No one seriously believes anymore in the Reefer Madness depiction of marijuana use, in which this new-fangled devil weed transforms otherwise upstanding teenagers into murderous sociopaths. Even some otherwise staunch social conservatives (e.g. Rick Perry) are beginning to embrace some degree of decriminalization as a fair and necessary step toward a fair and rational criminal justice system.
Yet there is a lingering strain of thought that full or partial legalization will inevitably bring a corresponding increase in crime.
Not so, says UT Dallas criminology professor Robert Morris, the lead author of a just-published study of crime rates in states that have legalized medical marijuana.
"We're cautious about saying, 'Medical marijuana laws definitely reduce homicide.' That's not what we're saying," Morris told UTD's news service. "The main finding is that we found no increase in crime rates resulting from medical marijuana legalization. In fact, we found some evidence of decreasing rates of some types of violent crime, namely homicide and assault."
The study looked at 17 years of FBI crime data covering homicide, rape, robbery, assault, burglary, larceny, and auto theft. Controlling for everything from unemployment and average income to per-capita beer consumption, Morris and fellow researchers then examined crime trends pre- and post-legalization and compared them with data from the rest of the states, which continued to bar medical marijuana.
"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 study sayd. "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."
Even if legalizing medical marijuana doesn't in fact reduce crime, the study concludes that it does not cause it to increase. This, Morris notes, runs counter to arguments commonly trotted out by opponents of marijuana decriminalization and legalization, like the claim that weed is a gateway to harder drugs, and that dispensaries and growing operations make prime targets for armed robbers.
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