By Paul Armentano

Roadside oral fluid screening, such as that being considered by California lawmakers and highlighted in CBE Technology, is simply a detection test; it is not a per se indicator of whether subjects are ‘under the influence’ of a controlled substance.

To date, no such data exists correlating THC/oral fluid levels and/or THC/breath detection levels with behavioral impairment (such as Breathalyzer detection of alcohol at levels above .08 in blood have been correlated as valid predictors of alcohol-induced driver impairment). In fact, no scientific studies have yet to even attempt to do so.

California Senate Bill 1462, which is scheduled to be heard by members of the Senate Appropriations Committee on Monday, May 9, would authorize police “to use a preliminary oral fluid screening test that indicates the presence or concentration of a drug or controlled substance as a further investigatory tool in order to establish reasonable cause to believe the person was driving a vehicle in violation of certain prohibitions against driving under the influence of drugs.” Yet, in reality, testing positive for THC on such a test says little with regard to whether one is actually impaired.

That is because alcohol is unique among drugs in its predictability, both in its pharmacokinetics (drug metabolization by the body) and behavioral effects. As a result, the United States National Highway Traffic Safety Administration (NHTSA) acknowledges: “Toxicology has some important limitations. One limitation is that, with the exception of alcohol, toxicology cannot produce ‘per se’ proof of impairment.” So while it is possible that oral fluid/saliva testing and/or breathalyzer drug technology may pose certain potential advantages (e.g., such tests could be administered on site rather than post arrest hours later) over urine or blood specimen collection, two matrixes that are notoriously unreliable for establishing either behavioral impairment or recency of drug use, these alternatives are nonetheless unlikely to provide any direct or definitive evidence of whether or not one is driving under the influence of cannabis or anything else.

Ultimately, if politicians and law enforcement’s priority is to better identify drivers who may be under the influence of cannabis then the appropriate response is to identify and incorporate specific performance measures that accurately distinguish those cannabis-influenced drivers from those who are not, such as via the use of modernized Field Sobriety Tests, training a greater number of Drug Recognition Evaluators, or even through the use of performance testing technology such as My Canary rather than by relying on the detection of compounds that are not consistently associated with behavioral impairment.

Author’s note: Paul Armentano is the Deputy Director of NORML — the National Organization for the Reform of Marijuana Laws, and he is an advisor for Freedom Leaf Inc. He is the co-author of the book, Marijuana Is Safer: So Why Are We Driving People to Drink?The Citizen’s Guide to State-By-State Marijuana Laws> (Chelsea Green, 2013) and the author of the book, The Citizen’s Guide to State-By-State Marijuana Laws (Whitman Press, 2015).