Legalization of Marijuana Does Not Increase Crime

Updated on April 8, 2019
David AZ Cohen PhD profile image

David Cohen has a PhD in clinical criminology and worked in forensic psychiatry for 28 years. He also suffers from chronic back pain.


Reefer Madness

A 1936 movie called Reefer Madness set out to warn Americans of dangers inherent in the use of “Marijuana: The burning weed with roots in hell”. The movie portrayed dangerous criminal behavior, mental instability and promiscuous sexual behavior in marijuana using teens. Harry J. Anslinger, the first commissioner of the Federal Bureau of Narcotics, warned that marijuana led to “insanity, criminality, and death" and he used his influence to successfully outlaw the use of marijuana in the USA..

The only serious opposition to Anslinger’s program came from then NYC mayor Fiorello La Guardia. In 1944, the La Guardia Commission published unequivocal findings regarding marijuana use in New York: “… The practice of smoking marihuana (spelling in original) does not lead to addiction in the medical sense of the word. … The use of marihuana does not lead to morphine or heroin or cocaine addiction and no effort is made to create a market for these narcotics by stimulating the practice of marihuana smoking. … Marihuana is not the determining factor in the commission of major crimes. … Juvenile delinquency is not associated with the practice of smoking marihuana. … The publicity concerning the catastrophic effects of marihuana smoking in New York City is unfounded”.

Unfortunately, no one took the commission’s report seriously.

In 1937, the Marijuana Tax Act effectively put an end to legal sale and possession of marijuana in the United States. The Act was repealed in 1970 but was replaced by the Comprehensive Drug Abuse Prevention and Control Act. There was no real change in Federal or State policy regarding marijuana use and the Federal government still spends millions of dollars on enforcing anti-marijuana laws..

Legalization Hasn't Changed Perception

California passed Proposition 215 in 1996 and became the first state to legalize marijuana for medical use. Today marijuana is “fully legal” in 10 states and in Washington DC, is legally available for medical purposes in 23 more states and is “fully illegal” in only 17 states (source).

Unfortunately, despite legalization in the states, the attitude of the Federal Government hasn’t changed since Anslinger’s day. In 2017, then US Attorney General Jeff Sessions claimed that legalization of marijuana was linked to an increase in violent crime. Popular authors like Alex Berenson are campaigning hard against marijuana use. In a recent article Berenson claimed: “Marijuana can cause paranoia and psychosis, and those conditions are closely linked to violence — it appears to lead to an increase in violent crime”.

Research Finds No Link Between Legalization and Crime

By nature I’m a skeptic, and prefer research over polemic. So I went to my favorite research tool, Google scholar, to check out the literature on the “legalization-crime link”. What I found was, basically, that Sessions and Berenson, like Anslinger before them, are vocal but uninformed ‘experts’ with an agenda. The facts don’t back up their claims. La Guardia was right.

One 2014 paper analyzed data from states which have legalized marijuana, published between 1990-2006 in the FBI’s Uniform Crime Reporting Program. The authors found that legalization was significantly related to reductions in homicide and assault, and had a small, non-significant link to reductions in other types of crime, including forcible rape. There was no evidence in the study of an increase in crime after legalization.

A review paper from 2016 found evidence for a “significant drop in rates of violent crime” associated with legalization of medical marijuana.

Data from Washington State, in which marijuana use is “totally legal” (as opposed to legal just for medical purposes) shows a similar trend. A 2017 paper looked at official Washington State crime statistics for the years 2010-2014 and found: “that the legalization of recreational marijuana caused a significant reduction of rapes and thefts”. Legalization was not related to changes in rates of other crimes. Legalization was also shown to reduce alcohol use, both ‘regular’ and binge drinking- which may partially account for the reduction in rape.

Not all the research links legalization to reduction in crime. Some shows that legalization has no effect on crime rates. For example, a 2017 paper published in the journal “Contemporary Drug Problems” found no relationship whatsoever between the legal status of marijuana (totally legal, legal for medical purposes, decriminalized or totally illegal) and crime rate. One glaring exception was the finding that decriminalization of marijuana was connected with a significant reduction in the crime of assault.

The authors emphasized:

The possibility that drug use could decrease inhibitions that could be tied to increased aggression… increase in aggressive response to conflict, increase paranoia leading to violent reactions… or a that a person experiencing frustration due to withdrawal from drugs could react violently was not supported by this research, since aggravated assault rates were significantly lower in states where marijuana has been decriminalized.

Another 2017 paper, Pithily titled: Joint Culpability, reported a similar conclusion:

...Even heavy medical marijuana use has a negligible effect on criminality ... Our results suggest that liberalization of marijuana laws is unlikely to result in the substantial social cost from a surge in crime that some politicians clearly fear

On the local level, two papers I looked at (from California and Colorado) reported that the presence of a legal marijuana dispensary in a given neighborhood is linked to a decrease in some types of crime in that neighborhood, most probably due to the increased surveillance and pedestrian traffic in the area. The reductions in crime were highly localized and didn’t “spill over” into adjacent areas.

To sum up: there is no evidence that legalization of marijuana increases crime. There is some, limited, evidence that decriminalization, partial or total legalization may trigger a decrease in some types of crime, particularly violent crime.

Legalization is Linked to Reduced Opioid Use

While legalization may have, only a minimal impact on most types of crime, it does have a significant impact on use and abuse of opioid pain killers such as oxycodone and Percocet. Opioids are among the most widely abused drugs in the US. The Center for Disease control warns of an “opioid epidemic”, responsible for 70,000 deaths in the US every year.

A 2017 study published in the journal Drug and alcohol dependence reported that legalization was significantly related to reductions in opioid pain killer related hospitalizations. Similarly, a recent Canadian study reported:

...increased regulated access to medical and recreational cannabis can result in a reduction in the use of and subsequent harms associated with opioids, alcohol, tobacco, and other substances.

Lastly, two recent articles in the Journal of the American Medical Association found that legalization was associated with a significant drop in the number of prescriptions for opioid pain killers. A third found a lower rate of deaths related to opioid use in states with medical marijuana laws than in states with no such laws. The authors of the third study also warned against attempts by others to mislead the public by publishing ambiguous data from poorly designed studies claiming to find detrimental effects of medical marijuana use.


My search of the recent scientific literature found nothing that Fiorello La Guardia and his commission didn’t know 75 years ago, and its a shame that no one listened to him back then:

  1. There is no evidence that decriminalization or any type of legalization (medical or total) of marijuana use is associated with an increase in violent or non-violent crime.
  2. There is some evidence that legalization is associated with a decrease in violent crime.
  3. There is evidence that neighborhoods with legal marijuana dispensaries have lower crime rates than neighborhoods which don’t.
  4. Legalization of marijuana is associated with a decrease in prescription of opioid pain killers, as well as opioid related hospitalization and death.
  5. Claims of the catastrophic detrimental effects of legalization are unfounded and therefore panic over legalization is unwarranted.

Bottom line: Total legalization of marijuana use, legalization for medical purposes and decriminalization of marijuana use do NOT increase crime. To claim otherwise is, at best, misleading.

As legalization becomes more prevalent in the US and elsewhere, ongoing and more extensive research will be able to tell us more about the beneficial effects of legalization in different areas of society.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2019 David A Cohen


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    Post Comment
    • Carol Morris profile image

      Carol Morris 

      18 months ago

      Very interesting article.

    • Angel Guzman profile image

      Angel Guzman 

      18 months ago from Joliet, Illinois

      Marijuana is a wonderful plant.


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