A new Congressional Research Service report on marijuana and motoring found that the presence of THC in a person’s blood is an inconsistent predictor of both driver impairment and performance.
The report mentioned: “Research studies have been unable to consistently correlate levels of marijuana consumption, or THC in a person’s body, and levels of impairment,” NORML stated. “Thus, some researchers, and the National Highway Traffic Safety Administration, have observed that using a measure of THC as evidence of a driver’s impairment is not supported by scientific evidence to date.”
The report’s findings are consistent with a study by the National Highway Traffic Safety Administration.
“There is as yet no scientifically demonstrated correlation between levels of THC and degrees of impairment of driver performance, and epidemiological studies disagree as to whether marijuana use by a driver results in increased crash risk,” the report concluded. “Based on current knowledge and enforcement capabilities, it is not possible to articulate a similarly simple level or rate of marijuana consumption and a corresponding effect on driving ability.”
Illinois, Montana, Nevada, Ohio, Pennsylvania, and Washington enforce various laws for the presence of certain amounts of THC in blood. Arizona, Delaware, Georgia, Illinois, Indiana, Iowa, Michigan, Oklahoma, Rhode Island, South Dakota, Utah, and Wisconsin enforce zero-tolerant laws.