The Problem of “Driving while Stoned” Demands an Aggressive Public Policy Response
Authors: Larkin Paul J. 
Published: November 2018

Mark A.R. Kleiman and his colleagues (hereafter Kleiman) have done the public a service by highlighting the problem of “driving while stoned.” Drug-impaired driving is a serious national problem. Numerous drugs other than alcohol, whether legal or illegal—such as opioids, cocaine, tranquilizers, sleep aids, hallucinogens, and marijuana—degrade driving performance and increase the risk of highway morbidity and mortality. Other than alcohol, marijuana is the biggest problem because it is the most commonly used drug, and its use is increasing, given marijuana legalization. Two facts aggravate that problem: (1) marijuana is often combined with alcohol and (2) a marijuana-alcohol cocktail has an enhanced debilitating effect on safe motor vehicle handling. As the U.S. Office of National Drug Control Policy has noted, driving while impaired is a major public health problem. Kleiman is correct that identifying impairment attributable to substances other than alcohol is a difficult problem. Two twentieth century developments helped society reduce the number of alcohol-related crashes, injuries, and deaths: the passage of 0.08 g/dL blood-alcohol content laws, and the development of reliable, easily operated, hand-held Breathalyzers for roadside use. Unfortunately, we cannot successfully use that approach for impairing drugs other than alcohol. We do not know what amount of THC impairs a majority of drivers. In any event, we do not have a measurement device comparable to a Breathalyzer. Kleiman argues that, given those enforcement problems, we should use only administrative measures to penalize marijuana-impaired driving. I think that there is room for the criminal justice system. People who use marijuana and drive put others at risk of injury or death. Just as legislatures can force a factory to bear the risk of pollution-related injury, so too can a legislature force marijuana users to internalize any costs of their drug use. If you use marijuana, don’t drive for at least eight hours. Use public transportation. Take a cab. Call Uber. Walk. Ask a friend for a lift. Or just remain where you are. No one has a constitutional right to drink alcohol, to smoke marijuana, or to drive an automobile. Society hardly asks too much of its citizens to demand that they not do all three simultaneously or to delay driving for eight hours after either of the first two activities. That is not all. States should test every driver involved in a crash, particularly one involving a fatality, not only for alcohol but also for legal and illegal impairing drugs. Moreover, all 50 states fix 21 as the minimum drinking age and the minimum age for recreational marijuana use. Whatever administrative penalty the states impose for underage drinking and driving—such as license suspension—should apply as well to everyone under that age who tests positive for any illegal drug use. States should also report on a regular basis the data regarding motorists’ use of impairing drugs, including marijuana. There is also room for Congress to act. Because U.S. highways are arteries of interstate commerce, Congress can protect their use by commercial and non-commercial drivers alike by preventing interstate highways from being used by drivers who increase the morbidity and mortality risks of others. Congress can demand that the states use a portion of their federal highways funds to adopt safety or information-gathering measures like the ones suggested above. At a minimum, Congress should force states to fund the cost of learning what their marijuana legalization measures have wrought.