19 CFR § 201.5 - Attendance fees and mileage.
(a) Deponents and witnesses. Any person compelled to appear in person to depose or testify in response to a subpoena shall be paid the same fees and mileage as are paid witnesses in the courts of the United States: Provided, that salaried employees of the United States summoned to depose or testify as to matters related to their public employment, irrespective of at whose instance they are summoned, shall be paid in accordance with applicable Government regulations.
(b) Responsibility. The fees and mileage referred to in this section shall be paid by the party at whose instance deponents or witnesses appear: Provided, that when it is the Commission, one or more Commissioners, or one of its employees at whose instance deponents or witnesses appear, such fees and mileage shall be paid by the Commission.