The writ of habeas corpus ad subjiciendum is one of a number of so-called extraordinary judicial writs, which like those of certiorari, quo warranto, mandamus and injunction are issued by the courts either in order that their commands may be executed, or that a matter may be brought before them for judicial determination. This especial writ, often termed "the writ of liberty," had become one of the established rights of the citizen before the separation of the American colonies from the mother country, and has ever since been regarded by American citizens as the greatest of the safeguards erected by the civil law against arbitrary and illegal imprisonment by whomsoever the detention may be exercised or ordered. Issued as of right (ex 'debito justitice)28 by any court of competent jurisdiction, it orders those to whom it is directed to show good legal justification for holding in custody the person in whose favor it is given. Where such sufficient cause is not shown, an order of release follows as of course.29

26 C. N. Lieber, "The Justification of Martial Law," in the North American Review, 1896.

27 See dissenting opinion of Justice Field and the comments of Hare in his American Constitutional Law, pp. 972 et seq.