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Driving Stoned: How Much Is Too Much?

A San Diego woman, who does not want to be identified because she smokes marijuana daily in her San Diego apartment, says she is a better driver when she is stone, May 18, 2017.
Matt Bowler
A San Diego woman, who does not want to be identified because she smokes marijuana daily in her San Diego apartment, says she is a better driver when she is stone, May 18, 2017.

This is the first of a three-part series on drugged driving. Click here for Part 2 and Part 3.

Driving While Stoned

Every day when this San Diego woman gets home from work, she likes to sit on her couch, and light up a joint.


“It’s almost become a habit. Like, I don’t even really think about it," she said. "It’s just something that’s part of my daily routine. I mean, I still feel it. It definitely makes me feel more relaxed.”

She gets stoned at work, too. She asked us not to use her name because she does not want her boss to know about her marijuana use.

She says she often drives when she is high. She says it helps her drive better.

“So, usually when I’m sober, I’ll be a little bit more impatient, I’ll have more road rage, and I’ll be more aggressive," she explained. "But, while I’m stoned while driving, I’m more inclined to let people pass, you know, and give them the right of way, or, you know, take things a little bit slower.”

According to a 2014 survey on drug use and health released by the Substance Abuse and Mental Health Services Administration, 10 million Americans admitted to driving under the influence of illegal drugs.


Drugged Driving Is Dangerous, Prosecutors Say

At a public forum in Escondido on drugged driving, San Diego Deputy City Attorney Taylor Garrot shows the audience a video of someone driving under the influence of marijuana. The video shows a jeep at full speed smashing into a car in front of it.

“This is an actual marijuana DUI," Garrot said, pointing to a screen in the front of the conference room. "So this car stops at the yellow and then red lights, and then the jeep comes barreling in there. That was only marijuana, there were no other substances on board.”

Driving Stoned: How Much Is Too Much?

Garrot is part of a team of prosecutors which files cases against drivers impaired by drugs other than alcohol. A lot of his cases involve drivers who use marijuana by itself, or in combination with prescription drugs like Xanax. Garrot said a lot of people do not understand that drugs interfere with one’s ability to drive.

“Drugs are similar to alcohol. Alcohol is a central nervous system depressant," he explained. "Prescription drugs, often times, have the same or similar effects as alcohol. Marijuana can have the same or similar effects of alcohol.”

And with retail sales of marijuana coming next year, there will likely be a lot more Californians driving under its influence.

California Department Of Public Health

And what will that mean?

Jaynia Anderson, a research scientist with the California Department of Public Health, is looking into the recent past for clues.

She works with the Crash Medical Outcomes Data Project.

California Department Of Public Health

“So, we’ve looked at fatal collisions over the past 10 years, from 2005 to 2014, and the most common drug found in these drivers was marijuana," Anderson said.

Anderson points out that does not mean marijuana was the cause of the crashes. And the data does not necessarily indicate that drivers were impaired by the drug.

No Legal Limit

There is no legal limit for marijuana impairment in California. In other words, the state does not have a standard that determines when a person is deemed too stoned to drive safely.

Colorado and Washington were the first states to legalize marijuana. Both have adopted the same legal limit for drivers: five nanograms of THC per milliliter of blood. THC is the psychoactive compound that gives marijuana users a high.

Dr. Igor Grant, director of UC San Diego’s Center for Cannabis Research, has launched a study that aims to scientifically establish a standard level of marijuana impairment for drivers.

He thinks Colorado and Washington jumped the gun.

“In my view, it’s premature to use these per se limits," Grant said. "That’s not to say that if you are using marijuana, you are safe to drive, necessarily. But we don’t know what that limit is.”

Dr. Michael Sise, chief of staff and senior trauma surgeon at Scripps Mercy Hospital, believes when it comes to driving, there is no safe level of marijuana use.

He has seen the results of too many drug-impaired crashes to think otherwise.

“Any kind of drugs or alcohol wipe out that ability to react quickly, to judge distances, and in fact make you a dangerous driver,” Sise said.

Driving Stoned: How Much Is Too Much?
As California gears up for retail sales of marijuana in 2018, police are concerned about what more pot use could mean for highway safety.

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