MLDA laws have been among the most widely studied substance use policies in the world, and most studies have found that higher MLDA’s led to later initiation of drinking and reduced frequency of heavy drinking (e.g., Cook and Moore, 2001, Dee 1999, and O’Malley and Wagenaar 1991). In a study using 28 years of cross-sectional surveys from the Monitoring the Future Study (MTF), Carpenter et al (2007) found that about 60% of high school seniors reported drinking in the past 30 days, and 34% reported drinking 5 or more drinks in a row at least once in the past two weeks; exposure to an MLDA of 18 increased the proportion of drinkers by about 3 percentage points, and increased the proportion reporting heavy episodic drinking by about 1.7 percentage points. Other studies have found that higher MLDA’s led to fewer alcohol-related traffic crashes (e.g. Kypri et al, 2006, Ponicki et al 2007, Schults et al 2001), and lower rates of crime and suicide among persons below age 21 (e.g., see reviews in Cook 2007, Carpenter et al 2007, and Wagenaar
