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 California, the state adheres to a zero-tolerance policy for underage drinking and driving. This means that for drivers under the age of 21, any detectable amount of alcohol in their system can result in a DUI charge. Specifically, California sets the BAC limit at 0.01% for drivers under 21, which is effectively a no-tolerance stance. If an underage driver is found with a BAC of 0.01% or higher, they can be charged with a DUI. For those under 21 with a BAC of 0.05% or higher, additional charges may apply. Furthermore, if an underage driver has a BAC of 0.08% or more, they can be charged with the standard DUI offense that applies to drivers of legal drinking age. California's approach to underage DUI is strict, and the consequences can include license suspension, fines, and mandatory alcohol education programs. The specific statutes detailing these regulations can be found in the California Vehicle Code, sections 23136, 23140, and 23152, among others.