65 ILCS 5/10-1-18.2

No municipality, including a municipality that is a home rule unit, may regulate the period of time or establish or enforce a statute of limitations relating to charges brought against a police officer before a Police Board, Civil Service Commission, or other board or officer empowered by law or ordinance to investigate police misconduct if the charge is based upon an allegation of the use of unreasonable force by a police officer. The statute of limitations established in Sections 10-1-18 and 10-1-18.1 for those charges are an exclusive exercise of powers and functions by the State under paragraph (h) of Section 6 of Article VII of the Illinois Constitution.