JM 1-6.620
A Department of Justice employee who is summoned to appear and testify, or who is assigned to present testimony or to identify official documents in connection with a judicial or agency proceeding, is entitled to travel expenses if authorized by the Department of Justice to appear. Expenses are paid in accordance with normal government travel provisions, 5 U.S.C. §§ 5701 to 5708, unless reimbursed by the court or by the party summoning the witness. See 5 U.S.C. § 5751. The appropriate amount chargeable for travel expenses is detailed in 28 C.F.R. § 21.1.
[updated April 2018]