Economists Predict Marijuana Legalization Will Produce 'Public-Health Benefits'

In their
2012 book Marijuana
Legalization: What Everyone Needs to Know, Jonathan
Caulkins and three other drug policy scholars identify the impact
of repealing pot prohibition on alcohol consumption as the most
important thing no one knows. Are cannabis and alcohol complements,
so that drinking can be expected to increase along with pot
smoking? Or are they substitutes, implying that more pot smoking
will mean less drinking? For analysts attempting to calculate the
costs and benefits of legalizing marijuana, the question matters a
lot, because alcohol is considerably more dangerous than marijuana
by most measures. If the two products are complements, states that
legalize marijuana can expect to see more consumption of both,
exacerbating existing health and safety problems. But if the two
products are substitutes, legalizing marijuana can alleviate those
problems by reducing alcohol consumption.

Reviewing the evidence in the Journal of Policy Analysis and
Management, Montana State University economist D. Mark
Anderson and University of Colorado economist Daniel Rees find
that “studies based on clearly defined natural experiments
generally support the hypothesis that marijuana and alcohol are
substitutes.” Increasing the drinking age seems to result in more
marijuana consumption, for instance, and pot smoking drops off
sharply at age 21, “suggesting that young adults treat alcohol and
marijuana as substitutes.” Another study found that legalizing
marijuana for medical use is associated with a drop in beer sales
and a decrease in heavy drinking. These results, Anderson and Rees
say, “suggest that, as marijuana becomes more available, young
adults in Colorado and Washington will respond by drinking less,
not more.”

That conclusion is consistent with earlier research
in which Anderson and Rees found that enacting medical marijuana
laws is associated with a 13 percent drop in traffic fatalities.
That effect could be due to the fact that marijuana impairs driving
ability much less dramatically than alcohol does, although the fact
that alcohol is more likely to be consumed outside the home
(resulting in more driving under its influence) may play a role as
well.

Anderson and Rees also consider the impact of legalization on
pot smoking by teenagers. Looking at data from the Youth Risk
Behavior Survey from 1993 through 2011, they see “little evidence
of a relationship between legalizing medical marijuana and the use
of marijuana among high school students.” Narrowing the focus to
California after medical marijuana dispensaries began
proliferating, they find “little evidence that marijuana use among
Los Angeles high school students increased in the mid-2000s.” It
actually went down from 2007 and 2009, then rose from 2009 to 2011,
but that increase was mirrored in three comparison cities (Boston,
Chicago, and Dallas) without dispensaries.

Anderson and Rees note that UCLA drug policy expert Mark
Kleiman, who co-wrote Marijuana Legalization and has
been advising Washington’s cannabis regulators, recently
described a worst-case scenario for legalization featuring an
increase in heavy drinking, “carnage on our highways,” and a
“massive” increase in marijuana consumption among teenagers.
“Kleiman’s worst-case scenario is possible, but not likely,” they
conclude. “Based on existing empirical evidence, we expect that the
legalization of recreational marijuana in Colorado and Washington
will lead to increased marijuana consumption coupled with decreased
alcohol consumption. As a consequence, these states will experience
a reduction in the social harms resulting from alcohol use. While
it is more than likely that marijuana produced by state-sanctioned
growers will end up in the hands of minors, we predict that overall
youth consumption will remain stable. On net, we predict the
public-health benefits of legalization to be positive.”

I noted
Rees and Anderson’s research on marijuana legalization and car
crashes in Reason last year.