A writ of habeas corpus is a legal order for an inquiry to determine whether a person has been lawfully imprisoned. The U.S. Constitution declares that 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.” President Lincoln ordered the suspension of habeas corpus in parts of Maryland in 1861, following the start of the Civil War. Shortly thereafter, Roger B. Taney, Chief Justice of the United States Supreme Court but sitting as a circuit judge, decided in the case Ex Parte Merryman that the right to suspend habeas corpus lay with Congress, not the president.
Roger B. Taney, ca. 1855. Prints and Photographs Division, Library of Congress.