49 C.F.R. § 513.5 – Confidentiality.

(a) In general. Notwithstanding 49 U.S.C. 30167, the Secretary and any officer or employee of the U.S. Department of Transportation shall not disclose any information, including information provided by a whistleblower to the Secretary, that could reasonably be expected to reveal the identity of a whistleblower, except in accordance with the provisions of 5 U.S.C. 552a, unless:
1. (1) Disclosure is required to a defendant or respondent in connection with a public proceeding instituted by the Secretary, the Agency, or any entity described in paragraph (c);
2. (2) The whistleblower provides prior written consent for the information to be disclosed; or
3. (3) The Secretary, or other officer or employee of the U.S. Department of Transportation, receives the information through another source, such as during an inspection or investigation under 49 U.S.C. 30166, and has the authority under other law to release the information.
(b) Use by Attorney General. Notwithstanding paragraph (a) of this section, nothing in this section is intended to limit the ability of the Attorney General to present such evidence to a grand jury or to share such evidence with potential witnesses or defendants in the course of an ongoing criminal investigation.
(c) Availability to Federal Government agencies. Notwithstanding paragraph (a) of this section, without the loss of its status as confidential in the hands of the Administrator, all information referred to in paragraph (a) of this section may, in the discretion of the Administrator, when determined by the Administrator to be necessary or appropriate to accomplish the purposes of 49 U.S.C. Chapter 301, be made available to the U.S. Department of Justice or an appropriate department or agency of the Federal Government, acting within the scope of its jurisdiction, provided that each entity shall maintain information as confidential in accordance with the requirements of paragraph (a).
(d) Redaction. When disclosing any information under paragraph (a) of this section, the Secretary and any officer or employee of the U.S. Department of Transportation shall take reasonable measures not to reveal the identity of the whistleblower by taking measures not to reveal the whistleblower's name, and redacting the whistleblower's name when information is disclosed under paragraph (a).
(e) Section 552(b)(3)(B). The identity of the whistleblower and the information provided to Secretary by the whistleblower shall be considered exempt from disclosure under the provisions of 5 U.S.C. 552 to the fullest extent permitted by law.
(f) The whistleblower. The person should self-identify as a whistleblower at the time the person first submits original information relating to any potential motor vehicle defect, potential noncompliance, or any violation or alleged violation of any notification or reporting requirements under 49 U.S.C. Chapter 301 or a regulation thereunder by submitting a WB-INFO form. If the person is represented by a legal representative, that legal representative should identify the client as a whistleblower at the time the legal representative first submits original information relating to any potential motor vehicle defect, potential noncompliance, or any violation or alleged violation of any notification or reporting requirements under 49 U.S.C. Chapter 301 or regulation thereunder on behalf of the legal representative's client in the WB-INFO form.