Suspension of habeas corpus is the revocation of the legal right to demand that the imprisonment of a person be proved legal by those holding the prisoner. This is usually a temporary measure, though in some cases it has been a prelude to more radical or long-lasting measures. In British law and legal systems descended from it, such as that of the United States, a writ of habeas corpus is a legal order requiring that a prisoner be brought before a court so that a judge may rule on the legality of his or her imprisonment and order the prisoner released if he or she has been held unlawfully. Many civil law jurisdictions have similar procedures. Historically, governments that usually acknowledge a right to habeas corpus petitions have sometimes suspended it, usually in response to a real or perceived threat due to war or civil disorder. Many countries' legal systems allow the suspension of habeas corpus under certain circumstances.
In the United States of America, both the right to habeas corpus and the government's power to suspend it are enumerated in Article One of the Constitution, which describes the composition and procedures of Congress and enumerates its powers. Article One, Section Nine states that the Congress is allowed to suspend habeas corpus only when it is deemed necessary for public safety “in Cases of Rebellion or Invasion.” Originally, this was taken to refer only to prisoners of the federal government, with the legal rights of those imprisoned by state governments defined by each state's own constitution, but federal courts were given the power to review petitions from prisoners held by state governments by a statute passed in 1867.
The first federal suspension of habeas corpus in America occurred during the Civil War in 1861, when President Abraham Lincoln ordered that it be suspended in some parts of the United States, such as Maryland, that were thought likely to secede and join the Confederate States of America. This was ruled illegal by a federal court, as the Constitution vested the power to suspend habeas corpus in the legislature and not the executive, but was carried out anyway. Habeas corpus was also suspended in the Confederacy during the war.
Habeas corpus was suspended on several subsequent occasions. President Ulysses Grant ordered suspension of habeas corpus in parts of South Carolina in 1870 as part of a federal campaign to suppress the Ku Klux Klan. During the Second World War, it was suspended in Hawaii after the Japanese attack on Pearl Harbor and restored in 1944. The Military Commissions Act of 2006 suspended the right of habeas corpus for aliens being held as enemy combatants by the United States, but parts of this legislation have been subsequently struck down by the Supreme Court.
Suspension of habeas corpus has occurred in many other countries. In Canada, it was suspended to justify the internment of several thousand foreign nationals, mostly Germans and Ukrainians, during and after World War I and of Japanese Canadians during World War II. It was also briefly suspended in 1970 in response to terrorist acts committed by radical Quebec separatists. It was suspended by order of President Ferdinand Marcos in the Philippines in 1971, followed the next year by a declaration of martial law.