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 Iowa, the term 'Operating While Intoxicated' (OWI) is used to describe the criminal offense of operating a motor vehicle while under the influence of alcohol or drugs. Iowa law defines per se intoxication as having a blood alcohol concentration (BAC) of .08 or more. It is important to note that a driver can still be charged with OWI in Iowa even if their BAC is below .08 if they are found to be impaired and unable to operate a vehicle safely. For drivers under the legal drinking age of 21, there is a 'zero tolerance' law, which means that any detectable amount of alcohol can lead to an OWI charge. The state does not use the terms DUI (driving under the influence) or DWI (driving while intoxicated) as separate offenses; OWI is the comprehensive term used for alcohol-related driving offenses. Penalties for OWI in Iowa can include fines, imprisonment, license revocation, and the requirement to complete a substance abuse evaluation and treatment program. Enhanced penalties may apply for higher BAC levels or for repeat offenders.