The basic problem is the police waste time and resources going after the user rather than the dealer and the distributor.
Negative.
It is a supply/demand problem. As long as there is demand, there will be supply. That is absolute. No matter what, as long as Americans demand drugs, someone will take the risk to deliver the drugs. If there was no demand, you could have dealers on TV selling their wares, and no one would buy. The end result, no dealers.
If you make it where you chomp supply, the price goes up. With production costs being more-or-less the same, the incentive to supply the drugs goes up.
If you are going to have a WoD (and I believe it is silly and destructive) try to dry up demand. Being that you can't on an addictive substance, you need to take the profit out of supply, by increasing competition.
One of the realities is that people will get high. Our gov't is only cutting the suppliers to keep costs high.
Why? Many theories abound, but there is one that keeps resurfacing. The gov't imports drugs and sells them. You can read all about it in various FR posts. Clinton and Mena is one of them. Many believe that GHWB and Clinton both were part of the operation.
Welfare money is appropriated by Congress. The urbanites spend it on drugs (where do you think the money comes from?), some black-budget operations raise money with drugs sales, or so the theory goes. The end result is money is moved from the productive sector, to the unproductive sector, to some shadowy parts of our gov't.
Poisoning the cocaine and heroin supply would have made it unwise to use the stuff. The stupid people who used might have had a 10% chance of a legal dose.
Is this any different than abortion on demand? The drug user has a choice. The unborn baby has none!
The money saved on police and prosecutors might have paid for universal free health care.
What is the moral choice?
I'm sure the police unions would scowl at a plan that would greatly reduce the need for members.