Many youth under age 21 still drink, despite the current legal drinking age. Doesn't that prove that this policy is ineffective?

While some youth may choose to consume alcohol before age 21, studies show that they consume less and suffer fewer secondary effects such as alcohol-related injuries when the drinking age is 21. (Wagenaar, A. C. (1993). Minimum drinking age and alcohol availability to youth: Issues and research needs. In: Hilton, M.E., Bloss, G., eds. Economics and the Prevention of Alcohol-Related Problems. Bethesda, MD: National Institute on Alcohol Abuse and Alcoholism, 175–200. (NIAAA Research Monograph No. 25, NIH Publication No. 93-3513.)

Studies also indicate that delaying onset of drinking will substantially reduce the risk of alcohol problems and dependence later on in life. (Task Force of the National Advisory Council on Alcohol Abuse and Alcoholism, National Institute on Alcohol Abuse and Alcoholism. A Call to Action: Changing the Culture of Drinking at U.S. Colleges (Washington, D.C.: National Institutes of Health, 2002.) http://www.collegedrinkingprevention.gov)

Further, when the legal drinking age is 21, those under age drink less than when the drinking age is lower, and they continue to drink less through their 20s. (O'Malley, P. M., & Wagenaar, A. C. (1991). Effects of minimum drinking age laws on alcohol use, related behaviors and traffic crash involvement among American youth: 1976–1987. Journal of Studies on Alcohol, 52, 478–491.)

"There is also some 'trickle-down' effect in that when youth get alcohol they often give it to even younger teens." In a 2005 survey commissioned by the American Medical Association, 65 percent of teens under the age of 18 indicated that it was easy to get alcohol through a relative or sibling who is older than 21. (Roan, S. (2005). When parents buy the booze. Los Angeles Times. http://articles.latimes.com/2005/aug/08/health/he-drinking8) (Jones-Webb, R., Toomey, T., Miner, T., Wagenaar, A. C., Wolfson, M., & Poon, R. (1997). Why and in what context adolescents obtain alcohol from adults: A pilot study. Substance Use & Misuse, 32, 219–228; ) "When the legal age is 21, 19- and 20-year-olds can often obtain alcohol from their friends. When the drinking age was 18 and 19, 17- and even 16-year-olds were often able to get alcohol from their friends. If the drinking age is lower, more alcohol will be available to younger high school students and perhaps even middle school students." (Wagenaar, A. C., & Toomey, T. L. (2002). Effects of minimum drinking age laws: Review and analyses of the literature from 1960 to 2000. Journal of Studies on Alcohol, Supplement 14, 206-225.)