Is a Marijuana Breathalyzer in the Offing?

Posted by Jon Ibanez on September 14th, 2015

Many are saying that California will be the next state in the Union to legalize recreational marijuana. If their predictions are correct, that would make California the sixth state to do so. Currently, Washington, Colorado, Alaska, Oregon, and Washington D.C. have all legalized recreational marijuana. Although California has not yet legalized recreational marijuana, it has decriminalized marijuana and allows the use of medical marijuana for medical purposes.

With California and other states on the cusp of legalization of recreational marijuana, law enforcement agencies are clamoring for technology that will help them determine how stoned someone is for purposes of driving under the influence.

In June of this year, Cannabix Technologies Inc., a company based out of Vancouver, issued an update on what it hopes to be the first widely used marijuana breathalyzer. According to Cannabix’s website, a prototype has been developed and is currently undergoing testing. According to the company’s founder, retired Canadian police officer Kal Malhi, the device will be able to detect the use of marijuana within two hours.

Lifeloc, a Colorado-based company which already makes and distributes alcohol breathalyzers is also in the race to develop a marijuana breathalyzer.

"I think the first breathalyzer on the market will be a simple ‘yes’ or ‘no’ for the presence of THC at the time of the test, and in that sense it won’t provide a quantitative evidential measure," Barry Knott, the chief executive of Lifeloc, told Reuters.

If developed, the new marijuana breathalyzer would replace the rather inefficient blood test to determine how much THC (tetrahydrocannabinol), the active component of marijuana, is in a person’s system.

Many states that have legalized marijuana either recreationally or medically have set a "per se" limit, or bright line rule on how much THC can be in a person’s system while driving ranging from 0 to 5 nanograms per milliliter of blood.

It is well known that the "per se" limit for how much alcohol can be in a person’s system is 0.08 percent blood alcohol content. With alcohol, there is a fairly strong correlation between blood alcohol content and intoxication. In other words, there is a high probability that a person with a 0.08 blood alcohol content is feeling the effects of alcohol intoxication such that they cannot operate a vehicle as a reasonable and sober person would.

So can the same be said for nanograms of THC per milliliter of blood? Unfortunately, no.

Notwithstanding "per se" THC limits in many states, the correlation between nanograms of THC per milliliter of blood and marijuana intoxication is extremely weak.

Unlike alcohol, THC is fat soluble which means that it leaves the body at a much slower rate. In fact, chronic users of marijuana can have THC in their blood weeks after use. Alcohol, on the other hand, is water soluble and dissipates at a rate of about 0.015 percent per hour. This means that, depending on how much alcohol someone drank, a person can sober up within hours.

This means that someone who has smoked marijuana three weeks ago can still be arrested in states with a "per se" THC limit even though they are no longer under the influence of marijuana and perfectly sober.

It is unclear whether the marijuana breathalyzers currently being developed will quantify how much THC is in a person’s system. Not that it matters. The amount of THC in a person’s system has nothing to do with how intoxicated they are and, consequently, how much of a danger they are to the roads.

Until a marijuana breathalyzer can determine how intoxicated someone is, we run the risk of arresting sober people for DUI. 

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