I understand the darwinian approach or the libertarian but its a tough call either way. Any thing is worth a try at this point in time.
What we are doing now is a failure IMO.
I'm not even approaching it from a Darwinian stand point. You just have to ask yourself "Why are they illegal?" If it's because the drugs pose a risk to the consumer, that's not really a good reason for it to be outlawed. Like HempHead said, you either own your body or you don't.
If it's because the consumer might do harm to others, then it's still not a good reason for it to be illegal, because the harm they MIGHT do is already punishable under law.
Drugs laws are really unnecessary and expensive.