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 Colorado, the terms DUI (Driving Under the Influence) and DWAI (Driving While Ability Impaired) are used to describe offenses related to operating a vehicle while under the influence of alcohol or drugs. A DUI is charged when a person operates a vehicle with a Blood Alcohol Concentration (BAC) of 0.08% or higher, which is considered per se intoxication. However, Colorado also recognizes a lesser charge, DWAI, when a person's BAC is between 0.05% and 0.08%, indicating that the driver's abilities are impaired to the slightest degree by alcohol or drugs. For drivers under the age of 21, Colorado enforces a 'zero tolerance' law, which means any detectable amount of alcohol can lead to a DUI charge, often referred to as an Underage Drinking and Driving (UDD) offense. Penalties for DUI and DWAI in Colorado can include fines, jail time, community service, and mandatory alcohol education programs, with increased severity for repeat offenders or cases involving aggravating factors.