The outbreak of the Civil War on April 12, 1861, created a major civil liberties crisis. Although President Abraham Lincoln never formally declared war, he used his authority as commander in chief to expand the powers of the presidency. Even before Congress convened on July 4, Lincoln called for volunteers, spent money unauthorized by Congress, ordered a blockade of Southern ports, and violated civil liberties guaranteed in the Constitution.

All the civil liberties guaranteed by the Bill of Rights and other sections in the Constitution rested on the protection found in Article 1, Section 9: "The privilege of the writ of habeas corpus shall not be suspended, unless in cases of rebellion or invasion the public safety may require it." Known from English history and widely revered as the Great Writ, the writ of habeas corpus ad subjicienolum is a court order directing that a detained individual...