Driving Under The Influence - Blood Alcohol Level (BAC)

Blood Alcohol Level (BAC)

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 simultaneous existence of the older subjective tests. BAC is most conveniently measured as a simple percent of alcohol in the blood by weight. Research shows an exponential increase of the relative risk for a crash with a linear increase of BAC as shown in the illustration. BAC does not depend on any units of measurement. In Europe it is usually expressed as milligrams of alcohol per 100 milliliters 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. The per mille (promille) measurement, which is equal to ten times the percentage value, is used in Norway, Sweden and Finland.

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. In some it may be illegal to be asleep in the driver's seat of a vehicle without any intention to drive.

Within the American system, citation for driving under the influence also causes a major spike in car insurance premiums – 94.1% in the first year, and still 63.5% higher by the third year.

The German model serves to reduce the number of accidents by identifying unfit drivers and removing them from 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.

George Smith, a London taxi driver, was the first person to be convicted of drunk driving, on 10 September 1897. He was fined 25 shillings, which is equivalent to £71.33 in 2005 pounds.