Shortly after the start of the American Civil War in 1861, President of the United States Abraham Lincoln took two steps intended to maintain order and public safety in the now-divided country. In his capacity as commander in chief, Lincoln declared martial law in all states and ordered the suspension of the constitutionally protected right to writs of habeas corpus in the state of Maryland and parts of the Midwestern states.

In taking this action, Lincoln was responding to the arrest of Maryland secessionist John Merryman by Union troops. U.S. Supreme Court Chief Justice Roger B. Taney of Maryland had recently issued a writ of habeas corpus demanding that the U.S. Military bring Merryman before the Supreme Court for a hearing. Lincoln’s proclamation effectively blocked Justice Taney’s order from being carried out.

Lincoln’s action did not go unopposed. On May 27, 1861, Chief Justice Taney issued his famous Ex parte Merryman opinion challenging the authority of President Lincoln and the U.S. military to suspend the right to a writ of habeas corpus. Referring to Article I, Section 9, of the Constitution, which allows suspension of habeas corpus “when in cases of rebellion or invasion the public safety may require it,” Taney argued that only Congress—not the president—had the power to suspend habeas corpus.

An 1864 political cartoon entitled, "The Grave of the Union" decrying the suspension of Habeas Corpus during the Civil War. Library of Congress/Corbis/Getty Images

In July 1861, Lincoln sent a message to Congress in which he justified his action, and went on to ignore Taney’s opinion, allowing the suspension of habeas corpus to continue throughout the remainder of the Civil War. Though John Merryman was eventually released, the constitutional question of whether the right to suspend habeas corpus belongs to Congress or the president has never been officially resolved.

On Sept. 24, 1862, President Lincoln issued the following proclamation suspending the right to writs of habeas corpus nationwide:

By the President of the United States of America

A Proclamation

Whereas, it has become necessary to call into service not only volunteers but also portions of the militia of the States by draft in order to suppress the insurrection existing in the United States, and disloyal persons are not adequately restrained by the ordinary processes of law from hindering this measure and from giving aid and comfort in various ways to the insurrection;

Now, therefore, be it ordered, first, that during the existing insurrection and as a necessary measure for suppressing the same, all Rebels and Insurgents, their aiders and abettors within the United States, and all persons discouraging volunteer enlistments, resisting militia drafts, or guilty of any disloyal practice, affording aid and comfort to Rebels against the authority of United States, shall be subject to martial law and liable to trial and punishment by Courts Martial or Military Commission:

Second. That the Writ of Habeas Corpus is suspended in respect to all persons arrested, or who are now, or hereafter during the rebellion shall be, imprisoned in any fort, camp, arsenal, military prison, or other place of confinement by any military authority of by the sentence of any Court Martial or Military Commission.

In witness whereof, I have hereunto set my hand, and caused the seal of the United States to be affixed.

Done at the City of Washington this twenty fourth day of September, in the year of our Lord one thousand eight hundred and sixty-two, and of the Independence of the United States the 87th.

Abraham Lincoln

By the President:

William H. Seward, Secretary of State.

What is a Writ of Habeas Corpus?

Protesters stand during a Senate Judiciary Committee hearing on proposals to limit Guantanamo detainees' access to habeas corpus review. Mark Wilson/Getty Images

Meaning “produce the body,” a writ of habeas corpus is a court order issued by a court of law to a law enforcement agency, jail, or prison holding a person in custody. The order requires the law enforcement agency to turn the named prisoner over to the court so that a judge can determine whether the prisoner had been jailed legally according to due process of law and, if not, whether they should be set free.

A habeas corpus petition is a petition filed with a court by a person who objects to his own or another's detention or imprisonment. The petition must show that the court ordering the detention or imprisonment made a legal or factual error. The right of habeas corpus is the constitutionally bestowed right of a person to present evidence before a court that he or she has been wrongly imprisoned.