Marijuana breath tests may be coming to California roadways

by | Aug 6, 2021 | Criminal defense |

It’s standard procedure any time a California state trooper, sheriff’s deputy or local police officer pulls someone over on suspicion of drinking and driving: the officer asks the driver to blow into a device that measures the level of alcohol in their system.

Police on patrol have had these roadside breath test devices in their arsenal for decades. But currently, police in Contra Costa County and the rest of California have no way of testing a driver for marijuana at the scene. That could change soon, though. As Discover Magazine reports, several companies are working on marijuana breath testers that they claim will be accurate and reliable.

Detecting ‘driving while high’ is a challenge

California was among the first states to legalize cannabis for medical use in 1996. Five years ago, the state fully legalized marijuana via Proposition 64. But just like with alcohol, driving under the influence of marijuana remains against the law. And without a device to measure the level of THC in a driver’s body, officers tend to rely on field sobriety tests — which are controversial due to their being so subjective. Two officers could come to different conclusions about a driver’s performance on those tests, based on factors like the officers’ judgment and experience, whether the driver has any disabilities, and road and weather conditions.

However, the technology for THC testing is more complex than the alcohol breath tests police currently use. A few hours after ingestion, THC in the body turns into molecules called metabolites. These molecules do not cause impairment but can linger in the body for a lot longer. Differentiating between active THC and inactive metabolites is not easy, especially in a handheld device.

Could there be false convictions based on faulty technology?

Thus, once the first generation of THC breath test machines does become available, it would not be surprising to learn that they are not as accurate as their manufacturers claim. Unless these devices are fully tested and reliable before they hit the streets, people in Contra Costa who use marijuana legally could be wrongly charged with driving under the influence.