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 Alaska, DUI (driving under the influence) is the term used for the offense of operating a motor vehicle while impaired by alcohol or drugs. The state follows the per se intoxication standard, where a blood alcohol concentration (BAC) of .08 or higher is considered evidence of intoxication. However, drivers can still be charged with a DUI with a lower BAC if their mental or physical faculties are impaired. Alaska does not use the term DWI (driving while intoxicated) or OWI (operating while intoxicated) as separate offenses; DUI is the overarching term for impaired driving, regardless of the substance causing the impairment. For drivers under the age of 21, Alaska enforces a 'zero tolerance' law, meaning any detectable amount of alcohol can result in DUI charges. Penalties for DUI in Alaska can include fines, imprisonment, license revocation, and mandatory use of an ignition interlock device, with increased severity for repeat offenses or aggravated circumstances.