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. Texas Gov. 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.