California Bill Would Impose Strict THC DUII Blood Level Limits

By Keith Mansur

Oregon Cannabis Connection


AB2740 was introduced in February by Assemblymen Evan Low (D – Silicon Valley) and Tom Lackey (R – Palmdale), and it calls for a 5 nanogram per milliliter (ng/ml) Blood Alcohol limit of THC for driving under the influence of marijuana infractions. The bill would not only disregard many recent findings, it also ignores a recent commissioned study by the legislature with the Center for Medicinal Cannabis at University California San Diego.

The upcoming study, which garnered 1.8 million dollars in funding, in part due to Assembly Bill 266 and the Medical Marijuana Regulation and Safety Act, would be to develop an effective sobriety test to determine if drivers are impaired by marijuana.

THC ng/ml Chart
It is easy for blood levels to remain well over 5 ng/ml in a regular user of cannabis, for many hours after any possible impairment would have worn off. Image: CaNORML.

“We’ll bring in 50 to 60 participants and have them smoke a marijuana cigarette at different levels of THC — roughly 0, 7 and 12 percent,” explained Thomas Marcotte, one of the scientists leading the study and a psychiatry professor at UCSD to UCSD Guardian. “We’ll follow them over the course of the day on driving simulations, some iPad-based cognitive measures as well as collecting fluids, including blood, saliva and breath, to see if we can correlate those levels, objective cognitive performance, and relate those to how they do on those driving simulations.”

Also at odds with the bills strict limits are other recent studies on driving and marijuana intoxication levels. Dale Gieringer, the California Director of the National Organization for Reform of Marijuana Laws, is unsettled about the bill being introduced.

“I don’t know why they keep flogging this dead horse, especially while NHTSA [National Highway and Traffic Safety Administration] itself has recently issued an overview of the whole subject…and warned that its difficult to come up with a firm relationship between drug levels and driving impairment.” (Study is here)

Gieringer also forwarded me a study that was recently published by BMJ entitled Prevalence of alcohol and drug use in injured British Columbia drivers. Paul Armentano, the Deputy Director of Norml, sent an email to Gieringer and he pointed out the data from one notable table…Table 2.

Table 2 in this study shows the odds of an accident occurring (represented by the “odds ratio” or “OR”) for individuals with elevated THC levels. The odds ratio for ALL THC-positive drivers does show a slightly elevated chance of single vehicle crashes with an OR of 1.64. However, those with a level of 3 ng/ml show a decreased chance of an accident, with an OR of only 0.72. So, the evidence indicates the more stoned drivers were actually safer behind the wheel!

This evidence is another example of the lack of science based decisions regarding marijuana impairment. Many people for years have said they are safer drivers when they have been smoking marijuana, and maybe they were right!

Geiringer, and others, believe a drug test is no solution. Many would like to see a impairment based test implemented, if there is actually a need for any test at all.

“The best thing to do is to work on impairment tests and roadside sobriety tests,” Geiringer told OCC. “They are a much better indication of any problems than a drug test.”

What is to come of the restrictive bill? Thankfully, not a lot according to Geiringer.

“At the moment it’s hung up in the Appropriations Committee in the Suspense file…It might get out of the Assembly, but it’s not going to get through the legislature this year in my opinion,” Gieringer told OCC. “I’m sure we can beat it in the Senate.”

© 2016 Oregon Cannabis Connection. All rights reserved.

Keith Mansur

Keith Mansur is the founder, publisher, and editor of Oregon Cannabis Connection newspaper. The print publication has been serving Oregon since 2010. He has been a Oregon medical marijuana patient, grower, and caregiver since 2006. Find him on Facebook or email him at

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