DUI

Driving under the influence (DUI), driving while intoxicated (DWI), drunken driving, drunk driving, drink driving, operating under the influence, drinking and driving, or impaired driving is the act of driving a motor vehicle with blood levels of alcohol in excess of a legal limit ("Blood Alcohol Content", or "BAC"). Similar regulations cover driving or operating certain types of machinery while affected by drinking alcohol or taking other drugs, including, but not limited to prescription drugs. This is a criminal offense in most countries. Convictions do not necessarily involve actual driving of the vehicle.

In most jurisdictions a measurement such as a blood alcohol content (BAC) in excess of a specific threshold level, such as 0.05% or 0.08% defines the offense, with no need to prove impairment or being under the influence of alcohol. In some jurisdictions, there is an aggravated category of the offense at a higher level e.g. 0.12%. In most countries, anyone who is convicted of injuring or killing someone while under the influence of alcohol or drugs can be heavily fined, as in France, in addition to being given a lengthy prison sentence. Some jobs have their own rules, for example the Federal Railroad Administration has a 0.04% limit for train crew. Some jurisdictions have multiple levels of BAC; for example, the state of California has a 0.08% BAC limit, which is lowered to 0.04% if the operator holds a commercial driver's license. The California BAC limit is 0.01% for those younger than 21 years of age and those on probation for a previous DUI conviction. Some large corporations have their own rules; Union Pacific Railroad has their own BAC limit of 0.02% that, if violated during a random test or a for-cause test — for example, after a traffic accident — can result in termination of employment.

Many states in the U.S. and provinces in Canada have adopted truth in sentencing laws that enforce strict guidelines on sentencing, differing from previous practice where prison time was reduced or suspended after sentencing had been issued. Some jurisdictions have judicial guidelines requiring a mandatory minimum sentence.

The specific criminal offense may be called, depending on the jurisdiction, driving under the influence (DUI), driving under intense influence (DUII), driving while intoxicated (DWI), "operating under the influence" (OUI) operating while intoxicated (OWI), operating a motor vehicle while intoxicated (OMVI), driving under the combined influence of alcohol and/or other drugs, driving under the influence per se or drunk in charge . Many such laws apply also to motorcycling, boating, piloting aircraft, use of motile farm equipment such as tractors and combines, riding horses or driving a horse-drawn vehicle, or bicycling, possibly with different BAC level than driving. In some jurisdictions there are separate charges depending on the vehicle used, such as BWI (bicycling while intoxicated), which may carry a lighter sentence.

In the United States, local law enforcement agencies made 1,467,300 arrests nationwide for driving under the influence of alcohol in 1996, compared to 1.9 million such arrests during the peak year in 1983. In 1997 an estimated 513,200 DWI offenders were in prison or jail, down from 593,000 in 1990 and up from 270,100 in 1986.