New Study Links Marijuana Legalization to Better Police Effectiveness

The research found that clearance rates significantly increased after recreational marijuana was legalized.

Police effectiveness for certain crimes improves after marijuana is legalized, suggests the findings of a new study published in the journal Police Quarterly.

Researchers from Washington State University used data from Colorado and Washington to examine the effects of marijuana legalization on public health and safety. In 2012, Colorado and Washington became the first two states to make marijuana legal for adults aged 21 and older.

The researchers found that police clearance rates — the number of cases solved — for violent and property crimes improved significantly in the two states after recreational marijuana was legalized. Throughout the rest of the nation, according to FBI data from 2010 through 2015, clearance rates remained essentially unchanged.

“Our results show that legalization did not have a negative impact on clearance rates in Washington or Colorado,” said David Makin, researcher on the study and assistant professor in WSU’s Department of Criminal Justice and Criminology “In fact, for specific crimes it showed a demonstrated, significant improvement on those clearance rates, specifically within the realm of property crime.”

Prior to legal marijuana sales being authorized, clearance rates for the two crimes in Colorado and Washington had been falling; meaning police effectiveness had been dropping. Makin said that the act of legalization provided the unique opportunity to investigate the impact cannabis prohibition had been having on public health and safety.

“If you think about our history, it’s rare where you have something that is entirely illegal that then becomes legal,” said Makin. “And we have an opportune moment to study to what extent that particular change had on society.”

The findings back the common argument by advocates of cannabis legalization that ending prohibition allows for police resources to be allocated to more serious crimes.

In summary, the study from Washington State researchers found that after marijuana was legalized:

  • The number of marijuana possession rates plummeted in both states. In Colorado, they dropped nearly 50 percent. In Washington, arrest rates for possession dropped more than 50 percent.
  • Clearance rates for violent crimes increased.
  • Clearance rates for burglary and motor vehicle theft “increased dramatically.”
  • Property crime clearance rates increased.

“It demonstrates just how critical these types of policy changes can be,” Makin said. “I would offer it truly demonstrates why we need empirical data to support these types of studies, so we can understand to what extent crime and communities are influenced as more and more states move to legalization.”

Makin acknowledged that while he and his colleagues found a correlation between marijuana legalization and police effectiveness, it does not necessarily mean that improvements in clearance rates were not exclusively related to the change in cannabis policy. Other factors, such as new law enforcement strategies, or greater allocated resources, could have also made an influence.

The full text of the study, “Marijuana Legalization and Crime Clearance Rates: Testing Proponent Assertions in Colorado and Washington State,” is available through SAGE Journals.

police stance on marijuana

Impact of Marijuana Legalization on Law Enforcement

While marijuana remains illegal under U.S. federal law, nine states have legalized recreational marijuana and 30 have passed comprehensive medical marijuana laws.

With three-fifths of U.S. states now legalizing marijuana in some capacity, researchers have been able to examine its impacts on public health and safety. So far, those findings have been positive. The overall crime rate and traffic fatalities have decreased in Colorado since the adult use marijuana law took effect. Drops in violent crime have also occurred in Washington after marijuana was legalized.

Nearly 7 in 10 Americans now favor adult use marijuana legalization, and a majority feels that the costs associated with enforcing marijuana prohibition are higher than the benefit they provide.

A majority of American police officers are also in favor of marijuana legalization to some degree, with some law enforcement officials arguing that it would free up police to concentrate on issues more important to the average citizen.

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