Marijuana Breath Detector

Posted by Jon Ibanez on August 29th, 2019

According to the California Highway Patrol, the number of arrests for driving under the influence of marijuana has increased since recreational marijuana in California became legal in 2018. Yet, determining when someone is under the influence of marijuana to a degree that makes them incapable of safely operating a motor vehicle remains as difficult as it always has been…or has it?

California Vehicle Code section 23152(f) makes it “unlawful for a person who is under the influence of any drug to drive a vehicle.”

Quite clearly, marijuana is a drug even if it is recreational. Whether a transportation device qualifies as a “vehicle” for purposes of this law is a different subject for a different day. The bigger question, however, is whether someone is “under the influence” after having smoke marijuana.

To be “under the influence” as the result of consuming marijuana, a person must have his or her mental or physical abilities so impaired that he or she is unable to drive a vehicle with the same caution of a sober person, using ordinary care, under similar circumstances.

While this definition might sound nice, it is still difficult to determine how much marijuana an individual must consume before they are so “high” that they are unable to drive a vehicle with the same caution of a sober person, using ordinary care, under similar circumstances.

Unlike alcohol, there is little correlation between the amount of marijuana someone has consumed and how impaired a person is.

Alcohol is water soluble, which means that it enters and leaves the bloodstream fairly quickly. Additionally, a person’s blood alcohol content, which can be determined rather quickly and accurately, has scientifically been shown to correlate with how drunk (i.e. impaired) someone is. Every state, with the exception of Utah, has a blood alcohol content limit of 0.08 percent because, generally speaking, that is the point at which alcohol begins to affect a person’s motor skills, thus making them “under the influence” for purposes of a DUI with alcohol.

THC (tetrahydrocannabinol), the psychoactive component to marijuana, on the other hand, is fat soluble. Therefore, unlike alcohol, it can stay in a person’s system for much longer than alcohol. In fact, regular users of marijuana can still have THC in their systems weeks after having consumed marijuana and certainly long after being high, which necessarily means that it cannot and should not be used to determine how high someone is, and whether they are “under the influence.” Yet, current blood tests only detect the amount of THC in a person’s system, but there is no way to determine how “high” someone is.

Oakland based Hound Labs is trying to change this by creating the first breathalyzer to measure “recent” marijuana and alcohol use on the breath.

“When you can you find THC in breath, and that can require some incredibly sensitive tools, but when you can find it, then you know that the person used very, very recently,” said Dr. Mike Lynn, emergency room physician, reserve deputy sheriff, and founder of Hound Labs.

Working in conjunction with UCSF, Hound Labs determined that THC can be found on a person’s breath.

“We found THC in all twenty test subjects, and what was really interesting, is that the THC peaked at about 15 minutes, and then it went out of the breath within 2 to 3 hours,” said Dr. Lynn.

According to Dr. Lynn and Hound Labs, if THC is found on the breath, it means that a person had smoked within the last few hours. They also determined that the first two to three hours following marijuana consumption is when a driver is at the greatest risk for being impaired.

Hound Labs were granted $30 million in funding to continue to develop and manufacture the marijuana breath test to be used by law enforcement by the end of the year.

While it may be a step in the right direction in finding the elusive answer to the question, “When is someone too high to drive?” issues remain. When Hound Lab’s device detects that someone consumed marijuana “recently,” how recent is it? Does “recent use” account for even negligible amounts of marijuana consumption? Will “recent use” change the way we draft our DUI of marijuana laws?

Bottom line is that, before we get too carried away, we need to make sure that whatever safeguard and/or preventative measures we put in place to stop high drivers do not infringe on the rights of people who consume marijuana safely and lawfully.

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