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 Maryland, DUI (driving under the influence) and DWI (driving while intoxicated) are distinct criminal offenses related to operating a vehicle while impaired by alcohol or drugs. A DUI typically refers to driving with a blood alcohol concentration (BAC) of 0.08% or higher, which is considered per se intoxication. A DWI, on the other hand, may be charged when a person's BAC is between 0.07% and 0.08%, or when there is evidence of impairment that does not meet the per se threshold of 0.08%. Maryland law also recognizes that even with a BAC below 0.07%, a driver may still be charged with DWI if there is sufficient evidence of impairment. Penalties for these offenses can include fines, imprisonment, and the suspension or revocation of the driver's license. Additionally, Maryland has a zero-tolerance policy for underage drinking and driving, meaning that drivers under the age of 21 can face DUI charges with any detectable amount of alcohol in their system.