32 U.S.C. § 307

(a) To be eligible for Federal recognition as an officer of the National Guard, a person must— (1) receive an appointment with a view to filling a vacancy in a federally recognized unit or organization of the National Guard; (2) have the qualifications prescribed by the Secretary concerned for the grade, branch, position, and type of unit or organization involved; and (3) except as provided in subsections (d) and (e) of this section, pass an examination for physical, moral, and professional fitness to be prescribed by the President, and subscribe to the oath of office prescribed by section 312 of this title . (b) The examination prescribed by subsection (a)— (1) shall be conducted, for the Army National Guard, by a board of three commissioned officers designated by the Secretary of the Army from members of the Regular Army or the Army National Guard of the United States, or both, and for the Air National Guard, by a board of three commissioned officers designated by the Secretary of the Air Force from members of the Regular Air Force or the Air National Guard of the United States, or both; and (2) may be held before original appointment or promotion. (c) If such a board finds a person qualified, the Chief of the National Guard Bureau may issue to him a certificate of eligibility for Federal recognition for the office for which he was found qualified. If he is originally appointed or promoted within two years to that office, he is entitled to Federal recognition without further examination, except as to physical condition. (d) Subject to subsection (a)(1) and (2) and to such physical examination as may be prescribed, Federal recognition shall be extended to each officer of the Army Reserve who has qualified for appointment as an officer of the Army National Guard in his reserve grade. Similarly, Federal recognition shall be extended to each officer of the Air Force Reserve who has qualified for appointment as an officer of the Air National Guard. Federal recognition extended under this subsection is effective from the date of appointment in the Army National Guard or the Air National Guard, as the case may be. (e) Subject to subsection (a)(1) and (2), Federal recognition shall be extended to each officer of the Air Force Reserve who is appointed in a commissioned grade in the Air National Guard to fill a vacancy, if on the date on which he is appointed his reserve grade is the same as the grade in which he is appointed or his name is on a recommended list for promotion to that reserve grade. (f) Federal recognition extended under subsection (d) or (e) is effective from the date of appointment in the Army National Guard or the Air National Guard, as the case may be.