However, for me in the end I think it comes down to this: there's lots of horrible things people can do to each other, and we generally respond to that by punishing the offense.
So, although I'd like to see drugs legalized, I could also see huge taxes on certain types of drugs, at least in certain settings, or punishments for irresponsible advertising, etc.
Fentanyl to me is an interesting example, because to me it illustrates problems with drug regulation: it puts control over decision-making authority into a small group who are given unquestioned deference about those decisions. If anyone could get fentanyl, I think there would be an expectation that everyone evaluate it potentially, and that the consumer learn more about it, or get second opinions from other experts (psychologists, pharmacists, neuroscientists, biochemists). As it is, we sort of say "ok, whatever you say doc" and then ... well... we saw how that went.
Someone expressed surprise at how little the cognitive liberty argument gets raised in all of this, which I agree with 100%, but I'd take that further. What I'd argue is that I'm surprised that physical autonomy, as a health issue, isn't raised more.
To me, drug regulation and medical regulation are two sides of the same coin. The same laws that criminalize ecstasy are the same laws that prevent an experienced, knowledgable consumer from purchasing an antidepressant without a prescription.
People act like if you could get meds from whomever, or on your own, that all hell would break loose, but there are intrinsic consequences to acting heedlessly. People would figure it out fast. And to the extent they didn't, we're better off addressing it as a public health problem than a crime problem.
Taking the perspective of a business man, it's possible for drugs to be too addictive, as they have the bad side effect of killing your customers, which is bad for revenue and a PR disaster. So even if a 'designer drug' market emerged, I don't think you'd find many companies that wanted to develop something as addictive as fentanyl.
Medicine is only for sick people. Recreational drugs would potentially be for everyone. Plus, they can be made extremely addictive. It's the perfect commercial product.
New drugs already exists that are more addictive and powerful than old ones. Like Fentanyl, for instance[1]. Who knows what research labs would come up with if they threw lots of money and brain power into it?
A global legalization of drugs would be quite a Pandora's box. I'll quote Noah Harari and say it would start what he calls "the chemical pursuit of happiness" [2].
In the end, the risk is that we end up like the woman with an orgasm button[3], or turn us into some kind of vegetative state, as described in "the metamorphosis of Prime intellect"[4].
1. https://en.wikipedia.org/wiki/Fentanyl
2. https://en.wikipedia.org/wiki/Homo_Deus:_A_Brief_History_of_...
3. http://boingboing.net/2008/09/16/brain-implant-result.html
4. https://en.wikipedia.org/wiki/The_Metamorphosis_of_Prime_Int...