Rush to judgment about slow driving

By Adrian Devitt-Lee On November 15, 2019
A cannabis leaf sits on the middle console of a car with a car key laid on top. There's a sun spot in the upper left hand corner of the photograph.

Slower drivers “likely pose a risk to roadway safety,” according to a recent study out of the University of Toronto. The goal of this research was to demonstrate the risks of driving while under the influence of cannabis. But the data only showed that cannabis users drive slower, which is one of the most consistent behaviors of high driving.

Unable to change their data and unwilling to accept that their THC-phobic assumptions might be misplaced, the researchers opted for this rather strange conclusion – that slower and less aggressive driving is one the dangers of lighting up.

“More research on the acute and residual effects of cannabis is needed,” they insisted. It sounds as if they’re waiting for a false positive result to affirm their fears.

What happens when cannabis consumers drive if they are not under the influence? Are they more apt to put the pedal to the metal?

No so, according to a recent report in Traffic Injury Prevention, which examined the lasting impact of cannabis use on driving a motor vehicle. Researchers at the University of Iowa, Yale, and Colorado State University collaborated on a study that tested a sample of thirty young drivers, about half of whom used cannabis a few times a week. Those using cannabis “drove slower than nonusers,” had “fewer and less variable steering reversals,” and “a lower accelerator pedal reverse rate,” the study concluded.

In other words, stoners, when sober, drive more cautiously and more consistently.

Sounds like good news, right? Apparently not, according to researchers at the National Advanced Driving Simulator. In their analysis they claim that “sober cannabis-using drivers may be at a greater risk for motor vehicle crashes, injuries, and deaths.”

But they neglected to mention, in their discussion, that nonusers were speeding on average, while cannabis enthusiasts tended to drive below the speed limit. It’s frightening to think what the editors at Traffic Injury Prevention consider safe driving if, to them, abiding by traffic laws is a “public health concern.”

Short description: 
Adrian Devitt-Lee, Project CBD's chief science writer, is employed as a research chemist by the University College of London.