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 Tennessee, DUI (driving under the influence) is the primary offense used to describe the criminal act of operating a motor vehicle while impaired by alcohol or drugs. Tennessee law sets the per se blood alcohol concentration (BAC) limit at .08 for drivers over the age of 21. For commercial drivers, the limit is .04, and for drivers under the age of 21, the state has a zero-tolerance policy with a BAC limit of .02. A DUI charge in Tennessee can result from impairment due to alcohol, illegal drugs, prescription medication, or any other substance that impairs a driver's ability to safely operate a vehicle. The state does not use the term DWI (driving while intoxicated) or OWI (operating while intoxicated) as separate offenses; DUI is the encompassing term for impaired driving offenses. Penalties for DUI in Tennessee can include fines, jail time, license suspension, mandatory drug and alcohol education programs, and the installation of an ignition interlock device. Enhanced penalties may apply for higher BAC levels, repeat offenses, or if aggravating factors are present, such as having a minor in the vehicle.