The physical and mental health problems and associated healthcare burden.

This is not insignificant and totally shrugged off by the "pro-legalisation" side of things.

People keep saying "prohibition didn't work" but I'm hard pressed to find a conclusive paper on the subject. Perhaps you could enlighten me?

Edit: Ask for proof/sources = down vote. Hey everyone, fuck science.

That's oversimplifying; couldn't we drastically reduce the number of automotive deaths by outlawing driving?

Marijuana isn't an absolute evil with no redeeming qualities, and prohibition brings along a bevy of its own problems. So then we're really talking about which method, legalization or prohibition, is better in the aggregate.

When I say that prohibition doesn't work, I'm talking literally; something like a third of people in the US have smoked marijuana, and a sizable percentage (including me, a productive salaried software developer) smoke regularly despite the potential legal ramifications. I've gone on vacation with no connects and found a dealer inside of a day, which is to say that no one who wants to smoke is being stopped by prohibition.

When you take that with all of the bad things that prohibition causes, I don't know how you can rationalize its continuation.

Sure, but prohibition isn't prevention.

> People keep saying "prohibition didn't work" but I'm hard pressed to find a conclusive paper on the subject.

Assuming, arguendo, your suggestion that there is no conclusive evidence on the effectiveness of prohibition, then, given the money, lives, etc. that have been expended on prohibition, the absence of conclusive evidence of its effectiveness is, itself, a pretty strong reason not to keep tossing lives and treasure into that pit.

in other words, by any rational measure, it's a risk worth taking.

Well, today we already have those costs, plus the even larger costs of law enforcement. The choice is not between "pot is illegal and nobody uses it" and "pot is legal and it causes social problems".