A report published in July in the scholarly journal Police Quarterly finds that in two states with legal adult-use marijuana, statistical evidence shows that crime clearance rates (the percentages of reported crimes that are solved) have improved or held steady. In both states (Colorado and Washington), one stated goal of the voter initiatives that brought legalization was to improve the allocation of police resources, in particular on violent and property crimes. The report suggests that this goal is being reached.

The report analyzes data from Colorado and Washington. Both states legalized adult use in 2012. The study’s authors used data obtained from the FBI’s Uniform Crime Reports (UCR) program, which is a “nationwide, cooperative statistical effort of nearly 18,000 city, university and college, county, state, tribal, and federal law enforcement agencies voluntarily reporting data on crimes brought to their attention.” The program has a budget of over $8 billion and has been gathering crime statistics since 1930. The information that the UCR gathers is analyzed by “Criminologists, sociologists, legislators, municipal planners, the media, and other students of criminal justice use the data for varied research and planning purposes.”

David A. Makin, an assistant professor for the Department of Criminal Justice and Criminology at Washington State University, is the lead author of the study. He stated: “Our results show that legalization did not have a negative impact on clearance rates in Washington or Colorado. In fact, for specific crimes it showed a demonstrated, significant improvement on those clearance rates, specifically within the realm of property crime.”

The report concludes:

As we document here, prior to legalization, several crimes clearance rates were either flat or decreasing. However, in the post-legalization period, we see considerable improvement. We cannot offer with absolute certainty that these changes are entirely the result of marijuana legalization, though we are quite certain that legalization has not unduly hampered police performance, at least as measured by clearance rates. Moreover, in the absence of other compelling explanations, the current evidence suggests that legalization produced some demonstrable and persistent benefit in clearance rates, benefits we believe are associated with the marijuana legalization proponents’ prediction that legalization would positively influence police performance.

The report analyzed the data for violent crime in Colorado and Washington and found that clearance rates have been declining over the years. After legalization in Colorado, however, this decline leveled out, and in Washington clearance rates for violent crimes began to improve. This change did not take place in other states.

The clearance rates for property crimes improved as well. For example, in Washington the clearance rate for auto theft cases rose 5 percent. Burglary clearance rates “increased dramatically.” Unsurprisingly, when adult use became legal in Washington and Colorado, arrest rates for marijuana possession dropped significantly—by about 50 percent.

A Caveat

It should be noted that these statistics do not confirm the notion that with legalization, police departments started finding better things to do with their resources than arrest marijuana users. Statistics about clearance rates do not include surveys of police departments on their allocation of man-hours. Auto theft clearance rates could start to fall again, for example, if budget cuts that have nothing to do with marijuana or its legality lead to a reduction in auto theft investigators. Nevertheless, the report does offer evidence that with legalization, clearance rates for property crimes and violent crimes have either held steady or improved. And for everyone but criminals, improved clearance rates are a good thing.

What do you think? Will additional studies confirm that police departments in legal states are pulling investigators from drug enforcement to other crimes? Leave a comment below.

state marijuana laws