There are various criminal charges for operating a motorized, electric, or otherwise-powered transportation device on public roadways or waterways while under the influence of or intoxicated by drugs or alcohol, as defined by state law. DUI, DWI, OUI, OWI, and BUI—driving under the influence, driving while intoxicated, operating under the influence, operating while intoxicated, and boating under the influence—are some of the common names for such impaired-driving or impaired-operating criminal offenses.

Laws regarding the definitions and names of such alcohol and drug-related driving offenses vary from state to state and are usually located in a state’s statutes—often in the penal code or criminal code.

In Delaware, the primary statute governing driving under the influence (DUI) of alcohol or drugs is Title 21, Section 4177 of the Delaware Code. This law prohibits operating a motor vehicle when a person has a blood alcohol concentration (BAC) of 0.08% or higher, or when under the influence of alcohol or drugs to a degree which renders the person incapable of driving safely. Delaware law refers to these offenses as DUI rather than DWI (driving while intoxicated), OUI (operating under the influence), or OWI (operating while intoxicated). The state also has laws against boating under the influence (BUI), which are similar to DUI laws and apply to operating watercraft while impaired. Penalties for DUI/BUI in Delaware can include fines, imprisonment, license suspension, and mandatory participation in alcohol education or treatment programs. The severity of the penalties typically increases with subsequent offenses or if aggravating factors are present, such as a high BAC or causing injury or death.