Illinois is more vague with their DUI convictions that most states, but that doesn’t mean that it’s more lenient. Illinois has laws, such as enhanced penalties for higher BAC and  drivers with children passengers, that make standardize some punishments for DUIs. A driver can be arrested for a DUI if they are operating a vehicle above their legal limit set for that state. The legal limit in Illinois is as follows: Standard, non-commercial drivers: 0.08% BAC Commercial drivers: 0.04% BAC Drivers under 21: 0% BAC