10 U.S.C. § 772: When wearing by persons not on active duty authorized

A member of the Army National Guard or the Air National Guard may wear the uniform prescribed for the Army National Guard or the Air National Guard, as the case may be. A member of the Naval Militia may wear the uniform prescribed for the Naval Militia. A retired officer of the Army, Navy, Air Force, Marine Corps, or Space Force may bear the title and wear the uniform of his retired grade. A person who is discharged honorably or under honorable conditions from the Army, Navy, Air Force, Marine Corps, or Space Force may wear his uniform while going from the place of discharge to his home, within three months after his discharge. A person not on active duty who served honorably in time of war in the Army, Navy, Air Force, Marine Corps, or Space Force may bear the title, and, when authorized by regulations prescribed by the President, wear the uniform, of the highest grade held by him during that war. While portraying a member of the Army, Navy, Air Force, Marine Corps, or Space Force, an actor in a theatrical or motion-picture production may wear the uniform of that armed force if the portrayal does not tend to discredit that armed force. An officer or resident of a veterans’ home administered by the Department of Veterans Affairs may wear such uniform as the Secretary of the military department concerned may prescribe. While attending a course of military instruction conducted by the Army, Navy, Air Force, Marine Corps, or Space Force, a civilian may wear the uniform prescribed by that armed force if the wear of such uniform is specifically authorized under regulations prescribed by the Secretary of the military department concerned. Under such regulations as the Secretary of the Air Force may prescribe, a citizen of a foreign country who graduates from an Air Force or Space Force school may wear the appropriate aviation or space badges of the Air Force or Space Force. Members of the Boy Scouts of America. Members of any other organization designated by the Secretary of a military department.