Portugual decriminalized drug use and saw decreases in drug-related crime, increased addiction program enrollment, decreased youth use of drugs, decreased drug-related deaths, and decreased HIV infection rates.
That's interesting, I'll definitely research further. It's possible these improvements were because they criminalized it in a sub-optimal way, as the US does. That is, it's possible that an optimal war on hard drugs could lead to even bigger net benefits. Imagine if no users needed fear prosecution; that's one aspect of the war I'd wage.
http://en.wikipedia.org/wiki/Drug_policy_of_Portugal