49 CFR § 511.49
Fees
November 18, 2020
(a) Witnesses. Any person compelled to appear in person in response to a subpoena or notice of oral examination shall be paid at least the same attendance and mileage fees as are paid witnesses in the courts of the United States, in accordance with title 28, U.S.C., section 1821.
(b) Responsibility. The fees and mileage referred to in this section shall be paid by the party at whose instance witnesses appear.