49 C.F.R. § 604.39 – Depositions.

(a) For good cause shown, the PO may order that the testimony of a witness may be taken by deposition and that the witness produce documentary evidence in connection with such testimony. Generally, an order to take the deposition of a witness is entered only if:
1. (1) The person whose deposition is to be taken would be unavailable at the hearing;
2. (2) The deposition is deemed necessary to perpetuate the testimony of the witness; or
3. (3) The taking of the deposition is necessary to prevent undue and excessive expense to a party and will not result in undue burden to other parties or in undue delay.
(b) Any party to the hearing desiring to take the deposition of a witness according to the terms set out in this subpart, shall file a motion with the PO, with a copy of the motion served on each party. The motion shall include:
1. (1) The name and residence of the witness;
2. (2) The time and place for the taking of the proposed deposition;
3. (3) The reasons why such deposition should be taken; and
4. (4) A general description of the matters concerning which the witness will be asked to testify.
(c) If good cause is shown in the motion, the PO in his or her discretion may issue an order authorizing the deposition and specifying the name of the witness to be deposed, the location and time of the deposition, and the general scope and subject matter of the testimony to be taken.
(d) Witnesses whose testimony is taken by deposition shall be sworn or shall affirm before any questions are put to them. Each question propounded shall be recorded and the answers of the witness transcribed verbatim. The written transcript shall be subscribed by the witness, unless the parties by stipulation waive the signing, or the witness is ill, cannot be found, or refuses to sign. The reporter shall note the reason for failure to sign.