Yeah I'm afraid that's bullshit. Your link describes an instrument that supposedly can test for THC levels. That's an entirely different thing from testing for "impairment". That can't be quantified like blood-alcohol level, which itself will vary person to person.
From the same link:
>> Furthermore, the question of “marijuana-impaired driving” is
widely misunderstood. A recent study from the National Highway Traffic Safety Administration (
NHTSA) found that high drivers are much safer than those who drive drunk. The
Washington Post summarized the study thusly: “After adjusting for age, gender, race and alcohol use, drivers who tested positive for marijuana were no more likely to crash than who had not used any drugs or alcohol prior to driving.” <<
See post 134 for what a legitimate test means as opposed to playing with a chemistry set. A roadside reflex test could identify, say, a driver who's been awake too long, a drunk, a (legal) drug reaction or anything else. Playing with chemicals is just playing with chemicals. It's meaningless..
And it's worth noting that the fascist asshole who instigated this intrusive pee test bullshit is the guy in your avatar.