The rush to invent the first breathalyzer for weed

Woman performs sobriety test in front of a copy in the dark on the side of a highway
Colorado State Troopers perform a road side sobriety test. Photo: Andy Cross / Getty

With states continuing to legalize or decriminalize marijuana, scientists and entrepreneurs are rushing to invent a marijuana breathalyzer that would detect whether someone was impaired while driving, according to STAT, instead of relying on more subjective sobriety tests.

The key problem: While urine and blood tests can show whether someone has used marijuana, they can't test impairment. While some states have set a legal limit of THC for drivers, some experts say that frequent smokers could pass the THC level without actually being impaired, according to STAT.