Effective Drugged-Driving Laws Elusive As Marijuana Legalization Spreads

DruggedDriver_final_3.2.jpg illustration by Paul Dolan; 4774344sean./iStock/Thinkstock

CARS.COM — With four states and the District of Columbia already having legalized the recreational use of marijuana and 20 more reportedly considering it this year researchers and legislators alike are finding public-safety issues as cloudy as ever. According to a study by travel-services giant AAA, the presence of THC, the active chemical component in marijuana, in the systems of motorists involved in fatal crashes is spiking in states where use is legalized. Meanwhile, efforts to draft consistent and effective laws limiting the use of marijuana by drivers are proving difficult.

Related: Report: Drugged-Driving Frequency Reaches New High

AAA reports that fatal crashes involving drivers who recently used marijuana doubled in Washington after the state legalized the drug. Complicating matters: Researchers are finding that existing legal THC limits in some states are arbitrary and unscientific, and could lead to unsafe drivers going free and others to be wrongfully convicted.

The study showed that the state of Washington’s percentage of drivers who had used marijuana before being involved in fatal crashes more than doubled to 17 percent between 2013 and 2014 1 in 6 drivers. AAA said Washington is an important case study in terms of what to expect in other states as legalization of marijuana spreads beyond fully legalized states like Alaska, Colorado, Oregon and Washington, as well as Washington, D.C. Peter Kissinger, president and CEO of the AAA Foundation for Traffic Safety, called the increase in crashes involving drivers with THC in their systems “alarming.”

Still, like many concerns surrounding the legalization issue, marijuana’s direct implication in fatal crashes remains hazy. Major federally funded clinical studies of the drug’s effect on driving have been conducted in recent years, and analysis of their results continues. A 20-month study in Virginia Beach, Va., showed that marijuana indeed impairs the motor skills and thought processes necessary for the safe operation of a vehicle. However, researchers acknowledged that after eliminating other factors at play in fatal crashes, marijuana’s actual contribution to the incidents was minimal at most, from an empirical standpoint.

Despite inconclusive evidence, some states have moved forward with the establishment of legal limits on THC for drivers similar to the 0.08 blood alcohol content limit. For example, Montana, Nevada, Ohio, Pennsylvania and Washington set legal limits at between 1 and 5 nanograms per milliliter of THC; a dozen others forbid the presence of marijuana in drivers’ blood outright.

The big problem with such limits, researchers concluded, is that they bear little relationship to objective reality, as the effects of THC from one person to another are wildly inconsistent.

“In the case of marijuana, this approach is flawed and not supported by scientific research,” Marshall Doney, AAA president and CEO, said in a statement about the state limits on THC in drivers’ bloodstreams. “It’s simply not possible today to determine whether a driver is impaired based solely on the amount of the drug in their body.”

In addition to there being no evidence that drivers become reliably impaired at specific THC levels, people who use the drug regularly may not exhibit impairment comparable to that of an occasional user. Moreover, in terms of enforcement, in the amount of time it would take to transport a drugged-driving suspect to a testing facility, THC levels could drop below legal thresholds.

AAA instead recommends that states use a two-tier system for enforcement that includes administering a positive test for marijuana use, and requires behavioral and physiological evidence of drug-related impairment, for which law enforcement officers would receive specialized training.

In the meantime, it’s incumbent upon the nation’s drivers to use their best judgment to determine whether they are safe to drive, regardless of the legal status of marijuana.

“Just because a drug is legal does not mean it is safe to use while operating a motor vehicle,” AAA said in a statement. “Drivers who get behind the wheel while impaired put themselves and others on the road at risk.”

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Former Assistant Managing Editor-News Matt Schmitz is a veteran Chicago journalist indulging his curiosity for all things auto while helping to inform car shoppers. Email Matt Schmitz

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