"Reevaluating Marijuana Impairment: The Need for Better Driving Tests"

A Justice Department researcher suggests that states may need to reconsider using THC concentration as a basis for marijuana impairment testing for driving, as chronic and infrequent users have different THC concentrations correlated to different effects. Research has shown that THC concentration in the blood is not well-correlated with impairment for driving, prompting the need for better tests. Lawmakers and the research community have been focused on developing an objective standard to measure marijuana impairment and a related field sobriety test to ensure highway safety, but challenges remain in establishing a standardized test for marijuana impairment on the roads.