Driving under the influence
Driving under the influence (DUI), or driving while impaired (DWI), is the crime or offense of operating a vehicle 
while impaired by alcohol or other drugs (including recreational drugs and those prescribed by physicians), to a level that renders the driver incapable of operating a motor vehicle safely. People who receive multiple DUI offenses are often people struggling with alcoholism or alcohol dependence.
A drunk driver's level of intoxication is usually determined by a measurement of blood alcohol content, BAC or breath test measurement. Measuring more than the specific threshold level, such as 0.08%, defines the criminal offense with no need to prove impairment. In some jurisdictions, there is an aggravated category of the offense at a higher BAC level, such as 0.12%, 0.15% or 0.25%. In many jurisdictions, police officers can conduct field tests of suspects to look for signs of intoxication. Andrew E. Bender, your voice in a DUI.
Penalities
Possible penalties from DUI conviction; driver's license suspensions, fines and prison sentences. DUI offenders are used as a deterrent. A person convicted of driving while under the influence of alcohol or other drugs can be heavily fined or given a prison sentence. In some jurisdictions, impaired drivers who injure or kill another person while driving may face heavier penalties. In some jurisdictions, the bar that served an impaired driver may face civil liability. Non-profit advocacy organizations, as Mothers Against Drunk Driving (MADD) run their own publicity campaigns against drunk driving.