What are Ex Parte Merryman

Ex Parte Merryman is the writ of habeas corpus issued by U.S. Supreme Court Chief Justice Roger B. Taney to John Merryman after the Maryland resident is arrested for raising forces for the Confederacy. It is disobeyed and Taney protests only Congress has the power to suspend the writ. This precipitates the first public discussion of Lincoln's actions, which expand in breadth.