Most states have a zero-tolerance (or near zero-tolerance) blood alcohol concentration (BAC) level of .02 for drivers under the legal drinking age (usually 21) that will result in a DUI/DWI charge. Some states set the BAC level at which a minor may be charged with DUI/DWI at .05. And some states will charge a minor driving a vehicle with a BAC of less than the state’s per se intoxication level (usually .08) with violating a zero-tolerance law such as driving while ability impaired (DWAI)—but will charge a minor with a BAC of .08 or more with per se (pronounced purr-say) DUI/DWI based on the state’s BAC-level definition of intoxication—or, in the absence of a chemical test of blood, breath, or urine, will charge the minor with common law DUI/DWI based on the police officer’s belief the minor was driving while intoxicated.

DUI/DWI criminal offenses, punishments, and terms used for underage DUI/DWI vary from state to state. These laws are generally located in a state’s statutes—often in the penal code or criminal code.

In Illinois, the state enforces a zero-tolerance policy for underage drinking and driving. Drivers under the age of 21 found to have any trace of alcohol in their system will face DUI charges. Specifically, Illinois law sets the BAC limit at .00 for drivers under the legal drinking age of 21. If an underage driver is caught with a BAC between .00 and .08, they can still be charged under the zero-tolerance law. However, if the BAC is .08 or higher, or if there is other evidence of impairment, the underage driver can be charged with a standard DUI, which carries more severe penalties. The consequences for underage DUI/DWI can include license suspension, fines, and possible jail time, among other penalties. It's important to note that even without a chemical test, a minor can be charged with DUI based on an officer's assessment of their impairment.