The Illinois high-BAC enhancement applies when the driver's BAC is 0.16 or higher at the time of testing. On a first-offense DUI, the enhancement adds a mandatory minimum $500 fine and a mandatory minimum 100 hours of community service under 625 ILCS 5/11-501(c)(3). On a second offense, the enhancement adds a mandatory minimum $1,250 fine and mandatory minimum 2 days of imprisonment. On a third offense, mandatory minimum jail rises to 90 days and the fine to $2,500. The enhancement is triggered by the number itself, not by whether the driver appeared unusually impaired. Blood, breath, or urine tests all count for enhancement purposes. Testing chain-of-custody and calibration challenges become critical when BAC is near the threshold.
