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 South Carolina, the terms DUI (driving under the influence) and DWI (driving while intoxicated) are generally considered to refer to the same offense, which is operating a motor vehicle while under the influence of alcohol or drugs to the extent that one's faculties to drive are materially and appreciably impaired. South Carolina law sets the per se blood alcohol concentration (BAC) limit at 0.08% for drivers 21 years and older, which means that a driver with a BAC at or above this level is considered intoxicated by definition. For drivers under the age of 21, the state has a zero-tolerance policy, and any detectable amount of alcohol can lead to a DUI charge. The state does not use the term OWI (operating while intoxicated). Penalties for DUI in South Carolina can include fines, imprisonment, license suspension, and mandatory participation in alcohol and drug safety programs. The severity of the punishment typically increases with higher BAC levels and with subsequent offenses.