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.

Herb.com October 2017