A new report says drivers are nearly as likely to be high on pot or pills as drunk on alcohol, and it urges states to take steps to better monitor and control drugged driving.
The report, “Drug-Impaired Driving: A Guide for What States Can Do,” cites crash data and surveys chronicling a steady increase in driving under the influence of drugs, even as drunken driving rates continue to fall.
“I don’t think drugged driving has received nearly the attention that drunk driving has received,” said the author, James Hedlund, a retired executive with the federal National Highway and Traffic Safety Administration who has studied and written extensively on highway safety.
The report was issued today by the Governors Highway Safety Association, a nonprofit organization based in Washington, D.C.
Using the most recent available data from fatal crashes, it said nearly 40 percent of the victims who were tested had drugs in their system, with about one-third testing positive for marijuana. But it cautioned that the data has limitations, including no distinction between THC, the marijuana component that causes impairment, and metabolites that remain in a person’s system long after the effects of smoking pot have worn off.
As debate intensifies about whether marijuana, now legal in some form in nearly half of the states, causes an increased crash risk for drivers, better data is needed, Mr. Hedlund said.
“The jury is still very much out,” he said. “You certainly could not say unambiguously that marijuana increases crash risk. The only thing you can say with confidence is that in laboratory experiments, it affects a lot of things that are related to driving.”
A research paper by NHTSA in February said “there is evidence that marijuana use impairs psychomotor skills, divided attention, lane tracking and cognitive functions. However, its role in contributing to the occurrence of crashes remains less clear.”
While measurement of alcohol impairment is clearly established, with all states classifying an 0.08 blood alcohol level as the threshold of intoxication, there is no similar standard for what constitutes impairment from marijuana, Mr. Hedlund said. Some states, including Pennsylvania, have what amounts to “zero tolerance” laws, while others have established largely arbitrary thresholds for THC levels.
The report recommends better public education, noting that most drivers in surveys have said they don’t believe marijuana impairs their driving, while some said it improves their performance behind the wheel.
While police officers routinely are trained in detecting alcohol intoxication, relatively few are schooled in recognizing impairment from marijuana, prescription medicines, illegal narcotics or over-the-counter medications, it said.