49 C.F.R. § 835.5

(a) Testimony of Board employees with unique, firsthand information may be made available for use in civil actions or civil suits for damages arising out of accidents through depositions or written interrogatories. Board employees are not permitted to appear and testify in court in such actions.

(b) Normally, depositions will be taken and interrogatories answered at the Board's office to which the employee is assigned, and at a time arranged with the employee reasonably fixed to avoid substantial interference with the performance of his duties.

(c) Board employees are authorized to testify only once in connection with any investigation they have made of an accident. Consequently, when more than one civil lawsuit arises as a result of an accident, it shall be the duty of counsel seeking the employee's deposition to ascertain the identity of all parties to the multiple lawsuits and their counsel, and to advise them of the fact that a deposition has been granted, so that all interested parties may be afforded the opportunity to participate therein.

(d) Upon completion of the deposition of a Board employee, the original of the transcript will be provided the deponent for signature and correction, which the Board does not waive. A copy of the transcript of the testimony and any videotape shall be furnished, at the expense of the party requesting the deposition, to the Board's General Counsel at Washington, DC headquarters for the Board's files.