Driving under the influence of alcohol (driving while intoxicated, drunk driving, drinking and driving, drink-driving) or other drugs, is the act of operating a motor vehicle (and even a bicycle, boat or horse in some jurisdictions) after having consumed alcohol, to the degree that mental and motor skills are impaired. It is a crime or offence in most countries around the world. Driving under the influence of alcohol legally is known as Buzz Driving. Anti-drunk-driving advertising campaigns In most international jurisdictions, anyone who is convicted of injuring or killing someone while under the influence of alcohol or drugs can be heavily fined. The specific criminal offense may be called, depending on the jurisdiction, driving while intoxicated (DWI), operating while intoxicated (OWI), operating a motor vehicle while intoxicated (OMVI), driving under the influence [of alcohol or other drugs] (DUI), driving under the combined influence of alcohol and/or other drugs, driving under the influence per se or drunk in charge [of a vehicle]. Historically, guilt was established by observed driving symptoms, such as weaving; administering field sobriety tests, such as a walking a straight line heel-to-toe or standing on one leg for 30 seconds; and the arresting officer's subjective opinion of impairment. Starting with the introduction in Norway in 1936 of the world’s first per se law which made it an offense to drive with more than a specified amount of alcohol in the body, objective chemical tests have gradually supplemented the earlier purely judgmental ones. Limits for chemical tests are specific for blood alcohol concentration or concentration of alcohol in breath. With the advent of a scientific test for blood alcohol content (BAC), enforcement regimes moved to pinning culpability for the offense to strict liability based on driving while having more than a prescribed amount of blood alcohol, although this does not preclude the simutaneous existence of the older subjective tests. BAC is most conveniently measured as a simple percent of alcohol in the blood by weight. It does not depend on any units of measurement. In Europe it is usually expressed as milligrams of alcohol per 100 millilitres of blood. However, 100 milliliters of blood weighs essentially the same as 100 milliliters of water, which weighs precisely 100 grams. Thus, for all practical purposes, this is the same as the simple dimensionless BAC measured as a percent. Since 2002 it has been illegal in all 50 US states to drive with a BAC that is 0.08% or higher. The validity of the testing equipment/methods and mathematical relationships for the measurement of breath and blood alcohol have been criticized. Driving while consuming alcohol may be illegal within a jurisdiction. In some it is illegal for an open container of an alcoholic beverage to be in the passenger compartment of a motor vehicle or in some specific area of that compartment. The German model serves to reduce the number of accidents by identifying unfit drivers and removing them from traffic until their fitness to drive has been established again. The Medical Psychological Assessment (MPA) works for a prognosis of the fitness for drive in future, has an interdisciplinary basic approach and offers the chance of individual rehabilitation to the offender. A breathalyzer is a device for estimating blood alcohol content (BAC) from a breath sample. "Breathalyzer" is the brand name of a series of models made by one manufacturer of these instruments (originally Smith and Wesson, later it was sold to National Draeger), but has become a genericized trademark for all such instruments. In Canada, a preliminary non-evidentiary screening device can be approved by Parliament as an approved screening device and an evidentiary breath instrument can be similarly designated as an approved instrument. The U.S. National Highway Traffic Safety Administration maintains a "Conforming Products List" of breath alcohol devices approved for evidentiary use, as well as for preliminary screening use.
