Every state prohibits the operation of a vehicle with a blood alcohol concentration (BAC) of .08% or more (.05% or more in Utah) or while under the influence of drugs or alcohol. However, each state also has special impaired driving laws that apply to drivers who are under 21 years of age. The details of state laws differ, but this article outlines some of the basics of how underage DUI laws work and the consequences of violations.
Drivers who are younger than 21 years old are generally prohibited from driving after consuming alcohol. State laws that prohibit underage drink and driving go by different names such as "zero-tolerance," "underage DUI," and "minor DUI." But, in essence, all these laws simply set a BAC limit that's much lower for underage drivers than it is for drivers who are at least 21 years old.
The underage DUI laws of many states—including Washington, South Carolina, and Colorado—prohibit operation with a BAC of .02% or more. But other states have lower limits or prohibit driving with any amount of consumed alcohol for underage drivers. So even if not visibly impaired, a driver who's under 21 years old can be charged with an underage DUI based on BAC.
The existence of underage DUI laws doesn't make an underage driver immune from being charged with a normal DUI. Underage drivers who are legally impaired or have a BAC of .08% or more will likely face standard DUI charges and penalties.
The penalties associated with an underage DUI are typically less severe than those resulting from a standard DUI conviction. Underage DUI convictions often carry fines of about $250 to $1,000 and up to six months of jail. States laws that don't impose possible jail frequently require in-kind community service hours.
An underage DUI will also lead to license suspension. The suspension period typically ranges from 30 days to one year, depending on the state. However, in some states, suspended drivers might be able to obtain a limited license by installing an ignition interlock device.
In many states, underage DUIs are criminal offenses and are prosecuted in criminal court. However, in some states—like Florida and Kansas—an underage DUI isn't a crime but an administrative violation. In these states, penalties like license suspension and substance abuse treatment are handled administratively.