You might be interested to read
this. It is a thorough, ACLU-sponsored, cost-benefit analysis of employee drug testing that contradicts the claims you make above. Drug testing is not cost-effective, and there exist several better alternatives.
dgroulx, I'm not going to get into a pissing contest with you about who knows more about the effects of illegal drugs, but you know nothing about my background in this area, and I don't appreciate your sarcasm.
Drug abuse is a major problem in this country, but a blanket stigmitization of drug users is cruel and results from ignorance.