Los Angeles is bringing a new tool to the streets in its fight against stoned driving.
According to ABC News, the LA city attorney’s office is used a so-called marijuana breathalyzer to test motorists for the presence of cannabis metabolites in their systems. The results could be used to convict drivers on DUI charges.
The term “Breathalyzer” isn’t quite accurate, though. Those are small hand-held devices, and motorists blow into them to measure alcohol concentration on the breath. They’re used at police stations and, often, at roadside traffic stops to gather evidence against suspected drunk drivers.
Drugged driving is illegal everywhere in the United States. But different jurisdictions use different approaches to target people who get behind the wheel high. In most states, prosecutors must prove a motorist’s driving was actually impaired, using a totality of the evidence.
In others, it’s enough to prove a driver had a certain amount of active marijuana metabolite in her blood. This is known as the “per se” approach. The threshold amount of pot varies from state to state, in large part because researchers have yet to establish any clear correlation between THC levels and impaired driving. Regular users, for example, may not be impaired even with substantial amounts of the metabolite in their systems.
Still other states, including Arizona, impose DUI penalties on anyone found driving with any amount of THC metabolites in the blood. This is known as “zero tolerance per se” law.
California follows the first approach, applying the totality of the evidence. This might include a motorist’s actual driving behavior (crossing the line, speeding), test results, behavior when interviewed during a traffic stop and performance on a field sobriety test. Oral swab results may be part of the overall evidence.
But the tests don’t measure how much marijuana remains in the system – only that some does. That makes it less useful, and less threatening to drivers, in states where per se laws are graded, but especially powerful in states with zero tolerance laws. In California it’s just a piece of the overall picture.
Stoned driving is dangerous and ill-advised under any circumstances, but it’s nowhere near as dangerous as drunk driving. Studies show pot raises a driver’s risk of crashing by a factor of 1.43, while drinking and driving increases the risk by a factor of 13.64.
Overly rigid driving laws pose a real risk to marijuana users, especially medical users who smoke heavily. Marijuana doesn’t work on the bloodstream like alcohol does, and a simple measurement of metabolites can’t give you a reliable reading on an individual user’s sobriety.