There's a government program that's been in testing for a couple years in Britain that gives heroin to heroin addicts. They started the testing with heroin, but plan to move it to other drugs.
The idea behind it was that it's cheaper and safer for the government to supply the addicts pure heroin than it is for them to get it on their own where they'd end up stealing, beating, or killing people for money to buy their fix, and at the same time getting impure drugs in the process. Not only that, but it keeps them and others out of the emergency room if the process is controlled.
Last I heard, it was pretty successful. Of course, to be on that program you must eventually work yourself off the addiction, but it seemed to be saving the country money and crime rates dropped at the time I read the news article.
I'm not saying I approve of paying for people's fuck ups or that people won't abuse the system, but in that one instance it did prove to be benefiting the country as a whole.