Pub. L. 84-1028, tit. 10, subtit. B, pt. II, ch. 333, sec. 3261
Army National Guard of United States
§ 3261. Army National Guard of United States (a) Except as provided in subsection (b), to become an enlisted member of the Army National Guard of the United States, a person must— (1) be enlisted in the Army National Guard; (2) subscribe to the oath set forth in section 304 of title 32; and (3) be a member of a federally recognized unit or organization of the Army National Guard in the grade in which he is to be enlisted as a Reserve. (b) A member of the Army Reserve who is enlisted in the Army National Guard in his reserve grade, and is a member of a federally recognized unit or organization thereof, becomes a memeber of the Army National Guard of the United States and ceases to be a member of the Army Reserve.