A new study published by Justice Quarterly suggests that recreational marijuana legalization did not have a statistically significant impact on violent and property crime rates in Colorado and Washington. The study, titled “The Cannabis Effect on Crime: Time-Series Analysis of Crime in Colorado and Washington State,” was conducted by researchers from Washington State University, Stockton University, and the University of Utah.

The researchers compared pre- and post- legalization crime rates in those two states with the crime rates in 21 states “that have not legalized marijuana use for recreational or medical purposes on a large scale.” They found that there was an immediate increase in property crime rates in both states, and aggravated assault rates in Washington, but those changes did not persist. The researchers claim that their study used more rigorous criteria then previous research; “[g]iven the likelihood of more states legalizing recreational marijuana, we felt it was important to apply robust empirical methods to parse out the effects of this action on crime in the first years after legalization” said Ruibin Lu, assistant professor of criminal justice at Stockton University.

Pro-marijuana advocates should and will rely on studies like this (and this) as they continue to press the case for broader legalization and acceptance of marijuana. Legalization opponents will likely counter that legalization was supposed to decrease crime rates by moving marijuana sales into the mainstream, and this study should actually dampen the push for legalization. One study will not put that debate to rest, but this is another data point to consider. We will keep you updated on other data points as they arise right here on our blog.