In Illinois as elsewhere, you cannot be arrested for DUI unless the police have probable cause. Chicago DUI Attorney Sarah Toney shares what you can expect after being arrested for drunk driving.Let us help you navigate this challenging situation with the expertise and dedication you deserve. Posted in: DUI - Drunk Driving. What is a DUI in Illinois? In Illinois, DUIs are traffic offenses under the Illinois Vehicle Code. In Illinois a base level DUI is a class A Misdemeanor offense. However, a driver can also be charged with a felony DUI. All residents of Illinois should understand how the DUI arrest process and aftermath works before ever getting behind the wheel while intoxicated. If you're arrested for drunk driving, you must understand not just punishments come with a DUI conviction, but it can have a long-term effect on your life too.