Cannabis & Driving Impairment

With nine states voting on marijuana reform this November, driving under the influence of cannabis is going to become a situation that requires standards and regulations to protect users and non-users alike. At this point in time, there is no approved and reliable test to determine whether a driver is impaired to the point of being a hazard on the road.

What rules have already been set?

The legal limit in Colorado and Washington is 5 nanograms of THC, an amount that other states are considering as well. However, a study done by researchers at the University of Iowa sponsored by the National Highway Traffic Safety Administration, National Institute of Drug Abuse and the Office of National Drug Control Policy showed that users could use up to 13.1 nanograms of THC before demonstrating the same level of impairment as having a .08 breath alcohol level — the legal limit. This was the first official study on the matter, and more data should hopefully lead states considering legalization to make better-informed laws in regard to limits and regulations.

In California, police officers rely heavily on field sobriety tests to determine if the driver is under the influence. There are three kinds of sobriety tests that they use: the Horizontal Gaze Nystagmus Test (77% accurate), the Walk and Turn Test (68% accurate) and the One Leg Stand Test (65% accurate). When the officer has any reason to believe that you failed any of the above tests, they can demand a blood, urine or breath sample. Blood and urine show THC for weeks after use, and there isn’t currently an approved breath test for THC. The officer can also request a saliva swab, however saliva can show THC for up to three days after use.

What’s on the horizon?

California based Hound Labs is currently in the process of patenting their cannabis breathalyzer system, which seems very promising and is the most advanced method yet. Their product tests for THC in picograms (parts per trillion) and measures the quantitative amount in the breath, not just a positive or negative. They also claim that their test measures for edibles consumed as well, which is really important. Edibles have a much more delayed effect on the user than smoking or vaporizing, and when processed in the liver, the THC turns into a THC metabolite, which has a much more psychoactive effect. Prototypes of the breathalyzer have been used in various counties in California to gather information with great success. The next step after approving the technology will be to determine fair and safe levels for drivers.

What can I do now?

With no current regulations nationwide, the best thing to do is to be cautious. Stay hydrated, don’t drive immediately after consuming, and most importantly — know your own body. Cannabis affects everyone differently, and if you aren’t sure how you might react to something new, give yourself a generous buffer time before getting behind the wheel.

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