225 ILCS 316/100

(a) The Department has the power to subpoena and bring before it any person and to take testimony either orally, by deposition, or both, with the same fees and mileage and in the same manner as prescribed in civil cases in circuit courts of this State. (b) The Secretary and the designated hearing officer have the power to administer oaths to witnesses at any hearing which the Department is authorized to conduct, and any other oaths authorized in any Act administered by the Department.