Setting the Minimum Legal Drinking Age at 21 Years
Publication Date: 12/07/2009
The Problem:
The operation of motor vehicles while intoxicated is a major public health problem. Each year in the United States roughly 13,400 people die and an additional 255,500 are injured in motor vehicle crashes involving an alcohol-impaired driver. In 2006, these crashes accounted for almost a third of all U.S. traffic-related deaths. Drivers age 16 to 20 who engage in drunk driving pose an especially dangerous risk to themselves and other motorists. CDC: Impaired Driving Factsheet.
The Law:
All U.S. states currently set the minimum legal drinking age at 21 years (MLDA21). Federal legislation withholds federal highway funds from states that do not adopt an MLDA of 21 years (23 U.S.C. § 158). For examples of MLDA21 laws, see TX Alcoholic Beverage Code § 106.04 (Texas), Conn. Gen. Stat. 30-1(12) and Conn. Gen. Stat. §30-89 (Connecticut).
The Evidence:
Two independent systematic reviews of the relevant studies of this intervention have found a robust association between raising the MLDA to 21 and reductions in alcohol-related crashes. In a Community Guide systematic review, Shults et al. reviewed 33 studies that examined the effect of MLDA21 on fatal and nonfatal crashes likely to have involved alcohol. Shults, et al. Reviews of Evidence Regarding Interventions to Reduce Alcohol-Impaired Driving. Am J Prev Med. 2001;21(4S):66-88. Seventeen of the underlying studies evaluated the impact of raising the MLDA to 21, 11 evaluated laws that lowered the MLDA, and remaining 18 used regression analysis to measure changes in both directions. The review found a median reduction in alcohol-related crashes of 17 percent associated with raising the MLDA and a median increase of 8 percent in alcohol-related crashes associated with lowering the MLDA.
Wagenaar and Toomey reviewed 48 studies that measured the impact of MLDA21 on alcohol consumption and reviewed 57 studies that measured the impact of MLDA21 on alcohol-related crashes. Wagenaar, Toomey. Effects of Minimum Drinking age Laws: Review and Analyses of the Literature from 1960 to 2000. Journal of Studies on Alcohol. 2002(14 Suppl):206-25. Across the 48 studies, the authors identified 27 measures finding a statistically significant inverse relationship between MLDA21 and alcohol consumption (8 found a statistically insignificant inverse relationship; 5 found a positive relationship). Some of the measures included, for example, self-reported alcohol consumption and sale of particular alcoholic beverages. Fifty-two measures were indentified finding a statistically significant inverse relation between MLDA21 and crashes (12 found a statistically insignificant inverse relationship; 2 found a positive relationship). These measures included a broad range of types of injuries and crashes outcomes (e.g., nighttime fatal crashes, alcohol-related crashes).
The Bottom Line:
In the judgment of a Community Guide expert panel and the authors of a peer-reviewed systematic study, there is strong evidence to support the effectiveness of MLDA21 as an intervention aimed at reducing alcohol involved motor vehicle crashes.
Additional Information:
The Community Guide provides online access to a table summarizing the results of each study it reviewed.
Additional Resources: The Community Guide
What are Evidence Briefs?
A Public Health Law Research Program “Evidence Brief” summarizes the research assessing the effect of a specific law or policy on public health.
Evidence Briefs are prepared by the staff of the National Program Office. Briefs are based on systematic literature reviews conducted by highly-regarded scholars and published by credible organizations or peer-reviewed journals. Evidence Briefs digest the best available evidence, but readers should bear in mind that even the best evidence may have limitations or deficiencies.
The evidence briefs are organized by topic and intervention. Each law or policy is classified as “effective,” “uncertain” or “harmful,” according to the conclusions of the expert reviewers. These are not independent conclusions of the NPO, nor do they reflect the views of the Robert Wood Johnson Foundation.
About the Links
Each Evidence Brief includes links to the study on which it is based. In many cases, the study is available in the public domain, but access to some may require a subscription.
