Thread by @WIRED

Every state prohibits driving under the influence of weed, but no state has found a reliable way to sort the stoned from the sober—defaulting primarily to another flawed method of assessment: human judgement. wired.trib.al/1HFLPdc 1/9

Some states have implemented a 5-nanogram-per-milliliter threshold, but cannabis pharmacokinetics are so variable that even if two people share a joint, one person might dip below that level within two hours and the other might stay above it for the rest of the week. 2/9

Stoned driving is therefore one of the biggest unresolved sticking points in the long slide toward legalizing marijuana in the US—a Kafkaesque quandary with no clear solution. 3/9

About 15 years ago, Charles Duffy, then a neurobiology researcher at the University of Rochester Medical Center, set out to build a device that could quickly and effectively assess cognitive impairment. 4/9

Duffy’sdevice administered a 10-minute test that would evaluate memory, visual acuity, processing speed, reaction time, and higher-order reasoning and concentration skills known as “executive function.” He called his device Cognivue, and it was cleared for use in 2015. 5/9

An internist who once led a Doctors Against Distracted Driving campaign began using the Cognivue device with his elderly patients in Rochester, New York in 2019. He mentioned it to his law enforcement and political contacts as a potential tool for evaluating impaired drivers. 6/9

If Cognivue could show that scores on their computerized test demonstrated impairment better than the highly trained cops or THC in the blood, New York just might implement the first objective measure for stoned driving in the United States. 7/9

FInd out more about how Cognivue is cracking down on impaired drivers. Read the full article here: wired.trib.al/1HFLPdc 8/9

Get your first year of WIRED for less than $1 a month and get unlimited access to our longform features, buying guides, and tech news. wired.trib.al/y56Mi3d 9/9