More on the Legal Drinking Age and Traffic Fatalities

I talked last week about the pros and cons of lowering the drinking age back to 18. One of the cons that I had assumed was that lowering the drinking age would increase the number of traffic fatalities in the 18-20 cohort.

A study from NBER disputes this argument. Miron and Tetelbaum looked at the data from different states that voluntarily raised their drinking ages to 21 before federal law tied highways funds to that age in 1984 -- forcing to states to raise the age. They wanted to understand the time course of changes in traffic fatalities both before and after the implementation of different laws (called in their study Minimum Legal Drinking Ages or MLDAs) for the 18-20 cohort.

Their primary argument is that most of the reduction in traffic fatalities in the 18-20 cohort happened in states that raised their MLDA prior to the federal law -- thereby questioning the validity of federal action in that case. (Whether the federal government had the right pass that law was determined in a Supreme Court case South Dakota v. Dole.)

But their study of this data set yields some other interesting conclusions:

  • The trend in traffic deaths was downward before the 1984 federal law was passed, suggesting that other factors may have contributed to the reduction in deaths. These include increased safety measures in cars and improved medical technology.
  • When you look at the time course in deaths after the passage of a higher MLDA in a particular state, most of the reduction in deaths happen the year of the law's passage. The effect was transient and was limited only to states that raised the MLDA before the 1984 federal law.
  • In Model (2), which includes only the states that adopted their MLDA21 [Minimum Legal Drinking Age of 21] during or prior to 1983, there does seem to be a significant and large drop in fatalities during the year of MLDA increase. Though not significant, this decrease predates the adoption of the MLDA21 across states, as illustrated by the negative coefficients on the binary indicators dating back six years before policy enactment. In the year of adoption, fatalities declined 16.7% at the 5% significance level. Yet as early as 1-2 years after enactment, the MLDA is no longer significant and the point estimate increases from -16.7% to -5.4%. More interestingly, the MLDA21 seems to increase fatalities from three to six years after enactment, although the result is not significant. This suggests the fatality-reductions due to MLDA21 policies were transient or even perverse.

    Model (3) restricts the sample to those states that enacted an MLDA21 during or after 1984. Those states experienced increases in 18-20 year old fatalities leading up to enactment of an MLDA21; upon the adoption, there was no significant decrease in fatalities, and as soon as 1-2 years after adoption the increase in traffic fatalities became significant at the 10% level. As with the early adopters, the coefficient on MLDA21 approaches zero five years beyond adoption. (Emphasis mine.)

  • Interestingly enough, the adoption of a MLDA of 19, 20 or 21 by states resulted in a paradoxical increase of about 5% in traffic fatalities for 17 year-olds. You would think this wouldn't be true because their 18 year-old peers wouldn't have legal access to alcohol anymore. The authors try and explain this finding:
  • Several additional findings are also inconsistent with the claim that the minimum legal drinking age reduces traffic fatalities. Table 8 presents regressions analogous to those in Table 6, but using the 17 year old driver fatalities as the dependent variable, find that MLDA19, MLDA20, and MLDA21 all increase traffic fatalities at the 5% level of significance. One explanation is that when the MLDA is 18, more high school students have access to alcohol through peer networks, including 18 year olds. When the MLDA is higher, these peer networks are less effective at obtaining alcohol, so individuals younger than 18 feel pressure to drink intensely at each drinking occasion. Alternatively, when the MLDA is 18, law enforcement monitors the drinking behavior of individuals aged 17 and younger. When the MLDA is 21, this monitoring is spread more thinly, resulting in more drinking among 17 year olds. (Emphasis mine.)

  • Finally, the higher drinking age had at best a very small effect at drinking participation and heavy drinking -- less than 5% depending on the assumptions in the model.

The author's core argument is that the motivation for passing a federal law demanding a 21 MLDA was that it would lower traffic fatalities, but the evidence on the state level suggests that this effect has been minimal and that it is swamped by other factors.

I think it would probably be fair to assume that lowering the drinking age back to 18 would result in at least a short-term increase in traffic fatalities for the 18-20 cohort. On the other hand, these results are one more reason to question MLDA laws as our go-to policies for alcohol abatement. If they aren't working in the way intended, then we need to seek out other options.

Hat-tip: Cato


More like this

If the drinking age were lowered below the driving age, then a teen could legally drink in public and get a few years of experience with it before he's old enough to get his learner's permit.

Other countries have quite different view on the purpose of age limits. In some there is a minimum age for purchase, but no minimum age for consumption. If you'd grown up with wine at the dinner table, drinking would be a normal part of your life, but binge drinking would not.

I second Grackle's comment. Lower the drinking age to 16, and raise the driving age to 19.

Honestly what would rasing the driving age to 19 acomplish? It wouldnt having a ban on the purchase is a much better idea then a consumption age.

As justification for a policy that is massively illiberal(which banning the consumption of an otherwise legal substance by a category of adults unquestionably is), those data are much, much, much less exciting than I would like. I would say that a clear, consistent, and persistent reduction in casualties would be the necessary prerequisite for even taking the question of continuing the policy into serious consideration. If the data are that unimpressive, we might as well wrap the whole thing up.

I heard on NPR this morning that traffic accidents are down. It's being attributed to less driving due to higher gas prices!

Ian: I heard on NPR this morning that traffic accidents are down. It's being attributed to less driving due to higher gas prices!

Or it could be attributed to less driving by groups that are typically bad drivers and are also typically poorer (teenagers and the elderly)...

I second Grackle's comment. Lower the drinking age to 16, and raise the driving age to 19.

I agree. If we could all be honest for just a minute - and obviously we can't or this debate wouldn't exist in the first place - driving a car requires much greater responsibility than handling oneself under the influence of alcohol. Is it not worth noticing that the worst drivers, statistically speaking, are teenagers? IOW, they're going to crash more than other age groups whether they're consuming or not.

Our society isn't lacking appreciation of the dangers of alcohol. What we lack is an appreciation of the dangers of driving.

"Is it not worth noticing that the worst drivers, statistically speaking, are teenagers?"

That depends. Are teenagers the worst because they are inexperienced, or because they are young? I'm sure such a study could easily be done (if it hasn't been done already) comparing teen drivers to older inexperienced drivers that waited to get their license. Does anyone know of any references of that sort?

Well, this is, admittedly, anecdotal, but I received my license at almost 30, after having briefly used a learner's permit in my teens. I learned to drive very quickly, and far more safely, than either my brief attempt in my teens, or the average teenager.

However, on a less anecdotal level, at 16, one's brain is still not fully developed, it is not able to handle complex decisions as well as an adult's brain, or to focus on a task at hand as well.

I would like to support raising the minimum driving age to 18, independent of what the drinking age is (but no higher, because that would be just as much discrimination-against-adults as the minimum drinking age currently is) but I still too vividly remember what it was like to be a teenager with no access to a car in the far suburbs of Los Angeles. I can't support additional restrictions on driving until after there are massive, countrywide improvements in public transit.

I think if we're serious about addressing harmful attitudes and practices surrounding alcohol, we need to focus less on when we allow people to start drinking and more on how.

The current model is that young people are indoctrinated into drinking culture by their equally inexperienced peers, often in secret, often in the form of binge drinking. In the best-case scenario where they abstain from drinking until age 21, we then send them off on their birthday with friends of similar age to get absolutely blitzed.

When it comes to driving, we have the learner's permit- a transitional period where novices are initiated to driving by responsible adults, often their parents. Is it so unthinkable to apply the same principle to alcohol?

Lower the drinking age to 18 or 19, but allow 16 and 17 year-olds to drink under the supervision of their parent or guardian. Give parents the legal leeway to do what responsible parents have been doing for generations: let their kids have a glass of wine with Christmas dinner, relax with a beer on the 4th of July - in short introduce them to normal adult social drinking.

Notice I specifically said parental supervision as opposed to adult supervision. I can certainly imagine scenarios in the latter case that would have all the kids in the neighbourhood gravitating towards the least responsible adults in their social circle. Now, inevitably there are going to be parents who initiate their children into pathological drinking habits, but this is true of everything from driving to education to relationships, and doesn't justify depriving responsible parents of useful tools.

I haven't been following the driving regulation statistics for a couple of decades, but I remember that the complicated, expensive, and thorough systems used in Japan and Germany (graduated licensing for motorcyclists; time and money -> tiny bike -> small bike -> time and money -> medium bike -> time and money -> large bike) did not seem to be effective at reducing negative outcomes. It would be nice to have drivers behave responsibly, but the way the traffic laws are enforced does not encourage that. Many people are ignorant of the basics of traffic - the appropriate way to use turn signals, merge lanes, . . . . The traffic laws exist to keep the vehicles from bumping into one another. Adults are not much better than teens at understanding traffic laws. Why can't we do a better job of teaching and testing responsible driving?

Outright bans do not teach, or encourage, responsible use - not that we should be encouraging use of alcohol. We should not, but we should recognize that people will consume alcohol regardless of the obstacles created by we know what's good for everyone else crowd. If only they would recognize that what is best for everyone else, is to be left alone by the we know what's good for everyone else crowd. Just because something might be a good idea doesn't mean it should be a law.

While the brain matures at different stages, one of the things that we ignore is the effect of environment on the development of the brain. A child given increasing responsibility to make decisions for him/herself from an early age is not going to behave the same, when a teenager, as one protected from responsibility and risk for all of his/her life. We have been increasingly removing responsibility from people's lives. How does that lead to a more responsible society. We have increasingly been removing the appearance of risk from anyplace it might rear its ugly head, but there is no reason that we should believe this has led to less risk. It has just led to less understanding of risk.

Responsibility is understanding the consequences of one's actions and behaving accordingly. Responsibility is not preventing people from making choices, because they might make a bad choice. That only indoctrinates a lack of decision making ability. There could not be a worse choice.

It seems to me that a place like Iowa should be a very good test case for the hypothesis that raising the drinking age decreases drunk driving deaths.

I don't know how it worked in other states, but in Iowa, the drinking age changed but drinkers were grandfathered in. Therefore, the drinking age was 19 on something like Jan 1, 1987 (there or abouts), and everyone who was 19 on or before that date was allowed to drink (then there's me, who turned 19 on March 31 of that year - I wasn't the worst off, but close). What that means is that the drinking age moved to 20 in Jan 1988, and didn't move to 21 until 1989.

If increasing the drinking age leads to fewer deaths, then one would expect the number of deaths to keep dropping for those years.

Other states that started at 18 and grandfathered in would have even another year to look for the trend.

I've always figured that if courts can rule that a minor can be tried as an adult, then a minor should be allowed to use the court to gain the benefits of the adult.

"The judge has ruled that little Timmy has the maturity to be treated as an adult, and therefore is allowed to partake in adult beverages."

Of course, Timmy bears all the responsibility of his actions at that point, too.

The more fun scenerio is when the request is denied. "The court rules that Little Jimmy is not mature enough to be considered an adult." And then Jimmy goes and rapes the neighbor's pet goat. What is the court going to do? Change their mind?

It's terribly inconsiderate to tell an 18 year old enlisting
"Here's a rifle, go shoot some baddies, but no drinking - you're not responsible enough to take care of yourself. We can't trust you on the streets of our cities or with your own body."

By Sortofanonymous (not verified) on 27 Aug 2008 #permalink

It's funny this would come-up here (or maybe not -- it WAS a news story), but I just sent-out another giant e-mail to all my friends (I gotta' get a blog) with a section on this topic:

Drinking age (back) to 18?
Most of you will have heard my soapbox speech about this. The Reagan administration used coercive strong-arm tactics against any state that didn't raise its drinking age to 21, because, as they said, it would "reduce car accidents involving alcohol." Think about it: I bet we could reduce "car accidents involving alcohol" by 50% by the simple expedient of not allowing females to drink! That's a good idea, eh? What about prohibiting anyone over 55 from drinking? I believe the reason young people were picked-on had NOTHING to do with alcohol itself, or cars, or accidents, and everything to do with MUSIC. Yes, MUSIC. 'Remember the eighties? Night-clubs were thriving; society was divided, and those clubs were fermenting-up a whole generation of activists by exposing them to the likes of The Clash, Dead Kennedys, Ramones, Exploited, Heathen Girls, Millions of Dead Cops,.... _I_ think the drinking laws were a deliberate attempt by conservative forces to squelch the alternative "Punk" movement, and give police an excuse to go-after punks, teenagers, whomever they thought socially dangerous. So there. Compare this to Seattle's infamous "Teen Dance Ordinance" that was a transparent effort to suppress the "Grunge" danger perceived by The Powers. And don't get me started on misleading labeling of statistics: If I were stopped at a traffic light with my overindulged friend sleeping in the back seat, and a completely sober bank-robber fleeing a scene ran into me, it would be tallied as an "alcohol-related accident." The anti-fireworks forces do the same thing. Look at the DHMO site:

By OrchidGrowinMan (not verified) on 28 Aug 2008 #permalink

i think the drinking age should be lowered because if you alllowed kids over the age of 18 to drink then maybe it would not be as fun to go behind peoples back and do it because that is the only reason kids drink because they are not allowed to drink and that is my opion

By shelby bullock (not verified) on 16 Dec 2008 #permalink

The governement shouldnt tell people what they shouldnt put in there own bodies, this is just my personal opinion. Prohibition will only cause more of the item to be used, case in point the prohibition of alcohol. If people are smart enough to think for themselves and learn the pros and cons, without the lies people spread to get people not to do it because they dont like it, then maybe they might not or might feel that it is a personal choice not a choice of the government. If you do not like what I have as an opinion you can tell me or go do something else, in the end it's your choice. :)