Illinois Statutes Chapter 625. Vehicles § 5/11-208.5. Prosecution of felony DUI by local authorities prohibited

(a) The powers of a local authority to enact or enforce any ordinance or rule with respect to the streets or highways under its jurisdiction relating to driving under the influence of alcohol, other drug or drugs, intoxicating compound or compounds, or any combination thereof is limited to the enactment and enforcement of ordinances or rules the violation of which would constitute a misdemeanor under Section 11-501 of the Illinois Vehicle Code.

(b) A local authority may not enact or enforce any ordinance or rule with respect to streets and highways under its jurisdiction if a violation of that ordinance or rule would constitute a felony under Section 11-501 of the Illinois Vehicle Code. The municipality may, however, charge an offender with a municipal misdemeanor offense if the State's Attorney rejects or denies felony charges for the conduct that comprises the charge.

(c) A municipal attorney who is aware that, based on a driver's history, the driver is subject to prosecution for a felony under Section 11-501 of the Illinois Vehicle Code, must notify the State's Attorney of that county of the driver's conduct and may not prosecute the driver on behalf of the municipality.