It is currently illegal to drive while impaired by cannabis in every state, and it remains illegal after cannabis is legalized. Many legalization laws include funding to increase the number of officers with Drug Recognition Expert (DRE) training to improve detection of drivers impaired by prescriptions, over-the-counter medicines, cannabis, and illicit drugs. One of the 12 steps of a DRE analysis is a fluids test to determine whether a driver has consumed cannabis or another substance. Cannabis can stay in one’s system for 30 days after last-use so this piece of evidence is considered alongside all other evidence (such as the smell of recently burnt cannabis, behavior indicating impaired driving, and field sobriety results) to determine if the driver was impaired.

Reassuringly, data from the Fatality Analysis Reporting System shows four of the eight states that legalized cannabis from 2012 through 2016 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 within the same time period.

Cannabis prohibition has failed miserably at keeping cannabis out of the hands of teens. From 1975-2012, 80-90% of 12th graders consistently reported that cannabis was “fairly easy” or “very easy” to obtain. For the first time since the survey began 40 years ago, high school seniors’ perception of cannabis’s availability has dipped below 80% — after states began to legalize cannabis. As the head of the federal National Institute on Drug Abuse (NIDA), Nora Volkow, testified in the U.S. Senate in March of 2021, “Specifically in the United States, legalization by some states of marijuana has not been associated with an increase in adolescents’ marijuana use.” This is unsurprising since illicit cannabis sellers have no incentive to ask for ID, while licensed businesses have a huge incentive to do so.

Like alcohol Prohibition before it, cannabis prohibition puts buyers and sellers at risk of violence. There are numerous tragic examples of cannabis-related armed robberies resulting in death, violence being used to solve cannabis-related disputes, and even of police informants being discovered and murdered. Legalizing cannabis reduces the inherent risk in an underground product. 

At the population-wide level, a 2018 study found “no statistically significant long-term effects of recreational cannabis laws or the initiation of retail sales on violent or property crime rates.” Similarly, 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.” 

Regulating cannabis will ensure the consumer knows exactly what they are getting and how much. Servings are generally limited to 10 milligrams of THC, and strict labeling requirements provide that labels on cannabis products include a warning on how long the product has to take effect. None of these protections exist in the illegal market. 

Cannabis is far 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 cannabis use and the use of other illegal drugs. The vast majority of people who have used cannabis never try any other drugs.

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, the cannabis use for teens has not increased, and graduation rates are up.

Cannabis regulation can and should include education about the risks related to cannabis, including risks specific to younger adults. That said, 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. Alcohol is far more dangerous to the brain and the entire body than cannabis, and it is legal for adults 21 and older. More than 2,000 Americans die every year from acute alcohol intoxication, whereas cannabis has not been shown to cause overdoses. Adults who are of legal age to drink alcohol should be allowed to choose the less damaging substance.

While it will not happen overnight, within a few years of full implementation of a state cannabis 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.” 

In most cases where there is still significant illicit market activity after legalization, it is generally in municipalities that have banned stores or is for export to the many states that still prohibit cannabis. In other words, in mature legalization markets, the vast majority of illegal activity is due to the continuation of prohibition, not due to legalization. Excessive taxes and regulations can also make legal cannabis uncompetitive and cause the illicit market to persist.