Medical marijuana legalization may lead to lower homicide rates, study finds
During the debate over regulating medical marijuana dispensaries, opponents frequently suggested that the presence of such shops would cause crime to rise. Numerous studies have debunked these predictions and a new University of Texas Dallas inquiry does, too -- but with a twist. Researchers note that crime rates related to some of the most serious offenses, including homicide, actually fell in states after medical marijuana was legalized, although they stop short of making a definitive causal connection.
"The Effect of Medical Marijuana Laws on Crime: Evidence from State Panel Data, 1990-2006," credited to Robert G. Morris, Michael TenEyck, J. C. Barnes and Tomislav V. Kovandzic, appears in the journal PLOS ONE. We've included the complete article below, but an abstract summarizes the findings like so: "Results did not indicate a crime exacerbating effect of MML [medical marijuana legalization] on any of the Part I offenses. Alternatively, state MML may be correlated with a reduction in homicide and assault rates, net of other covariates."
The italicized "may" above appears in the original -- and the word appears again in a passage that drills a bit deeper into the results. Here's an excerpt:
With one exception -- forcible rape -- states passing MML laws experienced reductions in crime and the rate of reduction appears to be steeper for states passing MML laws as compared to others for several crimes such as homicide, robbery, and aggravated assault. The raw number of homicides, robberies, and aggravated assaults also appear to be lower for states passing MML as compared to other states, especially from 1998-2006. These preliminary results suggest MML may have a crime-reducing effect, but recall that these are unconditional averages, meaning that the impact of the covariates and other factors related to time series trends have not been accounted for in these figures.Also included in the piece are a series of graphics depicting the rates of assorted crimes in medical marijuana states. As you can see, the rates for homicide, robbery, aggravated assault and burglary are all down over the test period. In contrast, those related to forcible rape, larceny and auto theft remain above the "prior to medical marijuana" line, although generally not by a huge margin.
This study joins others that have documented little to no negative societal impact related to medical marijuana. In February, for instance, our William Breathes detailed University of Colorado Denver research showing that "a medical marijuana dispensary in the Denver area doesn't have any more impact on its neighborhood than does a coffee shop or a drugstore."
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