5 ILCS 100/10-45
Except where otherwise expressly provided by law, when in a contested case a majority of the officials of the agency who are to render the final decision has not heard the case or read the record, the decision, if adverse to a party to the proceeding other than the agency, shall not be made until a proposal for decision is served upon the parties and an opportunity is afforded to each party adversely affected to file exceptions and to present a brief and, if the agency so permits, oral argument to the agency officials who are to render the decision. The proposal for decision shall contain a statement of the reasons therefor and of each issue of fact or law necessary to the proposed decision and shall be prepared by the persons who conducted the hearing or one who has read the record.
5 ILCS 100/10-45