Ill. Admin. Code tit. 20, § 1790.410 – Discovery

a) The parties may exchange known documents, including any written statements or expert opinions, before the prehearing conference or as otherwise required by the ALJ under subsection (b)(1); however, general discovery (e.g., depositions, interrogatories, or requests to produce or admit) is not permitted.
b) Disclosure of the following shall be required in accordance with the time periods set forth in this subsection (b) unless otherwise modified by the ALJ in the order issued pursuant to the prehearing conference:
1. 1) Unless otherwise ordered by the ALJ at least 21 days prior to the commencement of the hearing, each party shall provide the other party with a copy of any document and disclose other evidence that the party may offer into evidence, including any statements as defined by Section 1790.120. This subsection (b)(1) does not require any party to provide copies of documents already provided or disclose evidence already disclosed. Each party shall provide newly discovered documents or disclose other evidence to the opposing party as they become known to the party intending to introduce the document or introduce the other evidence.
2. 2) Unless otherwise ordered by the ALJ at least 21 days prior to the commencement of the hearing, each party shall provide the other party with a list containing the name and address of any witness who may be called to testify. Each party shall provide newly discovered witnesses as they become known to the party intending to call the witness.