Drug Legalization

Study Finds Marijuana Legalization Had Little Impact on Crime in Colorado or Washington

A comparison with other states finds "no statistically significant long-term effects" on violent or property crime rates.


Last night I debated drug policy at the Soho Forum with Alex Berenson, who claims in his book Tell Your Children that marijuana legalization caused "sharp increases in murders and aggravated assaults" in Colorado and Washington. There were already several reasons to question that claim, and a study published today in Justice Quarterly casts further doubt on it, finding "no statistically significant long-term effects of recreational cannabis laws or the initiation of retail sales on violent or property crime rates in these states."

Ruibin Lu, an assistant professor of criminal justice at Stockton University, and nine collaborators compared monthly crime rates in Colorado and Washington to monthly crime rates in "the 21 states that have not legalized marijuana use for recreational or medical purposes on a large scale." Based on FBI data for 1999 through 2016, they considered what happened after legalization was approved in 2012 and after state-licensed sales to recreational consumers began in 2014. "In general," they report, "the results suggest that marijuana policies and laws have had little effect on crime in Colorado or Washington State."

While both states saw statistically significant increases in property crime immediately after legalization, those changes were short-lived. Compared to the control states, violent crime rose slightly in Colorado and Washington after legalization, but the differences were not statistically significant. After retail sales began, violent crime rates remained essentially the same in both states. That's a far cry from the "sharp increases in murders and aggravated assaults" reported by Berenson.

Although Lu et al. do not separately report homicide rates, their tables show that, compared to the control states, Colorado saw a slight drop in aggravated assaults after legalization and a slight increase after retail sales started. In Washington, there was a slight increase after legalization and essentially no change after the state's pot shops opened. Except for the small post-legalization increase in Washington, none of these differences was statistically significant.

"Our results suggest that there may have been some immediate increases in crime at the point of legalization," Lu et al. say, "yet there have been essentially no long-term shifts in crime rates because of legalization, aside from a decline in burglary in Washington. Though the short-term increases might appear to suggest that marijuana increased crime, we caution against this interpretation as the increases do not reflect permanent shifts (that is, these are shifts in intercepts, not slopes) and could be artificially induced by the small number of time units between legalization and sales…. Following legalization and the start of retail sales (2014), Colorado and Washington follow the same basic pattern as the control states, suggesting that legalization did not result in any major increases or decreases in crime."

Lu et al. caution against drawing conclusions based on simple before-and-after comparisons that do not take into account pre-existing trends or crime rates in states that have not legalized marijuana. "Many politicians are inclined to make use of the earliest available data, and unfortunately too often what is available for public consumption at the outset of change in policy represents research employing limited pre/post analyses or misrepresentation of facts," they write. "A lack of robust research studies and overreliance on limited pre-post analysis perpetuate a state of confusion concerning to what extent legalization influences crime."

Although their study includes just four years of post-legalization data, Lu and her colleagues sought to address the shortcomings of prior analyses by using a more rigorous methodology. "Our results are robust in that we examined the first two states to legalize marijuana and compared them to states with no marijuana laws at all," they write. "Moreover, we estimated our models in a variety of manners, including models with different interruption points, single-group interrupted time series analyses, and as a set of pooled cross-sectional models. None of our models revealed long-term effects of marijuana legalization on serious crime rates."

Berenson argues that marijuana causes psychosis, which leads to violent crime. "The black tide of psychosis and the red tide of violence are rising together on a green wave," he warns in his book. So far the evidence from Colorado and Washington, the first states to legalize marijuana for recreational use, does not seem to support that description.

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  1. I always found the claims that drugs cause people to steal to support their habit to be curious. There are a million stories out there of people whose family members became degenerate drug addicts. And while most of them involve the person stealing from family members or lying to friends and family to obtain money for drugs, they almost never involve the person becoming a professional criminal to support their habit.

    Are people who break into homes and steal cars and such sometimes drug addicts? Sure. But, in most if not all cases they are examples of criminals who also happen to use drugs not otherwise law abiding people who became criminals to feed their habits.

    The idea that drugs cause people to become criminals comes mostly from criminals giving drugs as an excuse for doing what they would have done anyway.

    1. I think car prowling is probably caused in some part by desperate junkies who might not otherwise commit crime, but otherwise agree.

      1. Petty theft and ripping off friends and family is definitely junkie behavior. I think John is probably right that it doesn’t often lead people to being serious criminals.

    2. For pot hell no, for opiates and stimulants? Prohibition causes prices to be so high it absolutely does cause property crime. I’ve never known any addict, besides ones with enough income it wasn’t an issue, that wasn’t engaging in burglary, car hopping, shoplifting, various frauds, etc. Not one of them did any of that when sober.

      1. Such interesting friends you have.

  2. “no statistically significant long-term effects of recreational cannabis laws or the initiation of retail sales on violent or property crime rates in these states.”

    Criminal use of cannabis, however, dropped to nearly zero.

    1. ^ think about this!^

  3. “The black tide of psychosis and the red tide of violence are rising together on a green wave,” he warns in his book

    , a brown squirt.

    1. the brown tide of bullshit and the red tide of bloody lies…

    2. I strongly suspect social pressure is the only thing that stops Reefer Madness Berenson from also complaining about how pot makes innocent white girls have crazy sex with those coloreds in the jazz clubs.

  4. “Last night I debated…”
    “…a study published today in…”

  5. “The black tide of psychosis and the red tide of violence are rising together on a green wave,”

    Clean out your locker at the club, Bob, because you’re fscking fired.

  6. What crimes replaced the arrests for possession of marijuana?

  7. Wait wait wait. Are you telling me that people who smoke pot are too high to do anything but eat nachos and watch Netflix? How much did this study cost, and how do I set up one to verify the results?
    Oh, and FIRST, botches!

  8. Thanks for taking your time to write this. tree service

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