Every month, the team at Hound Labs hears from a growing number of police departments that want to know when its marijuana breathalyzer will be ready for use on the roadside. Dozens of departments across California have volunteered to participate in the company’s pilot tests. Hound Labs aims to help resolve one of the biggest concerns among law enforcement about the recent legalization of cannabis: There’s still no reliable way to determine if a person is too high to drive.

“We, the police in California, were hoping to have a scientific approach if we were going to legalize; a machine where we could say, ‘OK, you have this much marijuana in your system,” Lompoc Police Chief Pat Walsh says. “The legalization came before the solutions to those types of questions.”

The standard protocol among the Los Angeles Police Department is to take a blood sample from drivers suspected of consuming cannabis. The problem with this is that it’s widely accepted among toxicologists, including those in Orange and Los Angeles counties, that THC can stay in the body for days after a person is no longer intoxicated. Still, data from blood samples can be presented in court to prosecute for cannabis DUIs.

“Depending on the jurisdiction, there are district attorneys and city attorneys that believe any amount of THC is conclusive evidence of impairment,” says Nick Morrow, a retired Los Angeles County Sheriff deputy who now testifies in court as a DUI expert.

Most of the time in L.A. County, Morrow says, people facing cannabis DUIs are in front of juries who “are just as confused as everybody else out there” about whether THC found in the blood of a driver should even be considered relevant. It’s not illegal to consume cannabis and drive, Morrow points out. It’s illegal to consume cannabis to the point of impairment and drive. And currently, there’s little known in the scientific community about the relationship between THC levels in the body and intoxication.

Jenny Lynn, Hound Labs co-founder, says her company’s marijuana breathalyzer is an important first step in collecting the data necessary to do this. She says there’s sometimes a misunderstanding that the device will be able to tell law enforcement whether someone is too high to drive. As of now, the tests Hounds Labs has done with volunteers merely detect whether a person consumed cannabis within the last few hours. They also consistently show a relationship between how much cannabis a person consumed and the magnitude of the reading, displayed in picograms. But, unlike with alcohol, there are too many unknowns about how cannabis is processed by the brain to assume that the amount of cannabis a person consumes directly correlates with how impaired he is. The same amount of cannabis, for example, could potentially affect the driving of a regular smoker and a first-time user very differently.

“Can we answer right now how much is too much? No, we can’t. But we know this device will allow for that research,” Lynn says. “We’re going to be able to start to provide scientists with data to do those correlation studies with impairment.”

Conclusive evidence will likely take further research. Until then, Lynn says, the breathalyzer will still help promote more fairness in the criminal justice system by giving a more reliable reading of when a person consumed cannabis. Hound Labs will verify its results in clinical trials at the University of California, San Francisco, this spring, and aims to have the device available for use by law enforcement at the end of 2017. “The number of people who want to participate around the country in pilot tests is already more than we can support,” Lynn says.

Police Chief Walsh was one of the first people to reach out to Hound Labs about the marijuana breathalyzer. He says he’s excitedly awaiting an update from the company. For now, he’s been investing in more training for his officers to recognize when someone is too high. He says it’s difficult, though, because the courses are expensive and time-consuming. He likely won’t be able to train everybody in his department as soon as necessary. “Like all the things we do, we adjust and improvise and we figure it out,” he says. “That’s why I’m interested in the marijuana breathalyzer.”

Advertising disclosure: We may receive compensation for some of the links in our stories. Thank you for supporting LA Weekly and our advertisers.