https://en.wikipedia.org/wiki/Military_tribunals_in_the_United_States

Military tribunals in the United States are military courts designed to try members of enemy forces during wartime, operating outside the scope of conventional criminal and civil proceedings. The judges are military officers and fulfill the role of jurors. Military tribunals are distinct from courts-martial.

A military tribunal is an inquisitorial system based on charges brought by military authorities, prosecuted by a military authority, judged by military officers, and sentenced by military officers against a member of an enemy army.

The United States has made use of military tribunals or commissions, rather than rely on a court-martial, within the military justice system, during times of declared war or rebellion.

Most recently, as discussed below, the administration of George W. Bush sought to use military tribunals to try "unlawful enemy combatants", mostly individuals captured abroad and held at a prison camp at a military base at Guantánamo Bay, Cuba.

A military tribunal or commission is most usually used to refer to a court that asserts jurisdiction over persons who are members of an enemy army, are held in military custody, and are accused of a violation of the laws of war. In contrast, courts-martial generally take jurisdiction over only members of their own military. A military tribunal or commission may still use the rules and procedures of a court-martial, although that is not generally the case.

Military tribunals also, generally speaking, do not assert jurisdiction over people who are acknowledged to be civilians who are alleged to have broken civil or criminal laws. However, military tribunals are sometimes used to try individuals not affiliated with a particular state's military who are nonetheless accused of being combatants and acting in violation of the laws of war.