I've become a bit more pragmatic over the years. Having witnessed the harm people do to themselves and others by way of their addictions, whatever they may be, I'm just happy when they stop. If and when they accomplish that, I see little point in incarcerating them.
I do, however, like the idea of holding the possibility of prosecution over addicts' heads to give them additional incentive to stay stopped. In New York, this frequently is done by way of Adjournment in Contemplation of Dismissal (ACD), which basically puts the case on a back burner for a period ranging from a few months to a few years. If the defendant stays clean for the requisite amount of time, the charge is dismissed.
As for weed... frankly, I think prosecuting casual marijuana use is a massive waste of resources. I also think physicians should be allowed to prescribe "recreational" drugs, and pharmacists to dispense them, as is done in several other countries. Again, my reasons are mainly pragmatic. Most illegal drugs are very cheap to manufacture. Their street prices are vastly inflated because of the risks inherent in being in that business, and it's those inflated prices that are at the root of much drug-related crime.
If, say, heroin were legally available, it would cost about $5.00 a day to keep an addict fixed, thus reducing crimes committed by addicts to avoid withdrawal. It would also take the profit out of the illegal drug trade, thus reducing the number of innocents who get caught in the crossfire of drive-by shootings. (I have a hard time imagining rival pharmacists shooting at each other in the streets.)
Quite simply, I would like to see drug policy handled by the medical profession rather than the law enforcement community. The societal costs of the "war on drugs" are staggering, and it really hasn't been all that effective. My personal opinion, based on my own observations and experience, is that it's time to try a different approach.
-Rich