Legal cannabis has little effect on crime rates, according to a study authored by Stockton University criminal justice assistant professor Ruibin Lu.
Along with researchers at Washington State University and the University of Utah, Lu studied the effects of adult use cannabis legalization on crime in Washington and Colorado and found no statistically significant long-term effects of the laws, save for one exception: a decline of burglary rates in Washington.
Together the team compared monthly crime rates in the two states to those in 21 states without a legal medical or adult use market. Using the FBI’s Uniform Crime Report from 1999 to 2016, they calculated how both violent and property crime changes from before legalization and retail sale to after, and compared those changes to what happened in states without a cannabis market.
The study suggests that cannabis legalization and sales have had minimal or no effect on major crime.
The researchers published their findings in Justice Quarterly, a publication of the Academy of Criminal Justice Sciences.
“In many ways, the legalization of cannabis constitutes a grand ongoing experiment into how a major public policy initiative does or does not accomplish its expected outcomes,” Lu wrote in the study. “Given 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.”
Thus far, 11 states and the District of Columbia have legalized adult use cannabis.
The study chronicled some immediate increases in crime immediately following legalization. Property crime rates in Colorado and Washington both increased, and aggravated assault rates rose in Washington. In both states, increases were short lived and did not result in long-term shifts.
The study notes that because it focused on serious crime, it does not address legalization’s effect on other types of crime, such as driving under the influence of cannabis. The researchers also note that they cannot rule out the possibility that cannabis legalization laws may have different effects on different communities.