Cannabis and Cars

DUI attorneys and scientists convene in Los Angeles to share expertise in Marijuana-related DUIs

“Cannabis and cars” was the topic at the January 2016 conference of the National College for DUI Defense in Los Angeles, convening at Marina Del Rey. The focus of the seminar was to educate DUI defense attorneys who represent drivers accused of impaired driving in cases involving cannabis and other drugs.

George Bianchi of Seattle, former dean and now a fellow of NCDD, presented his paper on cannabis and cars. The work he authored is replete with a formidable library of recent scientific research and case law. Scientific and legal issues that are specific to the absorption and elimination of delta-9 tetrahydrocannabinol from the bloodstream are being raised in courtrooms throughout the United States.

The relationships of THC, impairment and driving ability are critical where the state brings criminal DUI charges. Bianchi stated, however, “There is no true understanding and agreement about the absorption and elimination of THC.”

And, although the main isomer and psychoactive constituent of marijuana remain active for a short time, studies have confirmed that metabolites of THC that have no psychoactive effect. However, these metabolites may remain in the system for 30 days or more. The presence of "11-nor-9 carboxy" delta-9 tetrahydrocannabinol may be offered to prove that a subject ingested THC at some time in the last month -- but it doesn't prove (or tend to prove) that a person is presently impaired.

In 2014, Bianchi asked for help in his THC research from Ted Vosk. Bianchi asked Vosk to review 23 articles that related marijuana impairment to specific THC levels.

Vosk completed the review and of the 23 articles found only four that seemed to advance some sort of per se level of impairment for THC. (Two other articles promoted zero tolerance.)

Bianchi wrote about tests in 2014 involving drivers who had consumed both alcohol and marijuana. Subjects gave blood and saliva samples as they took driving tests on simulators. Scientists concluded that they had observed something they called “lateral position lane weave.” They got excited about factors such as "steering angle," "lane departures" and "minimum and maximum lateral acceleration" with their "driving simulator."

The remainder of the study's conclusions set forth quantitative data about possible relationships between active, post-dose effects of THC with “minor lateral decrements” observed, which, one writer stated, “may be dangerous in narrow or winding roads.”

The standards for marijuana and driving currently are all over the place, depending on the state (meaning, the jurisdiction) you're in. But, in the meantime, police are being trained to continue to use the old, standard alcohol tests in looking for “clues” that a driver is “impaired” by marijuana.

In every presentation at this conference, it became clear that police and district attorneys nationally are staking out their positions on when, and at what levels, THC impairs driving ability.

In the meantime, in states where medical and recreational marijuana use is legal, marijuana users are getting DUIs.

And, in all states, drivers are getting DUIs where they have given a breathestimate of their blood alcohol of less than .08 percent but provide some evidence that they also had used marijuana.

NCDD has over 2,000 members nationwide.