California Wants to Extinguish Stoned Driving

By Dirk Hanson 07/12/11

How much marijuana impairs a driver? Nobody knows.

Busted for bloodshot eyes?
Photo via thinkstockphotos

Law enforcement says it needs a new enforcement tool, the Drug Czar blames the problem on marijuana, the ACLU says “zero tolerance” is a terrible idea, and nobody seems to remember the fate of Colorado’s recent attempt to legislate “drugged driving.” Undeterred, California is pushing ahead in the wake of reports that one out of four drivers in fatal accidents tested positive for drugs, as we reported. The California Highway Patrol says that “fatalities in crashes where drugs were the primary cause and alcohol was not involved jumped 55% over the 10 years ending in 2009,” according to the Los Angeles Times. And Drug Czar Gil Kerlikowske said, as Drug Czars always do, that “marijuana is a significant and important contributing factor in a growing number of fatal accidents.” That assertions remains controversial, but so far 13 states have adopted zero-tolerance laws, while 35 states, including California, have no formal statutes, but rely instead on “the judgment of police to determine impairment,” as the Los Angeles Times phrased it. And that is exactly the problem. Medical marijuana advocates are convinced that the idea is to make it impossible for pot users to drive a car for days, or perhaps even weeks, after using their medicine. Meanwhile, federal scientists are salivating over the prospect of a spit test that would enable a cop to swab your mouth and get drug results immediately. But that remains a law enforcement wet dream rather than a reality. In the meantime, California police use a complicated 12-point examination system involving standing on one leg, and estimating the passage of 30 seconds, and a blood pressure check, and a look into the driver’s pupils, and several other hoops to jump through, all of which is supposed to enable an experienced cop to tell whether you are too high to drive. Not nearly good enough, says the American Civil Liberties Union (ACLU), which advocates the “Pennsylvania Model” of a cut-off level for marijuana of 5 nanograms per milliliter of blood. The ACLU says this is consistent with research by NORML on the impact of cannabis on driving skills.

 “Everybody wants a magic number, because that makes it easy,” according to a toxicologist who serves as an expert witness in drug trials. Juries seem to agree that the current system needs a rebuild. For example, a medical marijuana user in San Diego was recently acquitted of manslaughter stemming from a fatal car crash he was involved in after smoking marijuana. While blood tests showed a high level of marijuana metabolites in his blood, the jury heard so much conflicting toxological testimony on what constituted impairment that they threw up their hands and set him free. Measuring delta-9 THC, and determining at what level it impairs driving, is a scientific endeavor still in its infancy.

Please read our comment policy. - The Fix
dirk hanson.jpg

Dirk Hanson, MA, is a freelance science writer and the author of The Chemical Carousel: What Science Tells Us About Beating Addiction. He is also the author of The New Alchemists: Silicon Valley and the Microelectronics Revolution. He has worked as a business and science reporter for numerous magazines and trade publications including Wired, Scientific American, The Dana Foundation and more. He currently edits the Addiction Inbox blog. Email: [email protected]