29 U.S.C. § 623(d)
Age Discrimination in Employment Act,
(d) Opposition to unlawful practices: participation in investigations, proceedings, or litigation. It shall be unlawful for an employer to discriminate against any of his employees or applicants for employment, for an employment agency to discriminate against any individual, or for a labor organization to discriminate against any member thereof or applicant for membership, because such individual, member or applicant for membership has opposed any practice made unlawful by this section, or because such individual, member or applicant for membership has made a charge, testified, assisted, or participated in any manner in an investigation, proceeding, or litigation under this chapter.
42 U.S.C. § 12203
Americans With Disabilities Act
(a) Retaliation. No person shall discriminate against any individual because such individual has opposed any act or practice made unlawful by this chapter or because such individual made a charge, testified, assisted, or participated in any manner in an investigation, proceeding, or hearing under this chapter.
(b) Interference, coercion, or intimidation. It shall be unlawful to coerce, intimidate, threaten, or interfere with any individual in the exercise or enjoyment of. or on account of his or her having exercised or enjoyed, or on account of his or her having aided or encouraged any other individual in the exercise or enjoyment of. any right granted or protected by this chapter.
(c) Remedies and procedures. The remedies and procedures available under sections 12117. 12133. and 12188 of this title shall be available to aggrieved persons for violations of subsections (a) and (b) of this section, with respect to subchapter I. subchapter II and subchapter III of this chapter, respectively.
20 U.S.C. §4018
Asbestos School Hazard Abatement,
No State or local educational agency receiving assistance under this subchapter may discharge any employee or otherwise discriminate against any employee with respect to the employee&s compensation, terms, conditions, or privileges of employment because the employee has brought to the attention of the public information concerning any asbestos problem in the school buildings within the jurisdiction of such agency.