Tracey Lampe stakes cannabis plants at a medical marijuana growing facility in Denver, Dec. 6, 2013.
Matthew Staver/New York Times/Redux

Study: Marijuana legalization doesn’t increase crime

Updated

Three months after Colorado residents legalized recreational marijuana with the passage of Amendment 64 in Nov. 2012, Sheriff Tom Allman of Mendocio County, Calif. – a haven for marijuana growers – warned that an onslaught of crime was headed toward Colorado.

“Thugs put on masks, they come to your house, they kick in your door. They point guns at you and say, ‘Give me your marijuana, give me your money,’” Allman told a Denver TV station in February. His state became the first to legalize marijuana for medical use in 1996; Colorado followed suit in 2000. 

But a new report contends that fourteen years later, even after Colorado legalized the sale of small amounts of marijuana for recreational use on Jan. 1 of this year, violent and property crime rates in the city are actually falling.

According to data from the Denver Police Department, violent crime (including homicide, sexual assault, robbery, and aggravated assault) fell by 6.9% in the first quarter of 2014, compared with the same period in 2013. Property crime (including burglary, larceny, auto theft, theft from motor vehicle and arson) dropped by 11.1%.

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A study looking at the legalization of medical marijuana nationwide, published late last month in the journal PLOS ONE, found that the trend holds: Not only does medical marijuana legalization not correlate with an uptick in crime, researchers from the University of Texas at Dallas argue it may actually reduce it.

Using statistics from the FBI’s Uniform Crime Report and controlling for variables like the unemployment and poverty rates; per capita income; age of residents; proportion of residents with college degree; number of police officers and prisoners; and even beer consumption, researchers analyzed data from all 50 states between 1990 and 2006. (California became the first state to legalize medical marijuana in 1996; in the decade that followed, 10 states followed suit. Today that number is up to 20 states, plus the District of Columbia.) They wrote: 

“The central finding gleaned from the present study was that MML (medical marijuana legalization) is not predictive of higher crime rates and may be related to reductions in rates of homicide and assault. Interestingly, robbery and burglary rates were unaffected by medicinal marijuana legislation, which runs counter to the claim that dispensaries and grow houses lead to an increase in victimization due to the opportunity structures linked to the amount of drugs and cash that are present.”

The study drew a link between marijuana and alcohol use, surmising that the legalization of pot could cause the number of alcohol-fueled crimes to decline.

“While it is important to remain cautious when interpreting these findings as evidence that MML reduces crime, these results do fall in line with recent evidence and they conform to the longstanding notion that marijuana legalization may lead to a reduction in alcohol use due to individuals substituting marijuana for alcohol. Given the relationship between alcohol and violent crime, it may turn out that substituting marijuana for alcohol leads to minor reductions in violent crimes that can be detected at the state level.”

The pro-legalization group Norml cited a 2002 study by David Boyum and Mark Kleiman arguing that regulating marijuana on the same terms as alcohol “would tend to reduce crime.”

As a growing number of states are moving to legalize the use and sale of both medical and recreational marijuana, public opinion has changed dramatically. A Gallup poll from October 2013 showed that for the first time, a majority of Americans favored legalizing marijuana. The 58% of respondents who said they were in favor of legalization last year represented nearly five times the number who said so the first time Gallup asked the question in 1969.  

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Study: Marijuana legalization doesn't increase crime

Updated