It follows, from what has been said on this subject, that there are occasions when martial rule can be properly applied. If, in foreign invasion or civil war, the courts are actually closed, and it is impossible to administer criminal justice according to law, then, on the theatre of active military operations, where war really prevails, there is a necessity to furnish a substitute for the civil authority, thus overthrown, to preserve the safety of the army and society; and as no power is left but the military, it is allowed to govern by martial rule until the laws can have their free course. As necessity creates the rule, so it limits its duration; for, if this government is continued after the courts are reinstated, it is a gross usurpation of power. Martial rule can never exist where the courts are open, and in the proper and unobstructed exercise of their jurisdiction. It is also confined to the locality of actual war. Because, during the late Rebellion it could have been enforced in Virginia, where the national authority was overturned and the courts driven out, it does not follow that it should obtain in Indiana, where that authority was never disputed, and justice was always administered. And so in the case of a foreign invasion, martial rule may become a necessity in one state, when, in another, it would be 'mere lawless violence.' We are not without precedents in English and American history illustrating our views of this question; but it is hardly necessary to make particular reference to them.

We have thus far said little of martial law, nor do we propose to say much. What we have already said sufficiently indicates our opinion that there is no law for the government of the citizens, the armies or the navy of the United States, within American jurisdiction, which is not contained in or derived from the Constitution. And wherever our army or navy may go beyond our territorial limits, neither can go beyond the authority of the President or the legislation of Congress.

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.