620 ILCS 5/54
Any party to a proceeding before the Department shall have the right to inspect the records of all investigations, inquiries or hearings conducted by or under the authority of the Department, which may relate to the issues involved in such proceeding and to submit suggestions as to the matters to be investigated or as to questions to be propounded. If the Department is satisfied that such suggested investigation should be made or such suggested questions answered, and that the information desired is within the power of any party to furnish, it shall enter an order requiring an investigation to be made or the questions to be answered, and upon failure or refusal to comply with such order, the Department shall either refuse to grant the relief prayed for by the party refusing to comply or may grant the relief prayed by the opposing party against the party refusing to comply.
620 ILCS 5/54