10 U.S.C. § 771: Unauthorized wearing prohibited

Except as otherwise provided by law, no person except a member of the Army, Navy, Air Force, Marine Corps, or Space Force, as the case may be, may wear—(1) the uniform, or a distinctive part of the uniform, of the Army, Navy, Air Force, Marine Corps, or Space Force; or (2) a uniform any part of which is similar to a distinctive part of the uniform of the Army, Navy, Air Force, Marine Corps, or Space Force.