Military Jurisdiction Law and Legal Definition

Military jurisdiction is the power and authority of a threefold character.

There are under the Constitution three kinds of military jurisdiction: one to be exercised both in peace and war; another to be exercised in time of foreign war without the boundaries of the United States, or in time of rebellion and civil war within states or districts occupied by rebels treated as belligerents; and a third to be exercised in time of invasion or insurrection within the limits of the United States, or during rebellion within the limits of states maintaining adhesion to the National Government, when the public danger requires its exercise. The first of these may be called jurisdiction under MILITARY LAW, and is found in acts of Congress prescribing rules and articles of war, or otherwise providing for the government of the national forces; the second may be distinguished as MILITARY GOVERNMENT, superseding, as far as may be deemed expedient, the local law, and exercised by the military commander under the direction of the President, with the express or implied sanction of Congress; while the third may be denominated MARTIAL LAW PROPER, and is called into action by Congress, or temporarily, when the action of Congress cannot be invited, and in the case of justifying or excusing peril, by the President, in times of insurrection or invasion, or of civil or foreign war, within districts or localities where ordinary law no longer adequately secures public safety and private rights. [Ex parte Milligan, 71 U.S. 2, 142 (U.S. 1866)].