Driving Performance

Study: Cannabis’ Influence On Driving Performance Differs Significantly From That Of Alcohol

Cannabis-influenced driving performance is significantly different from alcohol-induced driving behavior, according to driving simulator data published in the Journal of Applied Toxicology. “THC concentration-dependent associations with decreased speed, increased time below the speed limit and increased following distance suggest possible awareness by drivers of potential impairment and attempts to compensate,” authors concluded. “The compensatory behavior exhibited by cannabis-influenced drivers distinctly contrasts with an alcohol-induced higher risk behavior, evidenced by greater percent speed.”

Safe Driving

Federal Study: THC-Positive Drivers Not More Likely To Be Involved In Motor Vehicle Crashes

Drivers who test positive for the presence of THC in blood are no more likely to be involved in motor vehicle crashes than are drug-free drivers, according to a federally sponsored case-control study involving some 9,000 participants. The study, published Friday by the United States National Highway Traffic Administration (NHTSA), is the first large-scale case-control study ever conducted in the United States to assess the crash risk associated with both drugs and alcohol use by drivers.

Arizona Marijuana Laws

Arizona: Supreme Court Rejects DUI Per Se Standard For THC Metabolites

The Arizona Supreme Court this week rejected a 1990 state law that classified the presence of inert THC metabolites in blood or urine as a per se traffic safety violation. The Court concluded: “Because the legislature intended to prevent impaired driving, we hold that the ‘metabolite’ reference in § 28-1381(A)(3) is limited to any of a proscribed substance’s metabolites that are capable of causing impairment. Accordingly, … drivers cannot be convicted of the (A)(3) offense based merely on the presence of a non-impairing metabolite that may reflect the prior usage of marijuana.”