10 U.S.C. § 773

(a) A person for whom one of the following uniforms is prescribed may wear it, if it includes distinctive insignia prescribed by the Secretary of the military department concerned to distinguish it from the uniform of the Army, Navy, Air Force, Marine Corps, or Space Force, as the case may be: (1) The uniform prescribed by the university, college, or school for an instructor or member of the organized cadet corps of— (A) a State university or college, or a public high school, having a regular course of military instruction; or (B) an educational institution having a regular course of military instruction, and having a member of the Army, Navy, Air Force, Marine Corps, or Space Force as instructor in military science and tactics. (2) The uniform prescribed by a military society composed of persons discharged honorably or under honorable conditions from the Army, Navy, Air Force, Marine Corps, or Space Force to be worn by a member of that society when authorized by regulations prescribed by the President. (b) A uniform prescribed under subsection (a) may not include insignia of grade the same as, or similar to, those prescribed for officers of the Army, Navy, Air Force, Marine Corps, or Space Force. (c) Under such regulations as the Secretary of the military department concerned may prescribe, any person who is permitted to attend a course of instruction prescribed for members of a reserve officers’ training corps, and who is not a member of that corps, may, while attending that course of instruction, wear the uniform of that corps.