Legalizing Marijuana Leads To ‘Substantial Decrease’ In Intimate Partner Violence, Study Shows

A new analysis of violence between intimate partners concludes that legalizing marijuana for adult use “results in a substantial decrease in rates of intimate partner violence.”

The finding also indicate that recreational cannabis legalization “substantially impacts the relationship between heavy drinking” and intimate partner violence (IPV), possibly as the result of people substituting marijuana for alcohol.

Author Samantha Gene Baldwin, a Georgetown master of public policy student, wrote in the thesis that the findings are “surprising,” saying the links between recreational marijuana legalization (RML) and IPV “require careful consideration.”

“As marijuana use is a known risk factor for IPV and legalization of recreational marijuana typically increases usage, RML could be expected to increase rates of IPV,” Baldwin wrote, adding: “Reduced alcohol use could complicate this relationship if marijuana acts as a substitute to alcohol. As alcohol consumption is a greater risk factor for IPV than marijuana use, any reduction in alcohol consumption would lessen the impact of RML on IPV.”

The study drew on data from the Federal Bureau of Investigation’s (FBI) National Incident-Based Reporting System (NIBRS), which includes details of crimes that are reported to police. Baldwin used data from 2013–2019, deciding not to include data from the COVID-19 pandemic.

The analysis found that “legalization of recreational marijuana results in 56.6 fewer reported incidents of IPV per 100,000 people.”

“Legalization of recreational marijuana results in a substantial decrease in rates of intimate partner violence.”

“The results of this analysis show that RML actually reduces rates of IPV,” the paper says, “however, the reason for this unexpected result requires further study.”

Existing literature suggests that marijuana and substance use generally are correlated with higher rates of IPV, Baldwin wrote. One might thus expect legalization, which has been shown in some studies to increase cannabis use among legal-age adults, to increase rates of IPV. However, the fact that cannabis may serve as a replacement for alcohol—which has a far stronger association with IPV—means the net effect of legalizing marijuana was to lessen violence.

“The increased usage could be acting as a substitute for other substances that have a stronger impact on rates of IPV, like alcohol and illicit drugs,” the paper says. “Alternatively, marijuana use may be less of a risk factor for IPV than previously thought.”

The prohibition of marijuana historically may also have played a role in the trends, Baldwin pointed out, writing: “Because marijuana has been illegal for recreational use until the past decade, those who used it may have been more impulsive and more likely to engage in risky behaviors on average.”

Notably, one finding of the study was that in states without legal marijuana, IPV rates appeared to fall as the proportion of heavy drinkers in the state rose. “This means that states without legal recreational marijuana actually have lower rates of IPV as heavy drinking increases,” Baldwin wrote—specifically, “a one percentage point increase in the population that qualifies as heavy drinkers results in 5.6 fewer incidents of IPV.”

The study acknowledges that finding is “counter to prior research finding alcohol consumption to be a major risk factor for IPV.”

“In states with RML,” it continues, “the relationship is reversed.” In those states, every additional percentage point increase in the population of heavy drinkers led to eight additional incidents of IPV.

Additional research, Baldwin says in the thesis, should focus on the more granular trends within states as well as the impact of retail cannabis accessibility on violence. Studies should also “evaluate how different types of marijuana policies impact IPV,” the paper continues, noting the spectrum of policy approaches “as a range from fully illegal, decriminalization, [medical marijuana legalization], to RML.”

“The relationship between marijuana policy and IPV may be more nuanced than these results suggest,” it says. “Further study is needed to determine whether IPV is impacted by where a state falls in this policy range.”

Some past research has also indicated that domestic violence falls in response to marijuana legalization. A study in 2019, for example, found that states that reduced penalties for simple cannabis possession saw a notable decline in cases where domestic violence victims suffered serious injuries.

A 2021 study, meanwhile, found that reductions of crime generally after marijuana legalization was being significantly understated because the FBI data is inconsistent and comes from voluntary participation by local agencies.

In 2020, researchers looked at how adult-use marijuana legalization in Washington and Colorado affected crime rates in neighboring states, and the resulting study determined that passage of recreational cannabis laws may have actually reduced certain major crimes in nearby jurisdictions.

The previous year, a federally funded study found that legalizing marijuana has little to no impact on rates of violent or property crime. The policy change did seem connected to a long-term decline in burglaries in one state, however.

A 2018 study from the think tank RAND said county-level data from California suggested that there was “no relationship between county laws that legally permit dispensaries and reported violent crime,” the researchers wrote. What’s more, there was a “negative and significant relationship between dispensary allowances and property crime rates,” though it’s possible that’s the product of “pre-existing trends.”

That same year, researchers at Victoria University of Wellington and Harvard University found that medical marijuana laws essentially have a null effect of crime rates, with one big exception: A nearly 20 percent reduction in violent and property crimes in California following the legalization of medical cannabis there.

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Photo courtesy of Chris Wallis // Side Pocket Images.