Ex Parte Milligan

Ex Parte Milligan, U.S. Supreme Court ruling (1866) that civilians may not be tried in military courts except in the immediate area of a theater of war. The ruling overturned the 1864 conviction of Lambdin P. Milligan by an Indiana military court on charges of aiding the Confederacy. The Supreme Court generalized the ruling to protect civilians from military power, stating that the president and Congress do not have the authority to set up military courts for civilian trials where civilian courts are still functioning, thus setting an important civil liberties precedent.