This boils down to a safety issue. I'd rather have the guy who is NOT a drug user running the forklift or the backhoe then the one who is. I would guess the psychological issue with drug use and hence the desire for employers to drug test is that someone willing to thwart the law for their own recreation may also have questionable ethics when it comes to company property and money. Obviously, it is not foolproof, but if Du can make assumptions that aren't always correct, then I suppose employers should have the freedom to do the same--right DU? (I won't hold my breath for that yes)