Middlefork, I have little sympathy for the addict and absolutely none for the dealer. But you have to ask yourself why are so many people doing drugs in the first place?
Does incarcerating people arrested for possession really help the problem or just pack the jails? How do we as a society teach people they CAN take control of their circumstances? Alternatively, how does a society teach people their actions DO carry consequences?

I think the combination of personal responsibility and the risk of dire consequences hold the key.

Heck, I'm just the veterinarian, not a sociologist.