More Pot, Less Crime: Medical Marijuana States See Drops in Assaults and Homicides

A
study published by the online journal PLOS
One yesterday finds that adoption of medical marijuana
laws is not associated with an increase in crime and may even
result in fewer assaults and homicides. Robert G. Morris and three
other University of Texas at Dallas criminologists looked at trends
in homicide, rape, robbery, assault, burglary, larceny, and auto
theft in the 11 states that legalized marijuana for medical use
between 1990 and 2006. While crime fell nationwide during this
period, it fell more sharply in the medical marijuana states, even
after the researchers adjusted for various other differences
between states. Morris and his colleagues suggest that the
substitution of marijuana for alcohol could explain this result,
although they caution that the extra reduction in crime might be
due to a confounding variable they did not consider.

What seems clear is that these crime data do not support the
notion that making marijuana more readily available drives up crime
rates, whether because of marijuana’s effect on behavior (including
use of other drugs) or because of robberies associated with
cash-heavy cannabusinesses:

The central finding gleaned from the present study was that MML
[medical marijuana legislation] is not predictive of higher crime
rates and may be related to reductions in rates
of homicide and assault. Interestingly, robbery and burglary rates
were unaffected by medicinal marijuana legislation, which runs
counter to the claim that dispensaries and grow houses lead to an
increase in victimization due to the opportunity structures linked
to the amount of drugs and cash that are present….This is in line
with prior research suggesting that medical marijuana dispensaries
may actually reduce crime in the immediate vicinity.

How relevant is research on medical marijuana laws to the debate
about broader forms of legalization? Highly relevant, if you take
the view that medical marijuana is mostly a cover for recreational
use, as prohibitionists tend to argue. In truth, the legal regimes
governing the medical use of marijuana range from very strict (such
as New Jersey’s) to very loose (such as California’s). But it is
fair to say that a lot of people with doctor’s recommendations in
the looser states are recreational users in disguise. It therefore
makes sense that legalizing medical marijuana would be accompanied
by a decline in drinking, as Morris et al. suggest. Such a
substitution effect may also explain why medical marijuana laws are
associated with a decline in
traffic fatalities.