Is Cannabis A Crime Fighter?

A new paper finds no evidence that medical marijuana leads to more crime:

[T]hese findings run counter to arguments suggesting the legalization of marijuana for medical purposes poses a danger to public health in terms of exposure to violent crime and property crimes. To be sure, medical marijuana laws were not found to have a crime exacerbating effect on any of the seven crime types. On the contrary, our findings indicated that [medical marijuana legalization (MML)] precedes a reduction in homicide and assault. While it is important to remain cautious when interpreting these findings as evidence that MML reduces crime, these results do fall in line with recent evidence and they conform to the longstanding notion that marijuana legalization may lead to a reduction in alcohol use due to individuals substituting marijuana for alcohol. Given the relationship between alcohol and violent crime, it may turn out that substituting marijuana for alcohol leads to minor reductions in violent crimes that can be detected at the state level. That said, it also remains possible that these associations are statistical artifacts

Emily Badger explains the study’s methodology:

Researchers at the University of Texas at Dallas looked at the FBI’s Uniform Crime Report data across the country between 1990 and 2006, a span during which 11 states legalized medical marijuana. Throughout this time period, crime was broadly falling throughout the United States. But a closer look at the differences between these states – and within the states that legalized the drug before and after the law’s passage – further shows no noticeable local uptick among a whole suite of crimes: homicide, rape, robbery, assault, burglary, larceny, and auto theft.

Sullum adds:

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.