235 ILCS 5/7-10
A copy of the rule, regulation, order or decision of the State commission or the license appeal commission, in any proceeding before it, certified under the seal of said commission, shall be served upon each party of record to the proceeding before the commission and service upon any attorney of record for any such party shall be deemed service upon such party. Each party appearing before said commission shall enter his appearance and indicate to the commission his address for the service of a copy of any rule, regulation, order, decision or notice and the mailing of a copy of any rule, regulation or order of said commission or of any notice by said commission, in said proceeding, to said party at such address shall be deemed service thereof upon such party.
Within 20 days after the service of any rule, regulation, order or decision of said commission upon any party to the proceeding, such party may apply for a rehearing in respect to any matters determined by said commission. If a rehearing is granted, the commission shall hold the rehearing and render a decision within 20 days from the filing of the application for rehearing with the secretary of the commission. The time for holding such rehearing and rendering a decision may be extended for a period not to exceed 30 days, for good cause shown, and by notice in writing to all parties of interest. No action for the judicial review of any decision of said commission shall be allowed unless the party commencing such action has first filed an application for a rehearing and the commission has acted upon said application. Only one rehearing may be granted by the commission on application of any one party.
235 ILCS 5/7-10