To date, no successful “marijuana breathalyzer” device has been introduced to the market.
How do you tell if someone is high or not—but, more to the point, how do you tell if they’re too high to drive? It’s a question that’s been dogging law enforcement throughout the marijuana legalization era.
One technique, sought after by law enforcement and promised by several teams of ambitious entrepreneurs and researchers, is a “marijuana breathalyzer,” a hand-held device that—like an alcohol breathalyzer—could deliver a quick and accurate quantification of impairment that would subsequently prove convincing in court.
How could you do that? An alcohol breathalyzer works because it can measure the amount of alcohol in the blood, some of which is exhaled through the lungs. But marijuana does not work like the same way as alcohol.
In fact, as a study from researchers in Australia published earlier this month found, both blood and “oral THC fluid are relatively poor or inconsistent indicators of cannabis-induced impairment,” the University of Sydney announced in a news release.
So in order for a marijuana breathalyzer to work, that breathalyzer would have to analyze an entirely different biomarker—which in suggests that anything akin to “breathalyzer” wouldn’t be able to indicate cannabis impairment in the same way as an alcohol device, at all.
“This contrasts with the much stronger relationship between blood alcohol concentrations and driving impairment,” according to the researchers, whose work was published in the journal Neuroscience & Biobehavioral Review—and whose findings have “implications for the application of drug-driving laws globally,” they said.
One way to digest this news is that marijuana breathalyzers simply don’t work, though that analysis is rejected by researchers and entrepreneurs still trying to prove otherwise.
While there has yet to be any clear sign of a “drugged-driving” epidemic, studies have shown an increase in incidences of traces of cannabis discovered in drivers’ bodies after accidents. But whether this means the driver was high or not is far from clear.
In this, police and public-safety minded lawmakers have been spoiled by alcohol breathalyzers. Breathalyzers give police a quick and accurate-enough reading of a driver’s blood-alcohol count, because biology. The human body starts to break down alcohol almost immediately, and impairment exists as long as alcohol is present. That maxim—if it’s present, it’s impairment—is how alcohol works in the body, and why alcohol breathalyzers work.
Notably, cannabis does not work like this—blood and urine tests can detect fat-soluble cannabis metabolites that have long since stopped having an effect—but that hasn’t stopped a bevy of ambitious entrepreneurs from promising workable, viable “marijuana breathalyzer” technology.
However, to date, no successful “marijuana breathalyzer” device has been introduced to the market. And if a breathalyzer sought to measure impairment based on blood or saliva levels, it would not be reliable enough to satisfy a judge or a jury in the fact of a committed defense attorney—which means, in turn, it’s not good enough for police.
To their credit, makers of marijuana breathalyzers have tried to measure cannabis impairment in other ways. One device, a long-promised gadget from Oakland, California-based Hound Labs, says it might be able to determine whether someone had smoked weed in the past few hours based on molecules in the breath—but that would only indicate use, not impairment. And it’s unclear how that would adjudicate whether someone wasn’t completely ripped on edibles.
Another device, introduced by researchers from the University of Pittsburgh, says it can measure cannabis levels in the breath using single-walled nanotubes and steel wool to capture “THC from exhaled marijuana smoke,” according to research published in 2019. However, given the Australian researchers’ findings, it’s unclear how a biomarker like “breath” would give any more reliable an indicator of impairment than THC in blood or saliva.
“I can understand how people like to quantify things,” as Dr. Peter Grinspoon, a physician at Massachusetts General Hospital and erstwhile lecturer at Harvard Medical School, told Discover Magazine. “However, it just doesn’t work like that.”
This is not to say law-enforcement has no way to tell if someone is high. Cops trained as drug-recognition experts can use metrics like response times, dilated pupils or red eyes, and basic facts like scent or the sign of smoke to make a case that someone is stoned, or has just smoked cannabis. Field sobriety tests are also effective.
And, as California NORML’s Dale Gieringer told Discover Magazine, a marijuana breathalyzer could be useful in jobs that prohibit cannabis use of any kind, such as airline pilots or bus drivers, to see if someone so much as consumed. How high they would be is another question that would probably be unanswered.
Which means that for now, the promise of marijuana breathalyzers is still unfulfilled. Unless there’s a scientific breakthrough to find a biometric that indicates intoxication that’s currently unknown, marijuana breathalyzers may never work.Drugged Driving Marijuana New Drug Trends