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 Pennsylvania, the primary statute governing driving under the influence of alcohol or controlled substances is found in Title 75 (Vehicle Code) of the Pennsylvania Consolidated Statutes. The state uses the term 'DUI' (Driving Under the Influence) to refer to the offense of operating a vehicle while impaired by alcohol or drugs. Pennsylvania law defines DUI with a tiered approach based on the driver's blood alcohol concentration (BAC) levels, with higher penalties for higher BAC levels. The legal limit for most drivers is a BAC of 0.08%, but lower limits apply to commercial drivers and drivers under the age of 21. Penalties for DUI in Pennsylvania can include fines, license suspension, mandatory education or treatment programs, and even imprisonment, depending on the severity of the offense and the number of prior offenses. Additionally, Pennsylvania has implied consent laws, meaning that drivers are presumed to have consented to chemical testing for BAC, and refusal to submit to testing can result in enhanced penalties. For boating under the influence (BUI), the regulations are set forth in the Pennsylvania Fish and Boat Code, and similar to DUI, it is illegal to operate watercraft while under the influence of alcohol or drugs.