For the sake of argument, lets say you decriminalize all currently illegal substances, to include everything not FDA approved. Lets say you turn it over to the free market, and tax it as you would say any other natural product, like groceries. Lets roll alcohol and tobacco in there too ... no more special government taboo against them. As products they become value neutral; we're less concerned about the products themselves. However, those who use them in such a manner as to harm others will be arrested accordingly. [Is that not similar to some arguments I've seen here against gun control? Its the criminal not the tool that we should focus on?]
So let's imagine the worst case scenario happens: there is a spike in drug related hospitalizations and death, particularly amongst our young people. In keeping with the spirit of the argument, so what? Name one part of life in which I should be protected from the consequences of my actions, informed or otherwise? Are there already laws in place in reference to crimes committed against others? Would those not already encompass any crime someone might commit under the influence of drugs?
Of all the arguments I've heard in favor of decriminalization, that is the strongest. Arguments about generating revenue, or reducing costs, or medical benefits, or just one drug but not another ... meaningless. It all really boils down to what is the role of the government. If you believe it is to protect us from ourselves, then lets outlaw everything. If you believe it is to protect us from each other, then we've got way too much law written already.
And if a community decides to make something taboo, then let them - no laws necessary for that. I think swearing in front of women and children is offensive; there are no laws against it, but I'll confront you if you do it. So they may decriminalize drugs, but I won't hire you, recommend you for any position of responsibility, ride, hunt or shoot with you, trust your judgment in any circumstance or conversation, if you're a user ... same as an alcoholic. I think character was sufficient for most things back in the day before our present litigious society emerged.