Section I : Martial law -- Military jurisdiction -- Military necessity -- Retaliation - Art. 13.
Art. 13. Military jurisdiction is of two kinds: First, that which is conferred and defined by statute; second, that which is derived from the common law of war. Military offenses under the statute law must be tried in the manner therein directed; but military offenses which do not come within the statute must be tried and punished under the common law of war. The character of the courts which exercise these jurisdictions depends upon the local laws of each particular country.
In the armies of the United States the first is exercised by courts-martial, while cases which do not come within the "Rules and Articles of War," or the jurisdiction conferred by statute on courts-martial, are tried by military commissions.