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 Connecticut (CT), the state enforces a zero-tolerance policy for underage drinking and driving. This means that any driver under the age of 21 who is found to have a blood alcohol concentration (BAC) of .02 or higher can be charged with Driving Under the Influence (DUI). Connecticut's per se intoxication level for adults is .08 BAC, but for minors, the threshold is much lower due to the zero-tolerance law. If a minor is caught driving with a BAC of .08 or higher, they will face the same DUI charges as an adult. Additionally, if an officer believes a minor is driving while intoxicated, even without a chemical test, the minor can still be charged with DUI based on the officer's observations. The specific statutes detailing these regulations can be found in Connecticut's penal code or criminal code, and the consequences for underage DUI/DWI can include fines, license suspension, and potentially even jail time, depending on the circumstances and any prior offenses.