Minimum legal drinking age (MLDA) laws were established in the United States after the repeal of Prohibition in 1933. Many states set the MLDA at 21 during that time. When the voting age was lowered from 21 to 18 in 1971, many states lowered their drinking age to 18 or 19. Studies in the 1970s and 1980s showed significant increases in alcohol-related crashes involving youth aged 18 to 20 in states that lowered their drinking age (Brown & Maghsoodloo, 1981; Cook & Tauchen, 1984; Ferreira & Sickerman, 1976; Wagenaar, 1983b; Williams, Rich, and Zador, 1975). Several studies in the early 1980s also found reductions in traffic crashes (Wagenaar, 1983b) and alcohol-related or total crash deaths when drinking ages were raised (Hingson et al., 1983; Wagenaar, 1981; Williams et al., 1983). Consequently, the U.S. Congress adopted the National Uniform Drinking Age 21 Act, which provided a substantial financial incentive for states to adopt a MLDA of 21, and President Reagan signed the bill into law in 1984. Since 1988, the MLDA has applied to age 21 for both the purchase and possession of alcohol in all 50 states and the District of Columbia. Between 1982 and 1998, the population-adjusted rate involving drinking drivers aged 20 and younger in fatal crashes in the United States decreased 59% (Hedlund, Ulmer, and Preusser, 2001). MLDA-21 laws have been shown to be independently associated with part of this decline (O'Malley & Wagenaar, 1991; Shults et al., 2001; Toomey, Rosenfeld, and Wagenaar, 1996; Voas, Tippetts, and Fell, 2003). The National Highway Traffic Safety Administration (NHTSA) has estimated that MLDA laws save approximately 900 lives a year in traffic fatalities alone (Arnold, 1985; Kindelberger, 2005; NCSA, 2005; Womble, 1989). Other studies show reductions in homicides (Jones, Pieper, and Robertson, 1992; Parker & Rebhun, 1995), suicides (Birckmayer & Hemenway, 1999), and unintentional injuries (Jones et al., 1992) by 18- to 20-year-olds associated with raising the MLDA to 21. Despite the laws raising the drinking age to 21, underage drinking is prevalent in America. Even facing strong evidence of the effectiveness of MLDA-21, there are movements in some states and by some organizations to lower the drinking age again (Wasley, 2007). There is no evidence that lowering the MLDA will reduce the underage drinking problem. Conversely, there is strong evidence that lowering the drinking age will increase youthful alcohol consumption and alcohol-related injuries and fatalities.
Despite the federal incentive and state laws raising the drinking age to 21, underage drinking is prevalent in America. Underage drinking is attributed to an estimated 5,000 deaths (U.S. Department of Health and Human Services, 2007) and 2.6 million injuries and other harm annually (Miller et al., 2006). This costs U.S. society approximately $62 billion each year (Miller et al., 2006). To strengthen drinking age laws and reduce the injuries and deaths associated with youthful drinking, states have also enacted other legislation addressing keg registration, the use of fake identification, and minimum server/seller age to make it more difficult for youth to obtain alcohol from retail sources. Social host laws target those who host underage drinking parties and focus on preventing illegal provision of alcohol to youth. Other expanded laws focus on preventing youth from drinking and driving; for example, the zero-tolerance law makes it an offense for drivers aged 20 and younger to operate a vehicle with any amount of alcohol in their systems (blood alcohol concentration [BAC] >.00). Some provisions of recent the graduated driver licensing (GDL) laws have night restrictions on driving by youth to reduce the risk of drinking and driving, most of which occurs at night. Use and lose laws, which authorize the suspension of driving privileges for underage alcohol violations (i.e., purchase, possession, or consumption of alcohol), aim to provide meaningful sanctions for youth who violate the MLDA laws. At least fourteen expanded laws strengthen the earlier core MLDA-21 laws (prohibiting possession and purchase) and increase the states' alcohol prevention efforts targeting youth (IIHS, 2006; NHTSA, 2006; NIAAA, 2007).
There is substantial variation among states in the comprehensiveness of such legislation. For example, although it is illegal in all states and the District of Columbia for underage youth to possess alcohol in public, it is legal in 20 states for youth to consume alcohol in public. Further, some states have zero-tolerance laws that are unenforceable because police officers cannot take a youth into custody or transport them to the police station for a breath test unless they can demonstrate that the youth has a BAC higher than the adult illegal limit of .08 BAC (Ferguson, Fields, & Voas, 2000). Not all states have GDL laws, and some states do not have provisions in their GDL laws that restrict unsupervised driving at night when alcohol is most likely to be a factor (Williams & Preusser, 1997).
The public generally assumes that the MDLA-21 is embodied in a single law. In actuality, the MLDA-21 laws have multiple components, and the laws vary considerably from state to state. No state has all 16 law components or regulations that have been documented (Fell et al., 2008). Of the 16 underage drinking laws that states could adopt, only Utah has as many as 15 of them, and Kentucky has only 7 of the 16. Laws that provide for a drivers license sanction (suspension or revocation) if a youth is cited for underage drinking have been shown to be effective (Ulmer, Shabanova, & Preusser, 2001), yet only 37 states have such "use and lose" laws. Although it is illegal in all states and the District of Columbia for an underage youth to use a fake identification, it is illegal in only half the states (25) to transfer or produce fake identifications.
Thus, the current U.S. effort to control underage drinking involves a variable package of legislative policies, and the level and intensity of enforcement of these policies is relatively unknown at the state level. Consequently, if the MLDA were to be lowered from 21 to 18 in any state for the two core laws (possession and purchase), it most likely will need to be lowered for the expanded laws in that state as well.
Despite the current variability in underage drinking laws and their enforcement across the States, the two core laws have shown significant effects in reducing underage drinking consequences. These laws could be even more effective if all states would adopt all of the components and limited the exceptions (National Research Council and Institute of Medicine [NRC/IOM], 2004).