Judge Advocate General's Corps, also known as JAG or JAG Corps, refers to the legal branch or speciality of any of the United States Armed Forces including the Air Force, Army, Coast Guard, Marine Corps, and Navy. Officers serving in the JAG Corps are typically called Judge Advocates. The Marine Corps, Coast Guard and Air Force do not maintain separate JAG Corps per se and judge advocates in those services maintain their line officer-status. In the Army and Navy, JAG officers only serve in legal positions.
Judge Advocates serve primarily as legal advisors to the command to which they are assigned. In this function, they can also serve as the personal legal advisor to their commander. Their advice may cover a wide range of issues dealing with administrative law, government contracting, civilian and military personnel law, law of war and international relations, environmental law, etc. (See below.) They also serve as prosecutors for the military when conducting courts-martial. They are charged with both the defense and prosecution of military law as provided in the Uniform Code of Military Justice. Highly experienced officers of the JAG Corps often serve as military judges in courts-martial and courts of inquiry.