Under the Uniform Code of Military Justice there are 12 categories of individuals that are subject to trial by court-martial, including military personnel, whether active, reserve, or retired; members of certain quasi-military organizations (like the public health service); military prisoners, prisoners of war; and, under certain very limited circumstances, civilians working with the military while deployed. It is important to recognize that a number of the Code’s jurisdictional provisions have been substantially modified on constitutional grounds by the Supreme Court of the United States. Consequently, many significant jurisdictional questions require recourse to case law for resolution despite clear statutory provision.

The effect of other code provisions must also be considered in any specific case. Prior to its 1992 amendment, Article 3(a), for example, was construed to prohibit court-martial of a servicemember for an offense committed prior to a break in service unless its terms were satisfied. In addition, a few of the punitive articles, by their express terms, may only be used to punish members of the armed forces.

Ordinarily, and traditionally, personnel belonging to an armed force are tried only by that armed force. However, in some circumstances military law expressly permits the trial of an offender by a convening authority belonging to a different armed force. Should such a trial take place improperly, the error is nonjurisdictional.