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Cops Will Soon Test for Marijuana Intoxication at Traffic Stops. This is How They’ll Do it

Here is what cannabis-assisted drivers can expect when they see the flashing lights of a traffic stop.

drug test traffic stops

(Photo by Andrew Stawicki/Toronto Star via Getty Images)

In recent years it’s become clear that legal weed doesn’t necessarily mean unhinged freedom.  A decade’s long cry for a legal market means government regulation, and the government is rarely on the side of fun. Still, on the off chance, a highly motivational strain of Sativa launches cannabis consumers out of the comfort of their homes and into their cars, law enforcement needs to determine whether those individuals are sober enough to drive. In any case, a cannabis-assisted car ride is probably a bad idea, but the question remains: what can we expect when we encounter at a traffic stop?

Urine and hair tests work but come with significant problems in establishing an accurate timeline. With urinalysis and hair analysis, police can determine whether you were buzzed in your living room a week ago. But the issue with those tests is not only that they require lab analysis, but also that they can’t determine the rate of intoxication at the time the driver was pulled over.

That’s where the slightly more sanitary yet equally gross spit-test comes in. Police in Canada have been testing their spit machines for a year now in preparation for the legal recreational market in 2018, and they claim the technology is ready to go.

But many critics insist that spit-machines are not only legally dubious, but they’re also inaccurate.

“If measured THC levels don’t correlate reliably with impairment, criminal defense lawyers will pulverize the testing in courts.” Writes Colby Costi of the National Post. “And there’s more bad news. The devices themselves are in their infancy, in the full sense of that word: undeveloped and clumsy.”

Even if a regulated THC level is agreed upon, critics say, issues of impairment will still arise as different people have different levels of tolerance.

How Long Until Cops Can Test For Weed At a Traffic Stop 167074704 Cops Will Soon Test for Marijuana Intoxication at Traffic Stops. This is How Theyll Do it
(Photo by: BSIP/UIG via Getty Images)

Among the companies researching such technology are Hound Labs and Cannabix Technologies who are developing the cannabis equivalent of the alcohol.

Hound Labs, in particular, has raised $8.1 million from the investment firm Benchmark to develop a handheld device. The company claims that their product will be available to law enforcement by the end of the year and that it detects THC particles in the breath up to two hours after use. Hound Labs have spent the last two years testing their device for commercial markets.

But how effective is their technology? A study conducted by the National Institute of Standards and Technology in Colorado and published in Forensic Chemistry suggests that detecting THC in breath is possible. While their technology was not included in the NIST study, The Hound® breathalyzer will have the dual capability of measuring both THC and alcohol in breath.

“Breath sampling is attractive because it is non-invasive, can be portable, and has been shown to indicate recent use within [thirty minutes to two hours].”  The Hound Labs technology was developed specifically to measure the amount of THC in breath in picograms. 

However, publications like the Scientific American are skeptical of those who say accurate and usable devices are just around the corner.

“Although many researchers and companies dream of fielding a roadside test for driving under the influence of cannabis, such a product may still remain years away from practical service use.” Writes David Downs, “Millions of dollars’ worth of speculative research will likely be needed to correlate data about consumption amounts with actual driver impairment.”

As for the effects of marijuana on drivers, studies have shown that cannabis can reduce reaction time in drivers and impair their ability to operate a vehicle. But a review of seven studies cited by the marijuana advocacy group NORML found that “Crash culpability studies have failed to demonstrate that drivers with cannabinoids in the blood are significantly more likely than drug-free drivers to be culpable in road crashes.”

Still, the main obstacle to any testing mechanism is the people who use medical marijuana, which often has very minimal psychoactive effects while also containing low amounts of THC. It has resulted in lawsuits in Canada on behalf of the trucking industry and companies which claim the current testing methods are not accurate enough to determine impairment.

So while law enforcement searches for the best way to identify buzzed drivers, a reliable method still seems a long way away. Until then, spitting at police officers may soon be a request rather than a criminal offense.

How Long Until Cops Can Test For Weed At a Traffic Stop  Cops Will Soon Test for Marijuana Intoxication at Traffic Stops. This is How Theyll Do it
(Photo by Nigel Duara/AP)

Correction: A previous version of this article referenced The Hound® breathalyzer in relation to a study by the National Institute of Standards and Technology. While the NIST study did analyze technology used to measure THC, it should be noted that the technology of Hound Labs was not analyzed and that the data sets may be different. This piece has since been updated.

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October 10, 2017 — Last Updated December 20, 2019
Written by Miroslav Tomoski

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