Testing for Marijuana-Impaired Driving Is About to Get a Whole Lot Easier


This is just a tidbit, but it’s an interesting one. Here’s the background: Legalized marijuana, which is pretty obviously gaining ground steadily, leads to higher marijuana use (duh) and thus to higher rates of driving while stoned. Or does it? The problem is that THC remains in your system for a week or more after you’ve smoked a joint, so even if you test positive at a roadside stop it doesn’t necessarily mean that you’re stoned now—or even that you’ve smoked within the past day, let alone the past few hours. As a result, drivers who are perfectly safe run the risk of being unfairly convicted of impaired driving, while drivers who are stoned can often escape conviction if they have a good lawyer.

Today, Keith Humphreys passes along the news that this might be about to change. It’s from a study in the Journal of Analytic Toxicology:

The JAT paper evaluated a different approach which may resolve these problems: Oral fluid sampling. The driver suspected of impairment is mouth swabbed at roadside and the saliva is placed in a machine, which rapidly prints out a result. This technology is fairer than urinalysis because it is only sensitive to recent marijuana use rather than use that happened a day ago or a week ago.

Of the devices the researchers tested in the study, the Dräger Drug Test 5000 had the best results. Assuming it doesn’t cost a mint, this technology could be a breakthrough for law enforcement as well as an important civil rights protection for people suspected of drug-impaired driving.

Like I said, just a tidbit. But an interesting one, especially given the obvious trajectory of marijuana legalization in America. If this technology pans out, it makes studies of marijuana-impaired driving more feasible and it removes one more argument from the arsenal of anti-legalizers.