49 USC 31143 - Investigating complaints and protecting complainants

(a) Investigating Complaints.— 
The Secretary of Transportation shall conduct a timely investigation of a nonfrivolous written complaint alleging that a substantial violation of a regulation prescribed under this subchapter is occurring or has occurred within the prior 60 days. The Secretary shall give the complainant timely notice of the findings of the investigation. The Secretary is not required to conduct separate investigations of duplicative complaints.
(b) Protecting Complainants.— 
Notwithstanding section 552 of title 5, the Secretary may disclose the identity of a complainant only if disclosure is necessary to prosecute a violation. If disclosure becomes necessary, the Secretary shall take every practical means within the Secretarys authority to ensure that the complainant is not subject to harassment, intimidation, disciplinary action, discrimination, or financial loss because of the disclosure.