Ex parte Milligan, 4 Wallace (71 U.S.) 2; 18 L. Ed. 281 (1866)
Facts—Milligan, who was not and had never been in the U.S. military, was tried, convicted, and sentenced to be hanged by a military commission established under presidential authority. The president approved the sentence. In a habeas corpus proceeding, Milligan contended the commission had no jurisdiction over him and that he was not accorded a jury trial. The Circuit Court asked the Supreme Court for an opinion.
Question—Did the military tribunal have any legal power and authority to try and to punish Milligan?
Reasons—J. Davis (9–0). Every trial involves the exercise of judicial power. No part of the judicial power of the country was conferred on the military commission because the Constitution expressly vests it “in one supreme court and in such inferior courts as the Congress may from time to time ordain and establish.” The military cannot justify action on the mandate of the president because he is controlled by law, and is duty-bound to execute, not make, the laws. In times of grave emergencies, the Constitution allows the government to make arrests without a writ of habeas corpus, but it goes no further. Martial law can be applied only when there is real necessity, such as during an invasion that would effectually close the courts and civil administration. However, as long as the civil courts are operating, as they were in this case, then the accused is entitled to a civil trial by jury. “The Constitution of the United States is a law for rulers and people, equally in war and in peace, and covers with the shield of its protection all classes of men, at all times, and un- der all circumstances. No doctrine involving more pernicious consequences was ever invented by the wit of men than that any of its provisions can be suspended during any of the great exigencies of government.”
In a concurring opinion, C.J. Chase and three other justices argued that although Congress had not authorized military courts to try civilians in this case, it had the power to do so if it thought the civilian courts were unequal to the task.