Violent and property crime neither increased nor decreased permanently in Washington State and Colorado after legalization of recreational cannabis, according to a study conducted by Stockton University and two partners.
The only statistically significant change was a slight decline in burglary rates in Washington, according to the authors.
There were short-lived increases in property crime rates in Colorado and Washington, and on aggravated assault rates in Washington, immediately following legalization. But the increases were not permanent shifts, researchers said.
“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,” said Stockton Assistant Professor of Criminal Justice Ruibin Lu, the first author on the paper.
“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.”
The study examined only changes in serious crime, so it does not address the effect of legalizing marijuana on other types of crime, such as those related to driving under the influence of cannabis.
Funded by a grant from the National Institute of Justice, the study was conducted by researchers at Washington State University and the University of Utah as well as Stockton.
It appears in Justice Quarterly, a publication of the Academy of Criminal Justice Sciences.
Previous studies have reported mixed and inconclusive results on how legalizing cannabis affects crime, according to researchers.
Researchers chose Colorado and Washington because they were the two earliest states to legalize growing, processing and selling cannabis commercially for recreational use.
Researchers compared monthly crime rates in Colorado and Washington to crime rates in 21 states that have not legalized marijuana use for recreational or broad medical purposes at the state level.
Crime rates came from the FBI’s Uniform Crime Report from 1999 to 2016 for agencies that reported complete data during this period.
The study calculated how violent and property crimes changed for Colorado and Washington after legalization and retail sale, and compared the changes to what happened in states that had not legalized marijuana.
“As the nationwide debate about legalization, the federal classification of cannabis under the Controlled Substances Act and the consequences of legalization for crime continues, it is essential to center that discussion on studies that use contextualized and robust research designs with as few limitations as possible,” said Dale W. Willits, assistant professor of criminal justice and criminology at Washington State University, who was one of the coauthors of the paper.
“This is but one study and legalization of marijuana is still relatively new, but by replicating our findings, policymakers can answer the question of how legalization affects crime.”
Eleven states and the District of Columbia have legalized recreational marijuana sales, and New Jersey legislators have been considering either legalizing it through law or putting a referendum on the ballot so voters can decide the issue.