235 ILCS 5/3-11
The principal office of the Commission shall be in Chicago, but the Commission may, with the approval of the Governor, establish and maintain branch offices at other places. The Commission shall hold regular meetings at least once a month at its office, and may hold such special meetings as it may deem necessary at any time and at any place within the State. The Commission may, for authentication of its records, process and proceedings, adopt, keep and use a common seal, of which seal judicial notice shall be taken in all of the courts of the State, and any process, notice or other paper which the Commission may be authorized by law to issue, shall be deemed sufficient if signed by the secretary of said Commission and authenticated by such seal; and all acts, orders, proceedings, rules, regulations, entries, minutes, and other records of said Commission, and all reports and documents filed with said Commission may be proved in any court of this State by copy thereof certified to by the secretary of said Commission with the seal of said Commission attached.
235 ILCS 5/3-11