Ah, but who's going to make those determinations, and on what sort of foundation? Just as with the the first drug prohibitions in this country & all the others, everyone is going to chime in with their particular brand of expertise. You can't make it just a matter of science, it is cherry picked as much as anything (global warming). If you've read all of this thread you know there are folks going around saying drugs cause evil spirits to enter the mind and every bag of smack has it's own little spook inside waiting to unleash the next Charles Manson. You know there has to be some kind of hook and the interracial sex thing isn't going to play so well next time around. So, easy enough to say there's plenty of hokum and not much of substance to justify restraining an individual who hasn't caused any harm.
At the same time you can look at something like meth (for example - surely not the only "bad" thing but one about which I have some personal knowledge) and make a reasonable assumption that, if legal, it would be very cheap and even when addicted a person can be functional and hold a job, and have no trouble buying all he wants on his honest living. But the time comes with so many (and I personally know a good number of them) where social function and the ability to earn a living kind of slips away, and they enter a downward spiral. Three of my closest friends growing up are dead because of it (suicides all) and along the way they did not leave their loved ones unharmed.
So on this thing and all the others you need to decide what to do. A no tolerance ban, personal use but no trade, start throwing down sanctions somewhere between functional and criminal, or just wait for the crime? I wouldn't think it heartbreaking if they'd just spin out & jump off the bridge, but along the way they have spouses being knocked around, kids being neglected, parents being robbed and so on. And unless you have another thing we libertarians dislike, that cradle to grave family monitoring certain groups of folks would love to see, nobody is likely to know these things are happening 'til they have gone on a while.
Now if you've read much of what I've posted here you know this whole theme of conflict and pitfalls keeps springing up, and I don't pretend to have the perfect solution, but IMO it'll need some consideration beyond what you've listed.
Absolutely. What I wrote wasn't meant to be an actual policy that could be readily implemented in real communities, but rather a sort of theoretical starting point in trying to find a solution that appeals to both libertarians and conservatives.
The objections you raise are quite valid and I anticipated a few of them even as I was writing my post. Since it is ultimately up to the voters to determine which drugs meet the dangerousness or addictiveness thresholds, there is a strong possibility that people will vote based not on actual science but rather on their fears and prejudices. Still, I think it would be an improvement to at least nominally recognize that government authority over drugs shouldn't be limitless, as most people seem to believe. It's kind of like how Congress treats the Constitution. They do all kinds of inappropriate things under the flimsy authority of the Interstate Commerce clause, but it's better than what we'd get if they could just legislate whatever they wanted without even the weak restraints of the Constitution.
You also bring up a good point about drugs that don't neatly fit into either of the two categories but still have the potential to cause harm to innocent people. I don't have a good answer for that problem either. All I can say is that no policy, not even total prohibition, is going to stop people from ruining their lives and hurting their families because of addiction. I do think that under the policy I described, fewer children would be killed in gang shootouts, or lose a parent to the criminal justice system because of a relatively harmless drug, or be exposed to dangerous criminal types who run the drug distribution networks in their neighborhoods. On the other hand there would be some parents who start using dangerous drugs under my more liberal policy when they might not have before, and their kids would suffer. But I can't imagine that too many more parents would start taking meth if by some chance their community decided not to prohibit its use.
So yes, my policy needs a lot of polishing. But does it seem acceptable at least as a starting point?