Late last year, Scott Adams, creator of Dilbert, wrote a blog entry in which he mentioned drug prohibition. Right at the end of the post he mentioned the need to legalize drugs due to the financial costs of enforcing drug laws:
"Likewise, the future includes legalized (de facto or literally) drugs and prostitution, out of budget necessity. There simply won't be enough tax money to chase that sort of perp. And say goodbye to speed limits in all but the most dangerous roads."
If you've never read Adam's blog yet, check it out. It's always thought provoking, that's for sure.