Measuring Drug Impairment In Drivers Is Easier Said Than Done

Drug-impaired driving is a growing concern for highway safety officials. But, as a recent report makes clear, its actual impact is still difficult to measure.

The report from the Governors Highway Safety Association, a group of state highway safety offices, found that in 2015, among fatally injured drivers with a known test result, drugs were detected more frequently than alcohol.

The report was funded by the Foundation for Advancing Alcohol Responsibility, a nonprofit that advocates against drunk driving and underage drinking and that is funded by the distilled spirits industry.

If you the about the report, you might conclude that drugs are now responsible for more traffic fatalities than alcohol. But the report doesn't say that. Its findings cannot show that drugs are responsible for more deaths on the roadways than alcohol, in part because it's difficult to apply the same standards developed for measuring alcohol impairment to other drugs.