U.S.: AAA Says There's No Scientific Basis For Laws Against Driving On Marijuana

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By Steve Elliott
Hemp News

Six states that allow marijuana use in one form or another have legal tests which supposedly serve to determine who is driving while impaired -- but those tests have no scientific basis at all, according to a study done by the largest auto club in the United States. AAA, as a result, has called for scrapping those laws.

The study was commissioned by AAA's safety foundation, and it discovered that it's not possible to determine impairment by setting a blood-test threshold for the level of THC, the main component of marijuana responsible the high. Yet the laws in five of those six states automatically presume a driver is guilty of driving while impaired if he or she tests higher than the limit, not not guilty if the level is lower, reports the Associated Press.

The AAA foundation recommends replacing those faulty laws with ones that actually rely on science, using specially trained police officers to determine if a driver is impaired on pot, backed up by a test for the presence of THC rather than a specific level. The officers would be responsible for screening for dozens of supposed indicators of marijuana use.

The foundation's recommendation to abandon the laws around marijuana and driving in Colorado, Montana, Nevada, Ohio, Pennsylvania and Washington comes as legislatures in several more states consider adopting similar laws.

At least three states, and as many as 11, will vote in November on ballot measures to legalize cannabis for either medicinal or recreational use, or both. Several legislatures are also looking at legalization bills of various kinds.

“There is understandably a strong desire by both lawmakers and the public to create legal limits for marijuana impairment in the same manner we do alcohol,” said Marshall Doney, AAA’s president and CEO. “In the case of marijuana, this approach is flawed and not supported by scientific research.”

Determining whether someone is actually impaired by marijuana, as opposed to merely having used it at some time in the recent past, is a lot harder than the simple tests developed for alcohol impairment.

First of all, there's no science whatsoever showing drivers become impaired at a specific THC level in the blood. It's a very individualized phenomenon, in other words. Drivers with high levels of THC in their systems might not be impaired at all -- especially if they partake on a regular basis, such as medical marijuana patients, for instance -- while novices with lower amounts of THC might be unsafe behind the wheel.

Frequent and heavy cannabis users can show persistent levels of THC long after use. Nine states -- including some that have legalized medical marijuana -- have "zero-tolerance" laws for driving that make not only the presence of THC in the driver's blood illegal, but also the presence of its metabolites -- which can linger for weeks after use.

That makes no sense at all, according to Mark A.R. Kleiman, New York University professor specializing in issues involving drugs and criminal policy. "A law against driving with THC in your bloodstream is not a law you can know you are obeying except by never smoking marijuana or never driving," Kleiman said.

Kleiman thinks that instead of switching to a new kind of law as AAA recommends, states should instead just make it a traffic violation.

While some studies show using marijuana while driving roughly doubles the risk of a crash -- and remember, those numbers include the novices who might actually be impaired -- talking on a hands-free cellphone quadruples crash risk, according to Kleiman. A blood alcohol content of .12, about the median in drunken driving cases, increases rash risk by 15 times, according to Kleiman.

Driving with "a noisy child in the back of the car" is equally as dangerous as using marijuana while driving, statistics show, Kleiman said.