The Photographic History of The Civil War: in ten volumes, Thousands of Scenes Photographed 1861-65, with Text by many Special Authorities, Volume 7: Prisons and Hospitals.
Francis Trevelyan Miller, Ed.

Naturally the prisoners at once sought relief through the writ of habeas corpus and demanded a hearing that they might be permitted to hear the charges against them. The provision of the Constitution of the United States in regard to the right of this writ is as follows, ‘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.’ During the whole period from the adoption of the Constitution until 1861 there seems to be no case ‘in which an American citizen was arrested without warrant, imprisoned without a charge preferred, and released after months and years of incarceration without trial.’ It had been common judgment of Constitutional lawyers that only Congress had the right to suspend this writ, though the necessity for such action had never arisen.

President Lincoln, however, very early had claimed the right to suspend the writ by his own authority. On April 27, 1861, he authorized General Scott to suspend the right anywhere on, or in the vicinity of, the military line between Washington and Philadelphia. The line was extended to New York on July 2d, and to Bangor, Maine, on October 11th. The commanders of prisons were instructed to refuse to allow themselves to be served with writs, and if service had been secured, either to decline to appear, or to appear and courteously refuse to carry out the instruction of the court.

A test case was that of John Merryman, who was arrested on the charge of treason, May 25, 1861. Chief Justice Taney of the United States Supreme Court issued a writ of habeas corpus to which General Cadwalader refused to respond. As no posse could execute the writ by force, Justice Taney ordered a copy sent to the President, who was advised by the attorney-general that he had the power to suspend the writ whenever he deemed it necessary, and that this was a part of the war-powers granted by the Constitution.