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 Wisconsin, the state enforces a strict zero-tolerance policy for underage drinking and driving. The law stipulates that any driver under the age of 21 who is found to have a blood alcohol concentration (BAC) of more than 0.0 but less than 0.08 can be charged with an underage Operating While Intoxicated (OWI) offense, which is Wisconsin's equivalent to DUI/DWI. This is in accordance with Wisconsin Statute 346.63(2m). For those under the legal drinking age, a BAC of 0.02 or higher is enough to face penalties. If an underage driver has a BAC of 0.08 or higher, they can be charged with the standard OWI offense, just like an adult. The consequences for underage OWI can include fines, license suspension, and participation in an alcohol education program. It's important to note that Wisconsin may also impose penalties based on an officer's observations and evidence of impairment, even without a chemical test, under its 'Not a Drop' law.