Driving on cannabis

With the November election drawing near, the debate over legalizing recreational use of marijuana is heating up in several key states, including California. The Adult Use of Marijuana Act (AUMA) has officially made it onto the California ballot as Proposition 64 and both its supporters and opponents have had a lot to say. One common criticism of Prop 64 is that it does not address cannabis users driving under the influence of cannabis and, more specifically, that it does not include a meaningful test for determining when a driver is impaired. In Colorado  and Washington, blood tests are used by law enforcement to determine the level of active tetrahydrocannabinol (THC) in drivers’ blood, and drivers with 5 nanograms or more of THC per millimeter of blood can be legally prosecuted for driving under the influence (DUI).

However, a recent study from the American Automobile Association (AAA) found that setting a blood test limit for marijuana is not backed by scientific evidence since cannabis is metabolized differently than alcohol and there is no proof people are impaired at an exact blood THC level. With blood tests, some drivers can test positive for high THC levels days after they last consumed marijuana. Thus, Prop 64’s supporters question reports from Colorado and Washington that purport to show marijuana-related traffic fatalities have gone up since recreational legalization. Instead, Prop 64 allocates some of the tax revenues raised from recreational marijuana to develop training and technology to address drugged driving in California.

Currently, California drivers can be prosecuted for driving under the influence of marijuana if it impairs their ability to drive a vehicle with the caution of an ordinary, sober person. There is no set test for determining impairment, but law enforcement officers use several signs as evidence of impairment, including performance on a field sobriety test. With the passing of the Medical Cannabis Regulation and Safety Act (MCRSA) last year, the California legislature commissioned researchers at UC San Diego to develop new field sobriety tests specifically for marijuana. The goal of this research is to find a way to determine if a driver is impaired by testing various body fluids (blood, saliva, breath) and performance on roadside cognitive tests. Earlier this year, California lawmakers proposed the use of oral swab tests as further evidence of impairment.

But one Oakland-based startup company is trying to get ahead of the curve. In 2015, we wrote about the “drugged driving laws” emerging in legal marijuana states and stated at that time that marijuana breathalyzers were nothing more than an idea. Today Hound Labs claims to have turned that idea into a reality and has begun testing its devices right here in California. They claim their marijuana breathalyzers can detect recent cannabis consumption, including marijuana-infused foods. The intent of the test is to determine if a driver is driving while high as the company claims THC only stays in a person’s breath for a short amount of time, meaning they must have consumed the marijuana in the past couple of hours.

Initial field tests were conducted by local California law enforcement on voluntary drivers who were pulled over for driving erratically or committing a traffic infraction. (Note: no drivers were harmed or arrested in the testing of these devices, though any drivers that tested positive for recent marijuana use were required to find a safe ride home. Also, one driver was arrested for driving under the influence of alcohol.) The company plans to move forward with wide distribution of its breathalyzers early next year.

If marijuana breathalyzers prove to be an effective tool for measuring driver impairment, new laws will need to be written based on breath measurement rather than blood measurement of THC. Still, further tests are needed to develop a new standard for how THC breath levels are correlated to driving performance. For now, the drugged driving issue remains up in the air for not only California but for all other states that have or will soon have legal marijuana markets.