The idea that anyone has the right to regulate someone else's life based on morality is deeply puritanical. It may seem like a different problem when posed in the form of a highly addictive and often destructive behavior such as meth use but it's still the same fundamental issue.

How much harm does being homeless do to society? How much harm does having a bad credit score do to society? Smoking cigarettes? Listening to thrash metal? Rock climbing? Eating a cheeseburger? Being HIV positive? What's the proper response to these sorts of things?

History has shown us in no uncertain terms that it is impossible to protect people from themselves. And every attempt to do so will fail utterly. Will result in more harm to the individual and more harm to society than the problem attempted to be addressed. There are good ways and bad ways to deal with the problems that, say, meth addiction creates. The wrong way is to try to regulate what people can put into their own bodies, that road leads to addicts who can't seek help because of fear of jail, it leads to no-knock militarized police raids, it leads to a criminal justice system increasingly cut-off from the populace. It leads to corruption, to gang violence, and to tragedy of epic proportions. There are too many examples from history to pretend otherwise.

P.S. http://www.imdb.com/video/screenplay/vi3582329113/