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 Massachusetts, the law is strict regarding underage drinking and driving. The state adheres to a zero-tolerance policy for drivers under the age of 21. This means that if an underage driver is found to have a blood alcohol concentration (BAC) of 0.02% or higher, they can be charged with Operating Under the Influence (OUI), which is the term used in Massachusetts instead of DUI/DWI. The 0.02% limit is substantially lower than the standard 0.08% BAC limit for drivers 21 and over. If an underage driver is found with a BAC of 0.08% or higher, they will face the same OUI charges as an adult. Penalties for underage OUI in Massachusetts can include fines, license suspension, and enrollment in alcohol education programs. It's important to note that these penalties can apply even without a chemical test if a police officer has reason to believe the minor was operating a vehicle while impaired.