proves nothing regarding its effects on the user at the time of the test. Marijuana stays in the system for a month after its euphoric effects have subsided, therefore making test results moot. Drug testing for marijuana is a bludgeon used to harass users and is only used as a threat for the purpose if inflicting punitive measures.
Texting and driving is far more dangerous than drinking and driving and smoking reefer and driving. Do I think driving stoned is a good idea? No. But to attach marijuana testing to driving safety is a straw man argument. There are tests that can determine whether a driver is impaired, and that kind of testing would go a long way to making us safer.
How many drivers of over the road large vehicles drive while fatigued? That I can't answer, but I was hit from behind by one and seriously injured. My guess is he could pass a marijuana urine test but failed a driving while fatigued test.
The root of marijuana demonization goes back to William Randolph Hearst who wanted to protect his wood pulp based newsprint monopoly. His only threat came from hemp based newsprint and he used his media dominance to launch a campaign to criminalize marijuana. He found a willing accomplice in Anslinger who feared his own daughter was going to be victimized by Negro marijuana users.
The whole marijuana criminalization is rooted in fear, bigotry, myth, superstition and greed. It's time for America to grow up. We've squandered enough resources and ruined far too many lives on this witch hunt.