Recreational marijuana use is now legal (or about to be) in 11 states and Canada. Driving under its influence is not. But if police suspect someone is driving high, they’ll have a difficult time proving it: Marijuana tests typically rely on urine samples, take days to analyze, and may only indicate that someone has used marijuana over the past days or even weeks, not whether they are actively impaired.
In response, several startups say they are building “pot breathalyzers” that will instead (eventually, they swear) deliver results about recent marijuana use, on the spot. The most obvious use for these devices is patrolling roads. But there’s another place where it could be very important to tell the difference between legal marijuana use last weekend and current impairment: your job.
While stoners like to debate whether driving high is actually dangerous (for the record: multiple meta-analyses of multiple studies say yes; one study conducted by the National Highway Traffic Safety Administration says not really), there’s no doubt that marijuana use is getting people fired.
The U.S. Department of Transportation requires drug testing for “safety-sensitive” positions like pilots, bus and truck drivers, and railroad operators. Federal government contractors and those receiving federal government grants are required to maintain a “drug free” work environment. And manufacturing facilities, warehouses, and wholesalers may also drug test for safety reasons. After a workplace accident, employers may use a positive drug test to argue that injuries or damage were caused by a worker’s impairment, rather than the company’s negligence.
Marijuana is the most commonly flagged substance in workplace drug tests, according to Quest Diagnostics, which sells testing services to employers. Nearly 3% of all screenings the company processed in 2018 tested positively for the drug (4.4% of screenings tested positive for any substance).
As marijuana becomes legal in more states, however, the usefulness of a test that determines whether…