Despite all the progress being made in state after state, no one is surprised that the opponents of legalized cannabis aren’t backing down. One of the arguments being marshaled against the expansion of cannabis rights attempts to link legalization to increases in violent crime, particularly homicide.

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Some make what seems like a pretty compelling case. But that case often depends on what might be called a myopic view of a limited number of data points; when we pull the focus back to take in the larger context, there’s nothing remotely conclusive in the numbers.

As just one example, a recent opinion piece in The Hill – a highly respected political publication read by many members of Congress, among others – made an anti-legalization case that at first blush seems strong. Jason C. Johnson, president of the Law Enforcement Legal Defense Fund, concludes “The legalization of marijuana has not resulted in a reduction in crime, as we were told it would. The numbers show the results are quite the opposite.”

Johnson cites post-legalization increases in homicide rates in Denver, Seattle, and Washington D.C. as his primary (and really only) evidence, although he does provide some socially and economically plausible rationale about how legalization could lead to higher crime rates.

Crime Rates By The Numbers

crime rates in legal states Figure 1

We’ll start with the data these critics are focusing on: trends for homicide rates in Colorado, Washington, and the District of Columbia, the three early adopters of legalized marijuana. Figure 1 shows that, after declining for most of the 21st century, FBI-reported homicide rates have been trending upward since legalization in all three jurisdictions.

Anyone looking for a quick and damning conclusion, however, should note at least one red flag:  the homicide rate for the total U.S. began increasing at around the same time as it did in the three early adopter states.

violent crime rates in illegal states Figure 2

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Figure 2 illustrates this, along with similar patterns in four somewhat arbitrarily chosen non-legal states, Ohio, North Carolina, Texas, and Wisconsin. Something has clearly been going across the nation, not just in places where cannabis has been legalized, and that “something” got its toehold in 2014-2015.

And without further evidence, it’s simply not reasonable to attribute the situation in Colorado, Washington, and the District to a different cause than whatever is driving the national trend. (The patterns are very similar if we look at statistics for all violent crime instead of homicides.)

Some have argued that legalization-induced crime is spilling across state borders. For example, in 2014 Nebraska and Oklahoma sued Colorado, claiming that marijuana was flowing into their states and “placing stress on their criminal justice systems.” (The Supreme Court later declined to hear the case.) But Ohio, North Carolina, Texas and Wisconsin are a long way away from any places where recreational marijuana was legal in 2014, making spillover seem implausible as an explanation for their own rising homicide rates.

So just what might be going on? We certainly can’t give a definitive answer to a question that’s still being debated by academics, police departments, and others. But let’s take a look at just one possible explanation.

Public Responses To Police Brutality

Nationally, the long downtrend in rates of violent crime came to an end and turned upward in 2014. That was the year when social unrest boiled over after the well-publicized deaths of several African-American men at the hands of police, resulting in (among other consequences large and small) the so-called “legitimacy effect.”

Criminologists Tracy Sohoni of Old Dominion has studied the societal factors that influence crime rates. “When incidents of police violence don’t appear to be adequately investigated or addressed, this reduces feelings of legitimacy in the criminal justice system,” Sohoni told The Stash. “…research supports [the argument] that when people feel the criminal justice system lacks legitimacy they’re more likely to commit crimes.”

She concludes “…the fact that the criminal justice system is not doing more to assure the public that they are working to prevent such injustices from occurring may subsequently increase crime.”

crime rates in 30 states Figure 3

Is the legitimacy effect the reason for the increasing crime rates across the U.S.? Figure 3 provides some interesting perspective. It shows the top 30 states ranked by the increase in their murder rates between 2013 (the last year of the long downtrend nationally) and 2017 (since 2018 data is not yet available). Colorado, Washington, and the District of Columbia are in the middle of the pack, ranking 30th, 27th, and 25th respectively.

Examples of states in the top ten include Missouri, Maryland, Illinois, and Ohio – each of which has experienced significant tensions in their major cities connected with protests of police actions, further suggesting that the legitimacy effect has at least played a role.

This line of thinking may not be the explanation, but it’s a better explanation for widespread increases in homicides than cannabis laws in a handful of states. Still, this doesn’t mean we can conclude that legalization hasn’t contributed incrementally to crime rates in some states – but just as significantly, critics can’t conclude that legalization hasn’t had the opposite effect, providing some downward offset to crime rates that have increased due to other factors. Anyone who holds either viewpoint will have to look beyond simple correlations in small data sets for their evidence.