Close to two-thirds of the drivers who were killed in highway crashes and tested for drugs afterward had opioids, marijuana, or some combination of the two in their bodies, according to a new report on driving drugged in the United States.

That number is likely to increase as more states move to effectively legalize marijuana while struggling to find ways to detect its active use in motorists.

With legislation to legalize recreational marijuana pending in 21 states, the new Governors Highway Safety Association report urges states to move faster toward developing reliable roadside testing devices and providing better training for law enforcement to detect drivers under the influence of such drugs. That’s because studies and federal crash data suggest that more people are getting behind the wheel after getting high.

Thursday’s report, using a February 2018 survey and other data, admits the science on whether legalizing marijuana has contributed to higher crash rates is not settled.

Tests that detect marijuana’s active ingredient, THC, don’t always do so in a way that reflects whether a person is impaired, as traces of THC can remain in the system long after use and individual tolerance varies widely. But the group says it is reasonably certain to believe that marijuana has contributed to the causes of some crashes and increased the risk of driving for some motorists.

WASHINGTON POST