High Road

CDOT received $750,000 from the state to develop a device to detect marijuana impairment in drivers


People drive high in Colorado all the time. You might know that from your own experience, having seen other drivers burning joints or people hopping into their cars after a sesh. Anecdotally, everyone knows it happens. But it’s also backed up by research. 

One recent survey of Native Roots customers (Boulder Weekly, “Street legal”, April 20, 2023) found that a total of 41% of people may drive under the influence of cannabis. That broke down into 22% who said it would depend on how much they consumed, 11% who said they were “very likely” to drive high regardless of the amount consumed, and 8% who will “probably” drive no matter what. 

Those numbers also reflect data collected by the Centers for Disease Control (CDC) in 2021. And according to the CDC, after alcohol, cannabis is the drug most often abused while driving. 

The department also notes, on its Marijuana and Driving webpage, “It is difficult to connect the presence of marijuana or concentration of tetrahydrocannabinol (THC) … to impairment in driving performance for an individual person.”

However, that might not be the case for long. Last year the Colorado Legislature passed HB22-1321, the Study of Devices Assessing Motorist Impairment bill. It granted the Colorado Department of Transportation (CDOT) more than $750,000 to “investigate devices that are capable of assessing cognitive and physical impairment of motorists to detect the presence of drugs other than alcohol during roadside sobriety investigations.”

If a police officer pulls someone over and suspects them to be under the influence of alcohol, they can easily administer a breathalyzer test and see exactly how intoxicated they are. But no such device exists for cannabis impairment. Some companies have tried to develop them without much success (Boulder Weekly,Windows of impairment and detection,” Sept. 16, 2021).

That lack of technology is contributing to a lot of high driving in Colorado, according to Sam Cole, traffic safety manager for CDOT.

“One thing that we hear over and over again from a lot of people,” Cole says, “is they don’t think it is dangerous [to drive high], and they don’t believe that law enforcement is equipped to tell if they’re actually high if they’re pulled over.”

Cole says police officers are highly trained to detect if a driver is high or not. But if they suspect inebriation and the driver blows a zero into the breathalyzer, the officer will likely take that person into the station and blood test them for cannabis. 

But even blood tests aren’t a fair indicator as to whether someone is currently under the influence of cannabis. THC stays in the bloodstream for between three hours and two days, depending on how frequent a person’s use is, while the effects of cannabis only last for between two and 10 hours. You could conceivably test positive for THC in your blood and be stone-cold sober at the time. 

Which was why the state passed HB22-1321, commissioning CDOT to study and develop a new device that could effectively assess whether a motorist was high. The bill was signed into law on June 6, 2022, and the funds allocated to CDOT came from the Marijuana Tax Cash Fund.

Aaccording to Cole, the device they’ve developed doesn’t measure THC. 

“It’s not going to be for saliva or blood or breath,” Cole says. “It’s going to be some sort of a device that measures your cognitive ability. Because that is the thing that is most affected by cannabis.”

To test and study this device, CDOT parked a van in several locations around the Front Range. In late April they were on the Hill in Boulder asking for volunteers to take the test and provide field data for their research. The legislation stipulates that CDOT must conduct and complete a study and report its findings no later than June 1, 2023. 

By next summer, Colorado police officers may be armed with a new cognitive test that can accurately assess whether or not someone is cognitively sharp enough to drive safely. 


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