29 CFR § 1630.12 - Retaliation and coercion.
(a) Retaliation. It is unlawful to discriminate against any individual because that individual has opposed any act or practice made unlawful by this part or because that individual made a charge, testified, assisted, or participated in any manner in an investigation, proceeding, or hearing to enforce any provision contained in this part.
(b) Coercion, interference or intimidation. It is unlawful to coerce, intimidate, threaten, harass or interfere with any individual in the exercise or enjoyment of, or because that individual aided or encouraged any other individual in the exercise of, any right granted or protected by this part.