As attitudes about marijuana change, drug-test firms brace for fight

With marijuana acceptance on the rise and more states trying to get into legalization, drug testing companies are starting to sweat. For now they are in a safe zone after the Colorado Supreme Court granted businesses the right to continue to test for marijuana because it's federally illegal, regardless of state policy. Drug testing companies seem to be the main proponent of continuing drug testing and keeping marijuana illegal, as marijuana counts for most failed workplace drug tests, claiming that marijuana users miss more work, cause accidents, and cost employers money. Testing positive for marijuana, or anything for that matter, does not prove the drug was used at work, or even in the last few days, and the few studies that have been done on the subject show that marijuana causes no more problems in the workplace than alcohol. 

“A positive drug test provides no information on when an illicit substance was used, how often or how much is typically used, or if the person was or has ever been impaired at work,” he said