49 CFR § 835.9
Procedure in the event of a subpoena in civil litigation
November 18, 2020
(a) If the Board employee has received a subpoena to appear and testify in connection with civil litigation, a request for his deposition shall not be approved until the subpoena has been withdrawn.
(b) Upon receipt of a subpoena, the employee shall immediately notify the General Counsel and provide all information requested by the General Counsel.
(c) The General Counsel shall determine the course of action to be taken and will so advise the employee.
[63 FR 71608, Dec. 29, 1998]