Driving/ DUID

Claim: Legalizing marijuana increases traffic fatalities or leads to more impaired driving-related fatalities.

Rebuttal: There are many reasons to doubt claims that legalization causes an increase in fatal crashes. Such claims confuse correlation with causation and involve cherry picking of data. Though some research has found a modest increase in traffic fatalities in Colorado and Washington post-legalization, those are only two of the 11 legalization states.

According to figures from the Fatality Analysis Reporting System, four of the eight states with before-and-after data available saw decreased rates of fatal car crashes following passage of legalization laws. These reduced crash rates were greater than the reduction seen on the national level over the same time period.

Meanwhile, a paper published by the National Bureau of Economic Research analyzed the rates of drivers found with THC in their systems after fatal car crashes from 2013 to 2016. The researchers then compared the patterns of THC-positive drivers in Colorado and Washington during that time period to those in other states. In a summary of their results, the authors write, “We find the synthetic control groups saw similar changes in marijuana related, alcohol-related and overall traffic fatality rates despite not legalizing recreational marijuana.”

Reports and data cited by the opposition are misleading. For example, an AAA study claims, “Fatal crashes involving drivers who recently used marijuana doubled in Washington after the state legalized the drug.” Yet, the statistics were for prevalence data only, meaning the evidence does not show marijuana use caused the crashes. Further, the state laboratory identified THC in the drivers’ blood that was categorized as “recent-use.”  THC can stay in one’s system for up to seven days or more since marijuana was last used, so a positive test does not mean the person used cannabis recently or was impaired.  Finally, both Colorado and Washington collected only partial data prior to legalization, meaning any before-and-after comparisons are misleading.

Teen Use

Claim: Legalizing, taxing, and regulating marijuana will lead to an increase in youth cannabis use.

Rebuttal: This claim is simply not borne out in the data. Colorado and Washington have both conducted large-scale surveys with thousands of high school students since both states legalized adult-use cannabis in 2012. The results have shown modest decreases in rates of youth cannabis use.

Prohibition has done nothing to stop youth from accessing cannabis; this is because unlike licensed businesses, drug dealers do not check ID. Regulating the cannabis market would require businesses to check ID for proof of age. Regulating marijuana sends the message to youth that marijuana is for adults.


Claim: Regulating marijuana will increase crime/states that have legalized have seen an increase in violent crime.

Rebuttal: In a 2018 study, scientists found “no statistically significant long-term effects of recreational cannabis laws or the initiation of retail sales on violent or property crime rates.” In a recent paper using regression analysis, a University of Washington researcher wrote, “Results indicate that the legalization of marijuana, both recreational and medical, does not increase violent crime rates. In contrast, marijuana legalization could lead to a decline in violent crime such as homicide, robbery and aggravated assault.” 

Meanwhile, legalizing marijuana also frees up police time for crimes with victims. In a 2018 analysis, experts at Washington State University found that police solved significantly more violent and property crimes after passage of legalization laws in Colorado and Washington.  

Virtually all crime associated with marijuana is a result of its prohibition. Prohibition exposes consumers to an illicit criminal market and more harmful drugs. Both buyers and sellers are vulnerable to violence due to the underground nature of the sales and an inability to settle disputes through the legal system. Criminal actors often use violence to expand their turf. Proposals to legalize marijuana for adults create tightly regulated systems, where cannabis will be sold by legitimate taxpaying businesses instead of drug dealers.


Claim: Marijuana use causes schizophrenia.

Rebuttal: Many opponents misrepresent a 2017 report by the National Academies of Sciences, Engineering, and Medicine, which found an association between cannabis use and schizophrenia, not that cannabis use causes schizophrenia. In fact, the report itself noted, “In certain societies, the incidence of schizophrenia has remained stable over the past 50 years despite the introduction of cannabis into those settings.” Surely if marijuana use caused schizophrenia, that would not be the case.

Further, one of the committee members of the study, Ziva Cooper, rebutted the claim that marijuana use causes schizophrenia in a series of Tweets. Cooper wrote,

“Since the report, we now know that genetic risk for schizophrenia predicts cannabis use, shedding some light on the potential direction of the association between cannabis use and schizophrenia.”

Consumers should be educated on the potential risks of cannabis, and legalization and regulation legislation provides for labeling to include a warning on the potential harms.


Claim: Today’s marijuana is stronger than the marijuana from years ago; Colorado has seen an increase in ER visits due to potent cannabis.

Rebuttal: Regulating cannabis will ensure that the consumer will know exactly what they are getting and how much of it. Servings will be limited to 10 mg of THC per serving, and strict labeling requirements provide that labels on cannabis products include a warning on how long the product takes to take effect. None of these protections exist in the illegal market. 

Even the most potent marijuana is far less harmful than alcohol. The CDC attributes about 40,000 deaths per year to alcohol use alone, including hundreds of overdoses. It attributes zero to marijuana, and there has never been a fatal marijuana overdose. Adults should not be punished for making the safer choice.


Claim: Marijuana is a gateway to the use of more harmful and addictive drugs.

Rebuttal: Marijuana is less addictive than alcohol and tobacco, and the “gateway theory” has been debunked repeatedly. Most recently, in 2017 the National Academies of Sciences, Engineering, and Medicine reported that there is no substantial link between marijuana use and the use of other illegal drugs. And, the vast majority of people who have used marijuana never try any other drugs.

In contrast, the illicit market can be a gateway. Many people who sell cannabis illegally also sell other drugs, and in some cases cannabis is even laced. Some individuals who never would have chosen to use PCP, cocaine, and opiates are exposed to them because cannabis has been driven underground where they have no idea what they’re getting. Only legalization and regulation allows cannabis consumers to know what they’re getting.

$4.50 study

Claim: “For every dollar gained in tax revenue, Coloradans spend approximately $4.50 to mitigate the effects of legalization.”

Rebuttal: This study has been widely lambasted as junk science. The bulk of the study’s cited costs of legalization in Colorado result from a supposed increase in dropout rates. In reality, teens’ cannabis use hasn’t increased, and graduation rates are up.

The Illinois Economic Policy Institute and the Project for Middle Class rightly urged lawmakers to reject those “dubious claims” because the report suffers from “poor policy analysis.” It noted, “Because the authors fail to attempt to isolate the impact, no peer-reviewed academic journal would consider the findings credible.”

The illicit market won’t go away

Rebuttal: While it will not happen overnight, within a few years of implementation of a state marijuana regulation law, intrastate demand should be fully satisfied by the regulated market, if enough supply and outlets are allowed. The Colorado Marijuana Enforcement Division’s Market Size Demand for Marijuana in Colorado Market 2017 Update reported that, “Colorado’s preexisting illicit marijuana market for residents and visitors has been fully absorbed into the regulated market.”

However, as long as dozens of U.S. states maintain prohibition, their demand will be served by illegal production somewhere. Colorado, Oregon, and California have long been sources of cannabis exported to other states, and there is no reason to expect that to stop until other states have their own legal supplies.

Developing brains of young adults (under 25)

Claim: Cannabis should not be allowed for adults under 25 because they still have developing minds.

Rebuttal: Marijuana regulation can and should include education about the risks related to cannabis, including any risks specific to younger cannabis consumers. That said, it’s worth noting that the alarming claims related to cognitive function for young adults have been exaggerated. A systemic review of scientific literature that was published in JAMA Psychiatry found cannabis exposure in adolescents and young adults is not associated with any significant long-term detrimental effects on cognitive performance.

It is also worth noting that teen marijuana use has not increased in adult-use states, and that adults between the ages of 21 and 25 are allowed to use alcohol, which causes severe adverse effects on the brain and — unlike cannabis — can cause fatal overdoses. If younger adults are allowed to make their own decisions about this far more dangerous substance, they should also be allowed to decide whether to use cannabis.

Legalization is bad for minority communities

Claim: Legalization is bad for minorities because there are still disparities in arrests.

Rebuttal: Unfortunately, racially unequal policing has not ended with legalization, and disparities in marijuana arrests have persisted in states that legalized. There needs to be a comprehensive effort to address disparities in all types of law enforcement, and we should do all we can to eliminate the inequities both in cannabis and elsewhere. While disparities have not disappeared, it is important to note that the total number of people arrested, and the total number of black and Latino people arrested, has dropped considerably after legalization in Colorado and Washington. For example, from 2012 to 2017, marijuana arrests declined significantly in Denver, including reductions of 64% and 89% in the arrests of Hispanic and black residents, respectively.

In addition, the Stanford Open Policing Project found that both the total number of searches during traffic stops and racial disparities for those searches have dropped significantly in Colorado and Washington post-legalization. Unwarranted searches can be intrusive, humiliating, and dangerous, particularly for people of color. 

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MPP Rebuttals to Opposition.pdf 49