A person may not seek to have an H-2A worker, a worker in corresponding employment, or a U.S. worker improperly rejected for employment or improperly laid off or displaced waive any rights conferred under 8 U.S.C. 1188, 20 CFR part 655, subpart B, or the regulations in these parts. Any agreement by an employee purporting to waive or modify any rights given to said person under these provisions shall be void as contrary to public policy except as follows:
(a) Waivers or modifications of rights or obligations hereunder in favor of the Secretary shall be valid for purposes of enforcement; and
(b) Agreements in settlement of private litigation are permitted.