Drivers under age 21 with any trace of alcohol in their system violate the Illinois Zero Tolerance Law.  If caught, they will lose their driving privileges as well as face serious additional penalties.
Illinois law also can hold a parent liable when a parent allows a minor to drink at the parent’s home, and the minor goes out and gets into a DUI accident, injuring others. For obvious reasons, the penalties for underage drinkers who drive are severe.