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 Montana (MT), the offense of operating a vehicle while under the influence of alcohol or drugs is commonly referred to as Driving Under the Influence (DUI). Montana Code Annotated (MCA) 61-8-401 et seq. outlines the state's DUI laws. These laws prohibit operating a motor vehicle on public roads if the driver's blood alcohol concentration (BAC) is 0.08% or higher, or if they are under the influence of alcohol, drugs, or a combination of both to a degree that renders them incapable of safely driving. The term 'vehicle' includes motorized, electric, or otherwise-powered transportation devices. Penalties for DUI in Montana can include fines, license suspension, and imprisonment, with increased severity for repeat offenses or high BAC levels. Additionally, Montana has Boating Under the Influence (BUI) laws, which apply to operating watercraft while intoxicated, as per MCA 23-2-523. These laws are designed to ensure safety on both roadways and waterways by deterring impaired operation of vehicles and vessels.