A report published this month by the Cato Institute has found no association between the legalization of recreational marijuana and certain adverse social effects. The report, “The Effect of State Marijuana Legalization: 2021 Update,” was published online by the libertarian-leaning think tank on February 2.

The report builds on an earlier review of research studying the effects of legalizing marijuana and cannabis in states that had enacted reforms prior to mid-2018. That report found that projected effects, both positive and negative, were in many cases overstated by advocates on both sides of the issue.

“At the time, our data showed that state‐​level legalization of marijuana had generally minor effects,” the authors of the report wrote. “One notable exception was the increase in state tax revenue from legalized marijuana sales; states with legal marijuana markets have collected millions of dollars in state tax revenues.”

This year’s update includes additional data from states included in the original report as well as information from states that have legalized cannabis for use by adults since the first one was published. 

“New data reinforce our earlier conclusions,” the authors state in the 2021 update.

Drug Use

The report examined the relationship recreational cannabis legalization has on the rates of use of marijuana and other substances. While an increase in the use of cannabis was seen in states that legalized marijuana, the increase was consistent with trends in place before reforms were enacted.

“Legalizing states display higher and increasing rates of use prevalence, but these patterns existed prior to legalization,” the report found.

Similarly, the authors found no association between legalizing recreational marijuana and the use of more dangerous substances such as cocaine.

“These data suggest no clear relationship between marijuana legalization and cocaine use. Although Oregon saw an upward trend in cocaine use after legalization, Massachusetts saw a downward trend,” they noted. “In other states, including Washington and Maine, cocaine use rates are consistent with nationwide trends.”

Road Safety

The report also examined the impact of the legalization of marijuana on road safety, noting that two hypotheses exist on the subject. One holds that legalization will lead to an increase in drivers impaired by cannabis resulting in a negative impact on safety. 

However, reform advocates maintain marijuana legalization is likely to lead to a decrease in drivers impaired by alcohol, reducing the overall danger. The authors of the report noted that the “relevant measure for public safety is the net effect” and cited research that found “no effect on traffic fatalities among legalizing states.”

Crime And Violence

The authors noted that advocates for and against recreational cannabis legalization have postulated that the change may have an effect on crime rates, with “proponents of marijuana legalization argue that legalization reduces crime by diverting marijuana production and sale from underground markets to legal venues.”

“At the same time, legalization may lower the burden on law enforcement to patrol for drug‐​related offenses, freeing up financial and personnel resources for law enforcement to address more severe crimes,” they continued.

While opponents of marijuana legalization have warned that increasing marijuana commerce with legalization could also benefit violent underground operators, the data reviewed by the report showed that “overall, violent crime has neither soared nor plummeted in the wake of marijuana legalization.”

The data regarding the effect of marijuana legalization on other factors including mental health and suicide were also mixed. The authors also noted that economic and demographic outcomes were not likely to see a significant impact from legalization, although governments could expect to see a substantial effect on their budgets.

“One area where marijuana legalization has a significant impact is through increasing state tax revenue,” they wrote.