46 USC 6308 - Information barred in legal proceedings

(a) Notwithstanding any other provision of law, no part of a report of a marine casualty investigation conducted under section 6301 of this title, including findings of fact, opinions, recommendations, deliberations, or conclusions, shall be admissible as evidence or subject to discovery in any civil or administrative proceedings, other than an administrative proceeding initiated by the United States.
(b) Any member or employee of the Coast Guard investigating a marine casualty pursuant to section 6301 of this title shall not be subject to deposition or other discovery, or otherwise testify in such proceedings relevant to a marine casualty investigation, without the permission of the Secretary. The Secretary shall not withhold permission for such employee or member to testify, either orally or upon written questions, on solely factual matters at a time and place and in a manner acceptable to the Secretary if the information is not available elsewhere or is not obtainable by other means.
(c) Nothing in this section prohibits the United States from calling the employee or member as an expert witness to testify on its behalf. Further, nothing in this section prohibits the employee or member from being called as a fact witness in any case in which the United States is a party. If the employee or member is called as an expert or fact witness, the applicable Federal Rules of Civil Procedure govern discovery. If the employee or member is called as a witness, the report of a marine casualty investigation conducted under section 6301 of this title shall not be admissible, as provided in subsections (a) and (b), and shall not be considered the report of an expert under the Federal Rules of Civil Procedure.
(d) The information referred to in subsections (a), (b), and (c) of this section shall not be considered an admission of liability by the United States or by any person referred to in those conclusions and statements.