Ex parte Milligan
Ex parte Milligan, 71 U.S. (4 Wall.) 2 (1866), is a landmark decision of the U.S. Supreme Court that ruled that the use of military tribunals to try civilians when civil courts are operating is unconstitutional. In Ex parte Milligan, the Court was unwilling to uphold former President Abraham Lincoln's assertion of power to use military commissions to try civilian opponents of the war, part of the administration's controversial plan to deal with Union dissenters during the American Civil War.