Article 1, Section 8, Clause 16
Sir Matthew Hale, History of the Common Law 1713 (posthumous)Gray 26--27
Touching the business of martial law, these things are to be observed, viz.:
First. That in truth and reality it is not a law, but something indulged rather than allowed as a law; the necessity of government, order, and discipline in an army, is that only which can give those laws a countenance: quod enim necessitas cogit defendit.
Secondly. This indulged law was only to extend to members of the army, or to those of the opposed army, and never was so much indulged as intended to be executed or exercised upon others, for others who had not listed under the army had no color or reason to be bound by military constitutions applicable only to the army, whereof they were not parts, but they were to be ordered and governed according to the laws to which they were subject, though it were a time of war.
Thirdly. That the exercises of martial law, whereby any person should lose his life, or member, or liberty, may not be permitted in time of peace, when the king's courts are open for all persons to receive justice according to the laws of the land. This is declared in the Petition of Right (3 Car. I), whereby such commissions and martial law were repealed and declared to be contrary to law.
The Founders' Constitution
Volume 3, Article 1, Section 8, Clause 16, Document 1
The University of Chicago Press
Hale, Sir Matthew. The History of the Common Law of England. Edited by Charles M. Gray. Classics of British Historical Literature. Chicago: University of Chicago Press, 1971.
Easy to print version.