32 U.S.C. § 313
Appointments and enlistments: age limitations
(a)
To be eligible for original enlistment in the National Guard, a person must be at least 17 years of age and under 45, or under 64 years of age and a former member of the Regular Army, Regular Navy, Regular Air Force, or Regular Marine Corps. To be eligible for reenlistment, a person must be under 64 years of age.
(b)
To be eligible for appointment as an officer of the National Guard, a person must—
(1)
be a citizen of the United States; and
(2)
be at least 18 years of age and under 64.
( Aug. 10, 1956, ch. 1041 , 70A Stat. 604 ; Pub. L. 85–861, § 2(9) , Sept. 2, 1958 , 72 Stat. 1544 ; Pub. L. 90–130, § 2(2) , Nov. 8, 1967 , 81 Stat. 383 .)