Which Ancillary Laws Actually Work to Reduce Teen Drinking? (Spoiler Alert: Almost None)

The legal drinking age (at least in terms of purchase and public possession) has been 21 in all 50 states and DC since 1988 (notwithstanding the Louisiana Loophole through 1995), but states and localities have differed since then on the "ancillary" laws that are used to prop up the 21 drinking age.  These laws include, among others:

• Laws against private possession and/or consumption 
• Internal possession laws
• Laws against furnishing alcohol to people under 21
• Dram shop liability laws
• Social host liability laws (civil or criminal)
• Keg registration 
• Use alcohol and lose your license ("use and lose" laws)
• Zero-tolerance laws for DUI
• Fake ID laws and ID scanner laws
• Age limits for serving alcohol

Most if not all of these laws have been studied to some extent, with mixed results and even some serious plot twists.  Most of these studies have been conducted by MADD-affiliated researchers such as James C. Fell, Robert Voas, and Ralph Hingson, so they should probably be taken with at least a grain of salt, if not a whole pound.  But even with this potentially significant bias, most of these laws were found to have either no effect, inconsistent effects, very small effects, or even perverse effects in terms of "alcohol-related" traffic fatalities among young people.

If these laws (and by extension, the 21 drinking age itself) did work as intended, one would expect the effectiveness of these laws to show up not only in traffic fatality statistics (which are the tip of a very large iceberg), but also in surveys of teen drinking as well, especially when recent data are studied.  A 2014 study done by Vanessa H. Sacks et al. of Child Trends examined the relationship between 14 different ancillary laws (and alcohol taxes) and both current drinking (any in the past 30 days) and "binge" drinking (5+ drinks "within a couple of hours") among high school students from 2005-2011 as reported on the Youth Risk Behavior Survey (YRBS) of those years.  The 14 laws studied were the following:

• Laws against consumption of alcohol by people under 21
• Exceptions to possession laws
• Exceptions to furnishing laws
• Social host liability laws 
• BAC limits for people under 21 (i.e. zero-tolerance laws)
• Use-and-lose laws (strength measured in three different ways)
• ID scanners in retail locations
• Keg registration
• Age limits for serving alcohol 
• Beer excise taxes in 2005
• Distilled spirits excise taxes in 2005

And the results?  All but three such laws had no significant or even perceptible effect individually on either current drinking or "binge" drinking rates.  The only three that did have any statistically significant correlation were:

• Beer taxes were significantly and negatively associated with both current drinking and "binge" drinking rates.  No surprise there, as this dovetails nicely with the reams of evidence that have found similar results.  (Distilled spirits taxes showed no correlation either way, but that apparently null result is likely due to multicollinearity since beer and liquor taxes are highly correlated with each other).
• Keg registration laws were significantly and negatively correlated with current drinking, but not "binge" drinking, in one of two models.  This result should probably be interpreted with caution though, given how multiple other studies have found a positive correlation between keg registration and "alcohol-related" youth traffic fatalities.
• Use-and-lose laws (i.e. driver's license penalties for mere possession or consumption of alcohol) showed a positive correlation with current drinking, that is, such laws seemed to perversely increase teen drinking.
• And the real kicker: after controlling for drinking rates in previous years and the number of ancillary laws in previous years, states with a greater total number of such policies perversely had higher rates of both current and "binge" drinking.  But drinking rates in previous years did not predict the number of policies in place in later years, thus ruling out the possibility of reverse causation.

Thus, while the researchers caution that these results alone are not definitive enough to establish causation, it is quite clear that such results certainly cast serious doubt on the effectiveness of such laws, and by extension the 21 drinking age itself, in reducing teen drinking and related problems.  With the notable exception of alcohol taxes, the effects of such laws are most likely negligible or even perverse overall.  That, of course, dovetails rather nicely with Miron and Tetelbaum (2009), who found that raising the drinking age to 21 seems to have had "only a minor impact on teen drinking".  And we couldn't agree more.