ancient Military Commissions Act?
Liberty and habeas corpus (II)