Unfortunately I'm late to the game on discovering Jamie Whyte, the British philosopher. He has a deep understanding of economics and is witty to boot. Try this 2006 column:
Drug users are simply people for whom the pleasure outweighs the risk of death, illness, addiction and all the rest. In other words, they are people for whom the benefits of drug use exceed the costs. They wouldn’t be drug users otherwise. The same is not true of everyone. Some value health more and pleasure less. For them, drug taking would deliver a net loss. Fine: these people would not take drugs even if they were legal.But addiction and asymmetric information are grounds for a powerful market failure, are they not? Yes, and Whyte handles this problem deftly:
But underestimation cuts both ways. People might fail to do something that is good for them because they underestimate the benefits. Those who have never taken Ecstasy might not know how wonderful it feels. Should it be made compulsory to eliminate this risk?There is a simpler case against an outright ban, but it requires an economic argument Whyte doesn't have the space to make in a brief column. To minimize utility loss, the proper response to a case of asymmetric info with high costs is not to ban or regulate but simply to provide the info. Inform the citizens how dangerous and addictive drugs are and they can decide the rest. Of course, the government does spread information about the dangers of drug abuse, but, as in the case of compulsion, misinformation cuts both ways. If the government spreads lies about drugs, this will lower utility as well. Utility is only maximized if government propagates the correct information about the dangers of drugs--that is, if it actually eliminates the case of asymmetric information rather than swinging it the opposite way.
And, seeing as the government spreads lies and misinformation about the dangers of drug use*, it's fair to say that no aspect of modern drug prohibition is justified on efficiency grounds. The other grounds, as Whyte well explains, are basically rubbish.
Unfortunately, Whyte concludes with a mistake:
I suspect that something similar makes legislators systematically discount the benefits of drugs. It is not enough that people value something. To count it as a benefit, our betters in Westminster must deem it worthwhile. And, as with kinky sexual gratification, they do not consider getting high to be worthwhile.On the contrary, politicians have shown time and again that they are big fans of drugs. I don't disagree that bigotry dominates drug laws, but it isn't the bigotry of elected officials. It is the bigotry of the voting public.
It is not concern for our welfare that explains the illegality of drug use. It is bigotry.
*Don't believe there is misinformation in anti-drug propaganda? Ask yourself how addictive you think various drugs are based on government advertisements, then check the real numbers for yourself. If you significantly overestimated, congratulations, you are imperfectly informed such that you may be missing out on some wonderful utils!