The Vermont Legislature is considering legalizing marijuana for personal recreational use. As part of this process, legislators should study data from Colorado about driving under the influence of marijuana and motor vehicle accidents.
In November 2012, Colorado voters approved a referendum that legalized marijuana for recreational purposes for anyone aged 21 and older. Colorado established licensed marijuana retail stores, regulated cultivation operations, and permitted the manufacture and sale of marijuana edibles such as chocolate bars.
Since legalization, Coloradans use marijuana more than the national average, among all age groups. A 2013 survey showed that 10 percent of Coloradans over 25 called themselves marijuana users, 29 percent of 18-to-25-year-olds, and 11 percent of 12-to-17-year-olds. The comparable numbers for a national sample were 5 percent, 19 percent and 7 percent.
Legalization has been associated with higher marijuana usage in Colorado than in the nation, especially among younger people. The relationship may not be causal, however, since the demographics of Colorado may be associated with higher usage rates, regardless of the state’s policy.
The number of motor vehicle fatalities in Colorado declined from 2006 to 2011, from 535 annually to 447, due perhaps to safety-related improvements in vehicle manufacturing. Over the next four years, fatalities slowly increased, from 447 in 2011 to 488 in 2014.
Since 2006, the percentage of Colorado motor vehicle fatalities where drivers tested positive for marijuana has increased from 7 percent to 19 percent. Since legalization, those numbers were 15 percent in 2013 and 19 percent in 2014. While some of this increase is due to improvements in testing technology, the statistics demonstrate that legalization has been associated with an increase in fatal motor vehicle accidents where drivers were impaired by cannabis. Colorado estimates that 94 people were killed on that state’s roads in 2014 because of marijuana-impaired driving.
The practice of most police agencies in Colorado is that if a motorist is stopped for suspected impaired driving in a non-accident situation, an alcohol breath test will be administered. If the driver tests over the legal limit for alcohol, he or she will be charged with DUI, and no drug tests will be conducted. If the alcohol test is negative, the driver’s blood will be tested for impairment by marijuana or other drugs. Blood tests are normally administered following accidents.
In 2014, of all drivers in Colorado tested for drug impairment, 24 percent tested positive for marijuana, compared with 19 percent in 2012, the last year before legalization. Colorado’s standard for impaired driving due to THC (the active chemical in marijuana) is 5 nanograms or more per milliliter.
Several fatal accidents attributed to marijuana impairment received press coverage in Colorado in 2014. Perhaps the most notorious was a double-fatal collision where autopsies showed both drivers had over 5 ng/ml of THC in their blood.
The current prohibition approach to marijuana is not working. Other states will likely join Colorado, Washington, Oregon and Alaska in legalizing recreational use.
In setting policy in Vermont, legislators should think carefully about the Colorado data showing that legalization is associated with increased marijuana usage, especially among younger people, and this increased usage in turn results in more motor vehicle accidents and fatalities due to marijuana-impaired driving.
The Vermont Legislature should not legalize marijuana unless it simultaneously establishes a clear policy regarding cannabis-impaired driving, including both education and enforcement. If such a policy cannot be developed by the end of the session in May, delay is better than hasty action.
Schools, colleges, police and state’s attorneys must then implement the policy. Judges must show little lenience toward defendants charged with impaired driving. Having Vermonters injured or killed by drivers high on legal marijuana is completely unacceptable.
Eric L. Davis is professor emeritus of political science at Middlebury College.