The Judge Advocate General's Corps (JAG or JAG Corps) is the military justice branch or specialty of the United States Air Force, Army, Coast Guard, Marine Corps, and Navy, responsible for providing legal services to the armed forces.

Officers serving in the JAG Corps are typically called judge advocates and serve as legal advisors to their command, handling areas such as administrative law, government contracting, civilian and military personnel law, the law of war, international relations, and environmental law.

They also serve as prosecutors and defense counsel in courts-martial, which are the military's forums for trying criminal cases.