Abstract: "Understanding and addressing cannabis-impaired driving has challenges that differ from alcohol-impaired driving. Cannabis is not limited to a single drug. Recreational cannabis generally contains both Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), among dozens of other cannabinoids. The best evidence for beneficial effects of cannabinoids are for the use of CBD to treat rare pediatric convulsive disorders.6 A National Academy of Sciences panel cited substantial evidence for modest effects of cannabinoids for chronic pain, nausea and vomiting associated with chemotherapy, and spasticity of multiple sclerosis.7 However, cannabinoids used for the treatment of disorders and their symptoms are largely pharmaceutical-grade products (ie, not smoked or vaped products) that contain synthetic THC or combinations of THC and CBD. The majority of cannabis products available and used are not specific pharmaceutically prepared cannabinoids in well-studied doses, and dose labels often misrepresent actual contents. Thus, assessing cannabis exposure is complex".