DUI (driving under the influence), DWI (driving while intoxicated), and OWI (operating while intoxicated) are similar criminal offenses that involve the operation of a motor vehicle, electric vehicle, or sometimes an otherwise-powered vehicle—including boats, aircraft, and bicycles—by an operator who is under the influence of or intoxicated by alcohol or drugs. Per se (pronounced purr-say) intoxication is intoxication by definition—as defined in the state’s statutes by blood alcohol concentration (BAC) of .08 or more (.05 in Utah). And even if a person is not per se intoxicated, they may be intoxicated by not having the normal use of their mental or physical faculties (abilities), for example, and may be charged with a criminal offense.

In some contexts the terms DUI and DWI are used interchangeably, with some states using one term and other states using the other term to define what is essentially the same criminal offense. But in some states both criminal charges are available and there is a legal distinction between them.

For example, in some states with both criminal offenses, DUI is the criminal offense of operating a vehicle under the influence of prescription or recreational drugs, and DWI is the offense of operating a vehicle while intoxicated by alcohol. In some states DWI refers to per se intoxication when the driver’s BAC is above the threshold defined by statute—.08 (.05 in Utah)—and DUI is a criminal offense charged when the police officer believes the driver is under the influence of alcohol, despite the driver’s BAC being below the statutory threshold of .08. And in some states DUI is a separate offense for drivers under the legal age of drinking (21) who have some alcohol in their system, but less than a .08 BAC.

These and other similar alcohol-related operating offenses—including aggravated or enhanced forms of these offenses—vary from state to state in their definitions and potential punishments and are generally located in a state’s statutes—often in the penal code or criminal code.

In Washington State, DUI (Driving Under the Influence) is the primary criminal offense used to address the operation of a motor vehicle by an individual who is under the influence of alcohol or drugs. Washington law defines DUI as driving a vehicle when a person has a blood alcohol concentration (BAC) of 0.08% or higher, or is under the influence of or affected by intoxicating liquor, marijuana, or any drug. Washington does not use the term DWI (Driving While Intoxicated) or OWI (Operating While Intoxicated) as separate offenses; DUI encompasses all forms of impaired driving. The state also has a lower BAC limit of 0.02% for drivers under the age of 21, reflecting a zero-tolerance policy for underage drinking and driving. Penalties for DUI in Washington can include fines, license suspension, installation of an ignition interlock device, and imprisonment. The severity of the punishment typically increases with the number of prior offenses and the level of BAC.