International policies on alcohol impaired driving: are legal blood alcohol concentration (BAC) limits in motorized countries compatible with the scientific evidence?

Borkenstein et al. (1974) study indicated that drivers with BACs of 0.05 to 0.09 per cent were twice as likely to crash as drivers with a zero BAC. Drivers with BACs from 0.10 to 0.14 per cent were ten times as likely to have a fatal crash in 1964. There have been numerous efforts during the history of motorized countries to control the consumption of alcohol and the problems associated with it through legislative mandate, it was not until the 1970s that acceptance of legal BAC (Blood Alcohol Concentration) limits laws became widespread. In particular, as more and more people drive automobiles, the number of traffic accidents involving drunken drivers has soared, and many of these are known to be related to the consumption of alcohol. Thus, legislators find themselves under increasing pressure to find a reasonable and fair solution to the question of alcohol impaired driving, as the scientific evidence about alcohol consumption level and psycho motor functions impairment came to clear. A landmark event in the development of policies regarding impaired driving was the establishment of the fact that consumption of alcohol does, in fact, increase the probability of traffic crashes. Legal limit laws specify a maximum permissible BAC limit for drivers. Currently, a BAC laws range from zero tolerance and 0.02 to 0.10% constitutes prima facie evidence in most countries for 'Driving under Influence of Alcohol.' This latter standard is too permissive, as driving skills deteriorate and crash involvement risk increases beginning at 0.02%. There are consequences attached to setting a BAC limit so high that a 72 kg man can drink five bottles of beer and still be under legal limit. In this sense high legal BAC limit may influence people to make bad estimates of their relative risk of injury or death while driving. Provided there is adequate political will, millions of lives could be saved in the coming years. This review is an attempt to examine in detail the available information about legal BAC limit laws, and issue of considerable interest to both policy makers and the public.