Scott, Winfield, 1786-1866, Cuartel General del Egercito, Ordenes generales numero 20, Tampico, Mexico, 19 de febrero 1847 (Tampico, Mexico: Imprenta de la calle de la Carniceria, February 19, 1847)
TAMPICO FEBRUARY 19, 1847
General orders. – Number 20.
1st It can be feared that many and grave crimes not foreseen in the act of Congress establishing the rules and articles for the Government of the United States Army, approved on April 10, 10806, can be committed by individuals of those armies or against them in Mexico during the war between the two republics. Those atrocious crimes that, if committed in the United States or in its organized territories, would be precisely judged and severely punished by the Nation’s ordinary or civil courts, are mentioned here.
2.nd Murder, premeditated murder, injuries or mutilation, rape, assaults and malicious beatings; robbery, larceny, desecration of Churches, cemeteries or houses, and religious buildings; and the destruction of public or private property that was not ordered by a superior officer, are crimes of this nature.
4th Yet, the written code, commonly called the rules and articles of war, as mentioned earlier, does not prescribe the punishment for any of these crimes, even when they are committed by individuals in the army against the person or property of other individuals in the army, except in the limited case mentioned in article 9, nor does it contain any stipulations in the case of similar offenses committed by those same individuals against the persons and properties of an enemy country, if we exclude the very partial articles 51, 52, and 55; and the mentioned code is absolutely silent regarding offenses committed by individuals of the enemy country against individuals in the army or their properties, contrary to the laws of war.
6th Consequently, all the offenses enumerated above in the 2nd paragraph, which can be committed in another country, in the army, or by the army or against the army, absolutely need a supplemental code.
7th This unwritten code is Martial Law, an addition to the written military code, which Congress ordered to be observed in the rules and articles of war; it is an unwritten code that all armies are obligated to follow in enemy countries, not only for their own safety, but also to protect the inoffensive inhabitants and their properties within the theater of military operations, from offenses committed against the laws of war.
8th Martial law has been declared because of this supreme necessity; it is a supplemental code for all camps, military points, and hospitals that are occupied by whatever part of the United States forces in Mexico and by all the columns, escorts, convoys, guards, and detachments of the expressed forces, while they are engaged in continuing the present war in and against the aforesaid Republic.
9th Consequently, any crime enumerated in paragraph No. 2 that is committed: first, by any Mexican inhabitant, denizen, or traveler against the person or property of any individual adherent to or dependant on the United States forces; 2nd By any individual adherent to or dependent on said forces against the person or property of any Mexican inhabitant, denizen, or traveler; 3rd By any individual adherent to or dependant on said forces against the person or property of any other individual adherent to or dependent on said forces, will be punctually judged and punished according to the expressed supplemental code.
10th With this objective, all the delinquents in the above-mentioned cases are ordered to be promptly apprehended, imprisoned, and denounced in order to be judged by a military commission that will be named to this effect.
11th All military commissions, due to this order, will be arranged, governed, and limited according to articles 65, 66, and 97 in the expressed rules and articles of war, and procedures of these commissions will be completely recorded in writing, reviewed and examined, rejected or approved, and all sentences will be executed in accordance with the court-martial, thereby preventing any military commission from judging causes that solely pertain to the court-martial; and also preventing any individual of any class from being sentenced by the court-martial to a punishment that does not fit the nature and grade of the offense, as proved by the evidence, and ensuring that it conforms to the established punishments for similar cases, in any of the United States of America.
Mandated by the Major General.
Calle de la Carnicería  Press number 12.