225 ILCS 454/25-40
It is declared to be the public policy of this State, pursuant to paragraphs (h) and (i) of Section 6 of Article VII of the Illinois Constitution of 1970, that any power or function set forth in this Act to be exercised by the State is an exclusive State power or function. Such power or function shall not be exercised concurrently, either directly or indirectly, by any unit of local government, including home rule units, except as otherwise provided in this Act. Nothing in this Section shall be construed to affect or impair the validity of Section 11-11.1-1 of the Illinois Municipal Code, as amended, or to deny to the corporate authorities of any municipality the powers granted in the Illinois Municipal Code to enact ordinances prescribing fair housing practices; defining unfair housing practices; establishing Fair Housing or Human Relations Commissions and standards for the operation of these commissions in the administration and enforcement of such ordinances; prohibiting discrimination based on race, color, creed, ancestry, national origin or physical or mental disability in the listing, sale, assignment, exchange, transfer, lease, rental, or financing of real property for the purpose of the residential occupancy thereof; and prescribing penalties for violations of such ordinances.
225 ILCS 454/25-40