29 C.F.R. § 1991.102 – Obligations and prohibited acts.

(a) No employer may discharge, demote, suspend, threaten, harass, or in any other manner retaliate against, including, but not limited to, intimidating, restraining, coercing, blacklisting, or disciplining, a covered individual in the terms and conditions of employment of the covered individual because of any lawful act done by the covered individual to engage in any of the activities specified in paragraph (b)(1) and (2) of this section.
(b) A covered individual is protected against retaliation (as described in paragraph (a) of this section) for any lawful act done by the covered individual:
1. (1) To provide information, or cause information to be provided to the Federal Government or a person with supervisory authority over the individual, or any other person working for the employer who has the authority to investigate, discover, or terminate misconduct, regarding:
  1. (i) Any violation of, or any act or omission the covered individual reasonably believes to be a violation of, the antitrust laws; or
  2. (ii) Any violation of, or any act or omission the covered individual reasonably believes to be a violation of, another criminal law committed in conjunction with a potential violation of the antitrust laws or in conjunction with an investigation by the Department of Justice of a potential violation of the antitrust laws; or
2. (2) To cause to be filed, testify in, participate in, or otherwise assist a Federal Government investigation or a Federal Government proceeding filed or about to be filed (with any knowledge of the employer) relating to:
  1. (i) Any violation of, or any act or omission the covered individual reasonably believes to be a violation of, the antitrust laws; or
  2. (ii) Any violation of, or any act or omission the covered individual reasonably believes to be a violation of, another criminal law committed in conjunction with a potential violation or in conjunction with an investigation by the Department of Justice of a potential violation of the antitrust laws.
3. (3) The term violation with respect to the antitrust laws shall not be construed to include a civil violation of any law that is not also a criminal violation.
4. (4) Paragraphs (b)(1) and (2) of this section shall not apply to any covered individual if the covered individual:
  1. (i) Planned and initiated a violation or attempted violation of the antitrust laws;
  2. (ii) Planned and initiated a violation or attempted violation of another criminal law in conjunction with a violation or attempted violation of the antitrust laws; or
  3. (iii) Planned and initiated an obstruction or attempted obstruction of an investigation by the Department of Justice of a violation of the antitrust laws.