Yes. Young drivers are less likely than adults to drive after drinking alcohol, but their crash risk is substantially higher when they do. This is especially true at low and moderate blood alcohol concentrations (BACs) and is thought to result from teenagers' relative inexperience with drinking, with driving, and with combining the two.^1,2

In 2006, 25 percent of 16-20-year-old passenger vehicle drivers fatally injured in crashes had BACs of 0.08 percent or higher. The percentage of fatally injured drivers with high BACs was much lower among females (15 percent) than among males (29 percent), and also was lower among 16-17-year-old drivers (18 percent) than among 18-19-year-old (25 percent) or 20-year-old (33 percent) drivers.

Drivers ages 16-20 with BACs of 0.05-0.08 percent are far more likely than sober teenage drivers to be killed in single-vehicle crashes — 17 times more likely for males, 7 times more likely for females. At BACs of 0.08-0.10, fatality risks are even higher, 52 times for males, 15 times for females.²

Yes. Minimum alcohol purchasing age laws limit access to alcohol among teenagers. For a long time, the legal age for purchasing alcohol was 21 in most of the United States. In the 1960s and early 1970s, many states lowered their minimum purchasing ages to 18 or 19. However, states gradually restored higher minimum purchasing ages so that, by the end of 1984, 23 states had minimum purchasing ages of 21, and federal legislation was enacted to withhold highway funds from the remaining 27 states if they did not follow suit. Since July 1988, the minimum alcohol purchase age has been 21 in all 50 states and the District of Columbia.³

All 50 states and the District of Columbia also have established lower blood alcohol thresholds that are illegal per se for drivers younger than 21. Federal legislation enacted in 1995 that allowed for the withholding of highway funds played a role in motivating states to pass such zero tolerance laws. Typically, these laws prohibit driving with a BAC of 0.02 percent or greater.

Yes. When minimum alcohol purchasing age laws were lowered in many states in the 1960s and early 1970s, Institute research indicated an increase in the number of drivers younger than 21 involved in nighttime fatal crashes.⁴ When a number of states restored higher purchasing age laws as a result of this and other studies, Institute researchers in 1981 evaluated this development in 9 states, finding that nighttime fatal crashes among young drivers were reduced by 28 percent.⁵ A subsequent study in 26 states that raised minimum purchasing ages during 1975-84 estimated a 13 percent reduction in nighttime driver fatal crash involvement.⁶

Studies of zero tolerance laws indicate they reduce crashes among drivers younger than 21. A study of 12 states that passed zero tolerance laws reported a 20 percent reduction in the proportion of fatal crashes that were single-vehicle nighttime events (crashes likely to involve alcohol impairment) among drivers ages 15-20.⁷

IIHS support for 21 drinking age

Trends in alcohol involvement in fatal crashes can be monitored through the National Highway Traffic Safety Administration's Fatality Analysis Reporting System, a census of all fatal crashes in the United States. During the 1980s, the percentages of fatally injured drivers with BACs of 0.08 percent or higher declined among drivers of all ages. Reductions among young drivers were greatest, in part because of changing minimum alcohol purchasing age laws. In 1982, fewer than half of the states had a minimum purchasing age of 21, and 53 percent of all fatally injured drivers younger than 21 had BACs of 0.08 percent or higher. This statistic declined dramatically as states adopted older purchasing age laws. By 1995, it had declined to 24 percent, the biggest improvement for any age group, and was 27 percent in 2006. Between 1996 and 2005, the proportion of fatally injured drivers with positive BACs fell by 16 percent for 16 year-olds and 5-9 percent for 17-19 year-olds.⁸

States and communities need to make it more difficult for teenagers to purchase alcohol. During 1990-91, Institute researchers found that 19-20 year-olds could easily buy a six-pack of beer in Washington, DC, and a New York City suburb.⁹ But in two New York counties where police recently had cracked down on underage alcohol purchases, youths were less successful. In these studies, the underage purchasers generally were not even asked by sellers for proof of their ages. During 1994-95, Institute researchers surveyed high school and college students younger than 21 in New York and Pennsylvania about alcohol use and purchasing. Fifty-nine percent of college students and 28 percent of high school students in New York and 37 percent of college students and 14 percent of high school students in Pennsylvania reported they had used false identification to obtain alcohol.¹⁰ According to the 2006 Monitoring the Future survey, almost all (92 percent) of high school seniors believe it is fairly easy or very easy to get alcohol.¹¹

One barrier to rigorous enforcement of minimum legal drinking age laws is low funding for state alcohol beverage control agencies. This may inhibit not only the identification of servers, sellers, and purchasers who are violating the law but also the timely application of administrative penalties. Establishments do not always check teenagers' identification cards to establish age, and some teenagers use borrowed/altered or false identifications that are difficult to distinguish from official licenses.¹² Research shows that increased sales law enforcement can reduce the sale of alcohol to minors.¹³ Clearly, stepping up enforcement of minimum alcohol purchasing age laws is needed to make them more effective.

Institute research has shown that the potential of zero tolerance laws has not been realized. Researchers found such laws difficult to enforce in some states because police must suspect that a young driver has a high BAC before administering an alcohol test for any measurable BAC.¹⁴ Enforcement of zero tolerance laws reinforces enforcement of underage drinking laws. However, zero tolerance laws are difficult to enforce independent of DUI because offenders with low BACs are not likely to display the erratic driving that results in drivers with high BACs being stopped.³ Institute surveys of young people in three states found limited knowledge about zero tolerance laws, and many of those who knew about the laws did not believe they often were enforced.¹⁵ When zero tolerance laws are enforced they are effective. An Institute study of Washington state's zero tolerance law found that the law increased the likelihood that an underage person would be sanctioned for drinking and driving, especially among drivers with BACs less than 0.08g/dL.¹⁶ Full enforcement of zero tolerance laws accompanied by publicity about the enforcement will be needed to increase effectiveness. Changes to the laws may encourage enforcement efforts.