With recreational cannabis use legalized in around half of the states in the U.S., the need for a reliable intoxicated driving test has arisen. While there are objective measures to test for alcohol impairment, like the breathalyzer, police officers currently use subjective tactics to test for marijuana impairment.
In an editorial published in the Journal of Studies on Alcohol and Drugs, Rutgers adjunct professor William McNichol argued that the current methods that police officers use to detect marijuana-impaired driving are based on pseudoscience and need to change.
Law enforcement currently follow a standardized protocol to detect drug impairment, after being trained by Drug Recognition Experts (DREs) and Workplace Impairment Recognition Experts (WIREs). These roadside tests include tests of physical coordination, looking at pupil size, and more.
RELATED: This federal police force is now safe to consume weed off-duty
However, McNichol argues that these protocols have no scientific basis and have never been tested through scientific study.
“Both DREs and WIREs claim that their expert opinions on the question of impairment are objective, reliable, and grounded in science, even though the procedures they use were never designed to detect impairment and do not do so,” McNichol wrote.
One example is the muscle tone test. DRE protocol says that muscle tone is an indicator of marijuana impairment, and thus, police officers are trained to squeeze a subject’s limbs to identify whether their muscle tone feels normal or not. However, healthcare professionals do not measure muscle tone by squeezing a limb, nor would they recognize this as a valid method of measuring muscle tone.
RELATED: Legal limits for cannabis-impaired driving may be impossible, THC impacts people differently
However, a prior study that was published in the Journal of Analytical Toxicology found that DRE’s determination of impairment was consistent with the administration of the drug in 76 percent of cases, illustrating the potential effectiveness of DRE tactics.
Marijuana DUI test efficacy has long been debated. Unlike alcohol, which has a strong correlation between impairment and breath or blood alcohol level, THC can stay in a person’s system for hours, even days, after they are no longer high, making it difficult to determine the level of a person’s impairment.
As researchers and scientists work to create new, more reliable methods of testing for marijuana impairment, many states are piloting different roadside tests, like saliva tests and goggles that measure pupil size, due to concerns about the accuracy of DRE protocols.