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 New Hampshire (NH), DUI (Driving Under the Influence) and DWI (Driving While Intoxicated) are terms that are used interchangeably to refer to the offense of operating a vehicle while impaired by alcohol or drugs. The state follows the per se intoxication standard, where a driver with a Blood Alcohol Concentration (BAC) of .08 or higher is considered intoxicated by law. However, a driver can still be charged with DUI/DWI in New Hampshire even if their BAC is below .08 if they are found to be impaired to a degree that hinders their ability to drive safely. This includes impairment from prescription medications, over-the-counter drugs, or any other substance that affects mental or physical faculties. For drivers under the age of 21, New Hampshire enforces a 'zero tolerance' law, which means that any detectable amount of alcohol can lead to a DUI charge, with lower BAC thresholds than for those of legal drinking age. Penalties for DUI/DWI in New Hampshire can include fines, license suspension, and even imprisonment, with increased severity for repeat offenses or aggravating factors such as high BAC levels or causing harm to others.