Pub. L. 90-448, tit. IV, sec. 408
incontestability
incontestability Sec. 408. Any guarantee made by the Secretary under this title shall be conclusive evidence of the eligibility of the obligations for such guarantee, and the validity of any guarantee so made shall lie incontestable in the hands of a qualified holder of the guaranteed obligation except for fraud or material misrepresentation oil the part of such holder.