This study shows why we will never — ever — develop an accurate marijuana breathalyzer.

Allow me to explain why. https://www.colorado.edu/today/2020/06/10/marijuana-concentrates-sharply-spike-thc-levels-dont-necessarily-get-users-higher

There are only two possible ways to measure cannabis impairment: a biological test (e.g. hair/blood/saliva) for some cannabanoid or other chemical in the body that serves as a reliable corollary for subjective impairment, the same way BAC does for alcohol; or...

...A direct test of subjective impairment, e.g. a tablet app that presents you with tasks designed to measure your memory/attention/awareness.

Both methods have insurmountable, fatal flaws.

The study described in the linked article proves why the biological route is out, *even if you can solve the time delay issue* (most current tests can only detect use in recent days or weeks, not whether someone is high at the moment of the test).

The reason? There simply is NOT a linear or otherwise predictable relationship between impairment and levels of THC or any other compound. In this study, people who smoked objectively stronger weed didn’t get subjectively “higher” than those who smoked lower-potency forms!

Different strains/forms make different people feel REALLY different and we have no idea why (spare me your unsubstantiated marketing babble about the “entourage effect”). But we DO know it’s not as simple as the amount of THC, which is a variable but isn’t reliably determinative.

(Btw, every actual cannabis consumer already knew this and could have saved scientists and policymakers the trouble, but the conversation about why those in power systematically undervalue people’s lived experiences is one for another time.)

“Okay, okay,” the breathalyzer entrepreneurs/electeds/scientists said, reluctantly acknowledging this annoying truth, “what if we test impairment itself? Apps are hip these days!”

No. When you test like this, you are taking a measurement “downstream” from THE ENTIRE BRAIN.

If people perform poorly on an app test, how would you know it was because of marijuana impairment? What if they have ADHD, or a learning disability, or they’re just tired, or they’re on prescription medication, or they’re old and unfamiliar w iPads, or literally *anything else*?

You will never convince me that an app, no matter how clever, can reliably tease out marijuana impairment from anything else that might be happening in the black box of the mind...

...especially without a baseline test of the same individual and extra-especially when we’d be using the result to decide whether to convict or incarcerate someone.

Marijuana breathalyzers are a naive fantasy that policymakers cling to as a way to signal that they’re fighting to keep us safe from those dreaded stoned drivers, encouraged by would-be contractors who want to get rich selling pothead detectors to police departments.

I’m not saying we should throw up our hands and let people chainsmoke Js behind the wheel. Drug-impaired driving IS bad! But we should really stop wasting taxpayer money on cannabis breathalyzer studies/committees/pilot programs. These gadgets are, and will always be, pure bunk.

(btw this study is from June — I’m belatedly catching up after seeing a more recent article about it. Still think it’s relevant, but noting the date and the fact that it’s not breaking news in the spirit of full disclosure.)

Also: I’ve raised these issues before (in stories, my newsletter, and in radio appearances) and every time, without fail, one of these gadgeteers emails me to explain how dumb and wrong I am, yet their products *never* pan out or make it to market...