29 CFR 30.17: Intimidation and retaliation prohibited.

(a) A participant in an apprenticeship program may not be intimidated, threatened, coerced, retaliated against, or discriminated against because the individual has:

(1) Filed a complaint alleging a violation of this part;

(2) Opposed a practice prohibited by the provisions of this part or any other Federal or State equal opportunity law;

(3) Furnished information to, or assisted or participated in any manner, in any investigation, compliance review, proceeding, or hearing under this part or any Federal or State equal opportunity law; or

(4) Otherwise exercised any rights and privileges under the provisions of this part.

(b) Any sponsor that permits such intimidation or retaliation in its apprenticeship program, including by participating employers, and fails to take appropriate steps to prevent such activity will be subject to enforcement action under § 30.15.