Considering the whole idea behind prohibition is that drugs are bad for you, therefore you shouldn't do them - surely putting users in prison is one of the least effective ways of doing that. It's a well known fact that prison breeds criminals, even if you don't go in there a crim, you're dam likely to come out as one on the otherside.
I don't take coke, but if people know the dangers and still take it - let them. Offer them help like we do with alcohol and fags, but don't just label them as evil-doers and chuck um away in a cell for a period of time longer than you'd get for manslaughter, or even murder in many cases.
The laws f**ked when it comes to drugs, sorry, but it is.