Although the number of deaths attributed to drunk driving has shown a slight decrease over the past few years, alcohol impairment continues to be a major factor in motor vehicle crashes. In 1996, 34% of the drivers of passenger vehicles and 41% of the motorcyclists who died in highway accidents had blood alcohol levels of 0.10% or above, according to the Insurance Institute for Highway Safety. (Although many factors affect blood alcohol levels, on average a 170-pound man would reach a blood alcohol level of 0.10 by having four or five drinks in one hour, and 137-pound woman having three drinks in the same period.) However, alcohol has been observed to affect driving ability and the likelihood of an accident at blood alcohol levels as low as 0.02%. And the probability of a crash begins to increase significantly at a blood alcohol level of 0.05 and rises sharply at 0.08 and above.

Among teenagers...