42 USC 216 - Regulations

(a) Prescription by President: appointments, retirement, etc. 
The President shall from time to time prescribe regulations with respect to the appointment, promotion, retirement, termination of commission, titles, pay, uniforms, allowances (including increased allowances for foreign service), and discipline of the commissioned corps of the Service.
(b) Promulgation by Surgeon General; administration of Service 
The Surgeon General, with the approval of the Secretary, unless specifically otherwise provided, shall promulgate all other regulations necessary to the administration of the Service, including regulations with respect to uniforms for employees, and regulations with respect to the custody, use, and preservation of the records, papers, and property of the Service.
(c) Preference to school of medicine 
No regulation relating to qualifications for appointment of medical officers or employees shall give preference to any school of medicine.