No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a Grand Jury, except in cases arising in the land or naval forces, or in the Militia, when in actual service in time of War or public danger; nor shall any person be subject for the same offence to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property, without due process of law; nor shall private property be taken for public use, without just compensation.
The protection of indictment by grand jury extends to all persons except those serving in the armed forces. All persons in the regular armed forces are subject to court martial rather than grand jury indictment or trial by jury.1 The exception’s limiting words
when in actual service in time of war or public danger apply only to members of the militia, not to members of the regular armed forces. In 1969, in O’Callahan v. Parker, the Court held that offenses that are not
service connected may not be punished under military law, but instead must be tried in the civil courts in the jurisdiction where the acts took place.2 In 1987, however, this decision was overruled, with the Court emphasizing the
plain language of Article I, § 8, clause 14,3 and not directly addressing any possible limitation stemming from the language of the Fifth Amendment.4
[T]he requirements of the Constitution are not violated where, as here, a court-martial is convened to try a serviceman who was a member of the armed services at the time of the offense charged.5 Even under the service connection rule, it was held that offenses against the laws of war, whether committed by citizens or by alien enemy belligerents, could be tried by a military commission.6