Driving While High: What's the Real Story Here?
State lawmakers have set the legal limit of 5 nanograms of THC in the blood system.
Published on February 1, 2016

They're heeere! Pot breathalyzers are coming to a town near you. As pot becomes mainstream, law enforcement will inevitably react with measures to prevent drugged driving. Several states are already addressing the issue and they're in cahoots with local law enforcement. Find yourself a designated driver, because police will be on the beat.

The Colorado State Patrol (CSP) recently announced its intention to roll out a statewide marijuana testing program aimed at nabbing drugged drivers. In preparation, the CSP has trained an army of 125 troopers to enforce the state's 5-nanogram limit. Colorado introduced the 5-nanogram limit in 2013. Per the new program, the police are experimenting with five pot breathalyzer prototypes. At least one breathalyzer tests saliva samples. Oakland-based Hound Labs, for instance, is developing a pot breathalyzer that can detect cannabis metabolites in a single breath.

Cannabis may impair psychomotor skills, but not nearly at the rate alcohol does. Recently, the National Institute on Drug Abuse, the Office on National Drug Control Policy, and the National Highway Traffic Safety Administration funded a study exploring the impact of cannabis on driving. Researchers explained that alcohol "significantly increased lane departures/minimum and maximum lateral acceleration; these measures were not sensitive to cannabis." In addition, cannabis-consuming drivers "may attempt to drive more cautiously to compensate for impairing effects, whereas alcohol-influenced drivers often underestimate their impairment and take more risk."

In the study, cannabis users only reached the equivalent to the point of alcohol intoxication (0.08 breath alcohol) when they had concentrations of 13.1 µg/L THC in their system. In other words, alcohol impairs you at more than twice the rate.

Drivers in the study consumed cannabis then drove for 45 minutes in a driving simulator based on a 1996 Malibu sedan. Researchers weighed in on an array of several defining factors.

Another study took a look at seven different driving studies and 7,934 drivers. The study reported “Crash culpability studies have failed to demonstrate that drivers with cannabinoids in the blood are significantly more likely than drug-free drivers to be culpable in road crashes.”

The Canadian Senate reported that cannabis use has little or no effect on driving. “Cannabis leads to a more cautious style of driving, [but] it has a negative impact on decision time and trajectory. [However,] this in itself does not mean that drivers under the influence of cannabis represent a traffic safety risk, the Senate said. “…Cannabis alone, particularly in low doses, has little effect on the skills involved in automobile driving.”

Using a breathalyzer might not be an accurate way to measure cannabis at all. “What 5 ng/mL means in terms of actual impairment is hard to calculate, as THC levels in the blood peak quickly following inhalation then decrease rapidly according to complex pharmacokinetics, making it almost impossible to extrapolate backwards from the concentration of THC at the time of the blood test to the concentration at the time of the traffic accident.” wrote researchers.

In the event that you are pulled over, the ACLU has issued some core guidelines. Know your rights and ask the cop important questions like “Am I free to go?”, “I wish to remain silent.”, and “I do not consent to a search.” You're never required to provide a complete explanation.

Benjamin M. Adams
Benjamin Adams is a freelance writer whose work has appeared in a slew of publications including CULTURE, Cannabis Now Magazine, and Vice. Follow Ben on Twitter @BenBot11
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