High on the highway: UCSD to develop marijuana test for CHP

Brandon Short | Contributor

Drunk drivers are not the only problem in California. An increase in drivers high on marijuana, including college students behind the wheel, has the state looking for a solution.

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UC San Diego has been given the task by California legislators to develop technology that will detect whether drivers are under the influence of marijuana. The legislators have allotted $1.8 million dollars in research money to the university.   

UCSD researchers plan to use driving simulators to study people’s behavior while impaired by marijuana. They hope to create a sobriety test that an officer could administer with a device, such as an iPad, to a possible suspect.

As of now police can immediately and scientifically measure blood alcohol levels (BAC) of drunk drivers by using breathalyzers, but they don’t have the same ability to accurately identify stoned drivers. The breathalyzer test to determine BAC calculates how much alcohol is in the same portion of exhaled air by an individual.   

The problem with detecting marijuana is that tetrahydrocannabinol (THC), the chemical responsible for most of marijuana’s psychological effects, remains in a person’s body for a week or more after using the drug. As a result, a driver could test positive at a roadside stop days after a high, wrongly convicting them of being under the influence at that time.

The legalization of marijuana, which is gaining ground steadily throughout the country, will create the need to develop a roadside tool to detect impaired drivers.   


Junior Matt Kirk shared his concerns for driving under the influence of marijuana after being personally affected.

“I believe there needs to be a sobriety test for marijuana because one of my friends was in a car accident and his reflexes were slow due to him being high,” Kirk said.

According to NBC News, states like Colorado and Washington, which have legalized marijuana, have seen a large spike in people driving under the influence. The smallest amount of marijuana can impair a driver’s reaction time. The legalization of marijuana in these states has had a huge impact on public safety.     

Junior Karen Leparulc thinks that driving under the influence of marijuana has serious consequences and needs to be treated accordingly.

“There needs to be an easy sobriety test when it comes to smoking weed,” Leparulc said. “I’ve heard many people say they are not affected when they smoke and drive. Marijuana, like alcohol, will impair your driving and needs to be treated with the same consequences.”

The current trajectory of marijuana legalization in America is bypassing scientific research. Marijuana research is subject to all kinds of regulations because it remains listed as a Schedule 1 drug by the Controlled Substances Act, written in 1970. It can take as long as 18 months for scientists to obtain federally sanctioned marijuana to run experiments.

Currently law enforcement officers in California have three standardized field tests for assessing whether a driver is under the influence of marijuana. If an officer believes a driver is driving under the influence of marijuana, they can run the Horizontal Gaze Nystagmus Test, Walk and Turn Test, and the One Leg Stand Test.

The Horizontal Gaze Nystagmus Test is when an officer moves their finger or a pen in front of a person’s face to look for involuntary jerking of the eye. The National Highway Traffic and Safety Administration (NHTSA) estimates that this test is 77 percent reliable.

The Walk and Turn test has a suspect walk a straight line while the officer looks for a loss of balance. The NHTSA estimates that this test is effective 68 percent of the time.

The One Leg Stand Test will instruct an individual to raise his or her foot, hold still, count, and look down. The officer is observing swaying or hopping. The NHTSA believes this test is 65 percent accurate.

Because these tests have relatively low accuracy compared to tests for blood alcohol content, most lawyers can have their clients escape conviction for driving impaired under the influence of marijuana.

Most lawmakers and police officers are in consensus that any amount of marijuana consumption puts you at risk of driving impaired ,according to interviews by National Public Radio.

This year California voters will have the chance to legalize marijuana, which would make it the third state in the United States to allow its residents to purchase the drug recreationally. Though that would take effect within months, the research being done at UCSD to develop a reliable field test for marijuana will take about three years. Until the studies are completed, USD students should be aware that being high impairs driving and can result in charges for driving under the influence.