29 U.S.C. § 2002: Prohibitions on lie detector use

directly or indirectly, to require, request, suggest, or cause any employee or prospective employee to take or submit to any lie detector test; to use, accept, refer to, or inquire concerning the results of any lie detector test of any employee or prospective employee; any employee or prospective employee who refuses, declines, or fails to take or submit to any lie detector test, or any employee or prospective employee on the basis of the results of any lie detector test; or such employee or prospective employee has filed any complaint or instituted or caused to be instituted any proceeding under or related to this chapter, such employee or prospective employee has testified or is about to testify in any such proceeding, or of the exercise by such employee or prospective employee, on behalf of such employee or another person, of any right afforded by this chapter.