[cheald]

Because it makes an implicit assumption that drug use is a bad end unto itself. The problems with drugs(/alcohol) aren't that some people get high(/drunk), the problem are the people who operate heavy machinery while impaired, whose abusive tendencies exhibit themselves under reduced inhibition, who commit criminal acts in order to feed an addiction, or who are self-destructive and use drugs/alcohol/sex/video games/whatever to destroy themselves.

I would wholly expect drug use to go up under a repeal of drug prohibition. I would also expect a whole litany of dangerous behaviors and side-effects currently associated with drug use to be reduced.

[w1ntermute]

Then have the law reverse if the side effects and dangerous behavior go up.

My general point is that, when there's uncertainty as to the outcome of a change in the law, you could just have a clause in the bill saying it'll be reversed automatically if things go south. This could be applied to anything from drug laws to gun control to lower/higher taxes. Rather than sitting around guessing what might happen, just run an experiment, and reverse it quickly if things don't go well.