One of the reasons drunk driving is of such concern to police is that it is an offense committed by a broad spectrum of the population, including those who are otherwise generally law-abiding. An estimated one-fifth to one-fourth of U.S. drivers admit to having driven after drinking at least once within the past year, 4 and about five percent estimate that they were legally impaired. 5 Drunk drivers come from all parts of the population spectrum, but are more likely to be male,6 white or Hispanic,7 between 25 and 44 years of age, 8 unemployed or working class,9 and unmarried.10 Drunk drivers are more likely to be heavy drinkers or to have drinking problems. 11 Drinking drivers under 21 years of age are about twice as likely as older drivers to be involved in fatal vehicle crashes. 12