820 ILCS 405/1003
The deposition of any witness residing within or without the State may be taken at the instance of any claims adjudicator, Referee, member of the Board of Review, field auditor, Director's representative, or any of the parties to any proceeding arising under the provisions of this Act in the manner prescribed by law for the taking of like depositions in civil cases in the courts of this State. The Director may, at the request of any such person, issue a dedimus potestatem or commission under the seal of the Department of Employment Security in the same manner as the proper clerk's office is authorized to issue such dedimus potestatem or commission under the seal of the court in connection with any matter pending in the circuit courts of this State.
820 ILCS 405/1003