Del. Code tit. 26, § 505

The fees and mileage of witnesses required to attend before the Commission shall be computed at the rate allowed to witnesses in the Superior Court, such fees to be paid when the witness is excused from further attendance. The disbursement made in payment of such fees shall be audited and paid in the same manner provided for the payment of expenses of the Commission. No witness subpoenaed at the instance of parties other than the Commission shall be entitled to compensation from the State for attendance or travel unless the Commission certifies that the testimony was material to the matter investigated.