770 ILCS 23/25
(a) Upon written request by medical authorization signed by the patient or the patient's representative, or by subpoena, any party to a pending court action against whom a claim is asserted for damages resulting from injuries shall be permitted to examine the records of any health care professional or health care provider concerning the health care professional's or health care provider's treatment, care, or maintenance of the injured person. Within 20 days after receiving a written request by medical authorization signed by the patient or the patient's representative, or by subpoena, a health care professional or health care provider claiming a lien under this Act must furnish to the requesting party, or file with the clerk of the court in which the action is pending, all of the following:
(Source: P.A. 93-51, eff. 7-1-03.)