22 USC 2512 - Experts and consultants

(a) Employment; compensation, travel expenses and per diem; renewal of contracts 
Experts and consultants or organizations thereof may, as authorized by section 3109 of title 5, be employed by the President for the performance of functions under this chapter, and individuals so employed may be compensated at rates not in excess of the per diem equivalent of the highest rate payable under section 5332 of title 5, and while away from their homes or regular places of business, they may be paid actual travel expenses and per diem in lieu of subsistence and other expenses at the applicable rate prescribed in the Standardized Government Travel Regulations, as amended from time to time, while so employed: Provided, That contracts for such employment may be renewed annually.
(b) Exemption from restrictions upon receipt of retirement benefits 
Service of an individual as a member of the Council authorized to be established by section 25111 of this title or as an expert or consultant under subsection (a) of this section shall not be considered as employment or holding of office or position bringing such individual within the provisions of sections 3323(b) and 8344 of title 5, section 4064 of this title, or any other law limiting the reemployment of retired officers or employees or governing the simultaneous receipt of compensation and retired pay or annuities.
[1] See References in Text note below.