Any enlisted member who has completed thirty years’ service may, upon his own application, in the discretion of the Commandant, be retired from active service.
14 U.S. Code § 2305 - Voluntary retirement after thirty years’ service
Said section has been divided. That part dealing with retirement of enlisted men is placed in this section. That part dealing with retirement of commissioned officers is placed in section 231 of this title. That part dealing with retirement of warrant officers is placed in section 304 of this title. That part providing for retired pay is incorporated in section 423 of this title. That part providing for assignment of duties to retired personnel is incorporated in sections 241, 311, and 360 of this title.
The authority to approve was granted to the Commandant in lieu of the Secretary. 81st Congress, House Report No. 557.