Driving under the influence (DUI) is the offense of driving, operating, or being in control of a vehicle while impaired by alcohol or drugs (including recreational drugs and those prescribed by physicians), to a level that renders the driver incapable of operating a motor vehicle safely. Multiple other terms are used for the offense in various jurisdictions.
Terminology
The name of the offense varies from jurisdiction to jurisdiction and from legal to colloquial terminology. In various jurisdictions the offense is termed driving while impaired, impaired driving, driving while intoxicated (DWI), drunk driving, operating while intoxicated (OWI), operating under the influence (OUI), operating [a] vehicle under the influence (OVI), and drink-driving (UK/Ireland).
In the United States, the specific criminal offense is usually called driving under the influence, but states may use other names for the offense including "driving while intoxicated" (DWI), "operating while impaired" (OWI) or "operating while ability impaired", and "operating a vehicle under the influence" (OVI). Such laws may also apply to boating or piloting aircraft. Vehicles can include farm machinery and horse-drawn carriages, along with bicycles. Other commonly used terms to describe these offenses include drinking and driving, drunk driving, drunken driving, impaired driving, operating under the influence, or "over the prescribed limit".
In the United Kingdom, there are two separate offences to do with alcohol and driving. The first is "Driving or attempting to drive with excess alcohol" (legal code DR10), the other is known as "In charge of a vehicle with excess alcohol" (legal code DR40) or "drunk in charge" due to the wording of the Licensing Act 1872. In relation to motor vehicles, the Road Safety Act 1967 created a narrower offense of driving (or being in charge of) a vehicle while having breath, blood, or urine alcohol levels above the prescribed limits (colloquially called "being over the limit"); and a broader offense of "driving while unfit through drink or drugs," (DR20 and DR80 respectively) which can apply even with levels below the limits. These provisions were re-enacted in the Road Traffic Act 1988. A separate offense in the 1988 Act applies to bicycles. While the 1872 Act is mostly superseded, the offense of being "drunk while in charge ... of any carriage, horse, cattle, or steam engine" is still in force; "carriage" has sometimes been interpreted as including mobility scooters.
Definition
The criminal offense may not involve actual driving of the vehicle, but rather may broadly include being physically "in control" of a car while intoxicated, even if the person charged is not in the act of driving. For example, individuals found in the driver's seat of a car while intoxicated and holding the car keys, even while parked, may be charged with DUI in the majority of U.S. states because they are in control of the vehicle.
In construing the terms DUI, DWI, OWI, and OVI, a few states[which?] such as California therefore make it illegal to drive a motor vehicle while under the influence or driving while intoxicated while the others all indicate that it is illegal to operate a motor vehicle while under the influence. Virtually all of the states permit enforcement of DUI/DWI and OWI/OVI statutes based on "operation and control" of a vehicle, while California and a few others[which?] require actual "driving". "The distinction between these two terms is material, for it is generally held that the word 'drive,' as used in statutes of this kind, usually denotes movement of the vehicle in some direction, whereas the word 'operate' has a broader meaning so as to include not only the motion of the vehicle but also acts which engage the machinery of the vehicle that, alone or in sequence, will set in motion the motive power of the vehicle." (State v. Graves (1977) 269 S.C. 356 [237 S.E.2d 584, 586–588, 586. fn. 8].)
Merriam Webster's Dictionary defines DUI (in the United States) as "1. the act or crime of driving a vehicle while affected by alcohol or drugs; 2. an arrest or conviction for driving under the influence; 3. a person who is arrested for or convicted of driving under the influence."
In some countries (including Australia and many jurisdictions throughout the United States), a person can be charged with a criminal offense for riding a bicycle, skateboard, or horse while intoxicated or under the influence of alcohol.