zero pass/fail
A zero limit seems fine untill you realize the minute levels the tests can detect.
One extreme example of this was the Winter Olympics in Nagano where a Canadian was stripped of his medal for a trace of THC in his system.
The guy was a well known non smoker, ( for a boarder in Whistler to be a non smoker was such a rarity that this was well known around town). It seems that just being around smokers was enough to leave a trace in his system.
I personally got jammed up as I was told that I needed to update a drug test on re visiting a construction site. Problem was I had being prescribed 222's a few weeks previously and was certain to test positive for cocaine. I managed to duck the test but I would have refused it if need be. There was no way I was going to have a piece of paper floating around with a positive test result no mater what the reason.
Drug testing is attractive as it seems an easy fix to a complex problem. Like most such "solutions" it is neither easy or a fix.
20driver