Marijuana driving laws

Cannabis Station, Denver, Colorado

New studies commissioned by the AAA Foundation for Traffic Safety seem to contradict each other on the risks of driving under the influence of marijuana.

Colorado’s marijuana laws, and those in several other states, are referred to in the study.

According to AAA, after Washington State legalized recreational use of marijuana, fatal crashes involving drivers who had recently used pot doubled. “[T]hese findings serve as an eye-opening case study for what other states may experience with road safety after legalizing the drug.” However, the studies also found that the legal limits (also called per se limits) for marijuana and driving are “arbitrary and unsupported by science.”

Laws Not Based on Science

In fact, the new studies find that six states that allow marijuana are using legal tests that are not based on science, writes the Associated Press in an article appearing in The Gazette. AAA has recommended that the six states — Colorado, Montana, Nevada, Ohio, Pennsylvania, and Washington — scrap its per se laws, even as other states are considering adopting such laws.

The legal marijuana blood limits are not an accurate way to measure whether a driver is impaired, writes Mary Wisniewski for the Chicago Tribune, and let unsafe drivers go free, while others are wrongfully convicted. That is because some people can be impaired with low levels of THC (the psychoactive component of marijuana), while others can drive safely with higher levels in their blood.

This is because the body does not metabolize marijuana the way it does alcohol, Wisniewski writes:

So while a person with a blood-alcohol level of .08 or higher is considered too drunk to drive, it’s not possible to say the same thing absent other evidence about a person testing at 5 nanograms per milliliter of blood of THC — the level used to find impairment by Colorado, Montana and Washington, the study found.

Behavioral and Physiological Evidence

AAA is suggesting that states use other types of evidence to determine whether a driver is impaired from marijuana, including behavioral and physiological evidence. These could include field sobriety tests, seeing if a driver has bloodshot eyes, and if he or she can stand on one leg, for example. J.T. Griffin, chief government affairs officer for Mothers Against Drunk Driving, said such evidence has stood up in court.

Colorado law enforcement officers are trained to detect drivers’ impairment from drugs, many of them having taken a course in Advanced Roadside Impaired Driving Enforcement, the Colorado Department of Transportation (CDOT) writes on its Marijuana and Driving page.

If a driver refuses to take a blood test, he or she is considered to be a high risk driver, and his or her driving privileges will be revoked. That driver will then be subject to level 2 alcohol education and therapy classes, and a mandatory ignition interlock for two years, as specified by law.

Drivers Had Other Drugs in Blood

Regarding the study finding that Washington State’s marijuana driving deaths had doubled, Wisniewski writes that according to that study, most of the drivers with THC in their blood also had alcohol or other drugs in their systems when they crashed. Those drivers with THC in their systems were “not necessarily” impaired or at fault in those accidents.

In a comment to The Gazette article, Jake Topper writes: “No one should be driving when high.” He adds that he admires AAA for attempting to find a scientifically proven and reliable way to measure marijuana impairment.

Image by Jeffrey Beall, used under its Creative Commons license.

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