In a recent article in the New York Sun, Tom Marcotte, PhD, co-director of the Center for Medicinal Cannabis Research at UC San Diego, is prominently featured for his expertise on cannabis-impaired driving. He underscores the central scientific challenge facing states: unlike alcohol, THC blood levels do not reliably correlate with behavioral impairment, therefore they are not helpful in identifying impaired driving. Dr. Marcotte explains that THC declines rapidly in the bloodstream, varies widely across individuals, and may be detectable long after impairment has resolved—especially among frequent users—making “per se” legal limits scientifically unreliable. He also cautions that emerging roadside technologies, including breath tests and oral-fluid assays, have significant limitations and are often adopted before being validated. His insights reinforce the need for evidence-based policy and rigorous research to guide public safety decisions.
Read the full article here.