Stephen Pollard argues that this piece by Antonio Maria Costa, formerly Executive Director at the United Nations Office on Drugs and Crime, "simply rips apart the dangerously sloppy thinking from those who argue for the legalisation of hard (and soft) drugs." Well, that's one way of looking at it.
Alternatively, one can think it profoundly misleading and alarmist. Costa argues that any attempts to introduce sanity (that's not how he describes it) to the drug conversation will inevitably produce a sharp rise in drug use, and consequently addiction. Leaving aside the philosophical debates about drug-use, this is an argument that while intuitively plausible isn't necessarily endorsed by the evidence available.
As it so often the case these days, Portugal is the poster-country for reform. True, Portugal didn't legalise the drug trade but decriminalising drugs - both hard and soft - has not led to an increase in drug consumption. Indeed, nine years on there is no demand for returning to the old, failed policies of the past.
Perhaps what works in Portugal would not work in Britain. (Cultural factors could suggest this could be the case.) And perhaps Portuguese policies can't be exported worldwide. But the fact that drugs are much more popular in Britain than they are in Portugal suggests that prohibition doesn't necessarily work while decriminalisation doesn't necessarily produce a nation, or even a generation, of drug addicts.
So there are degrees of prohibition and degrees of liberalisation. Portugal's history - and that of the Netherlands which also enjoys lower rates of drug-use than either the UK or the USA - suggests that Costa's claim that "in the absence of controls, it is not fanciful to imagine drug addiction, and related deaths, as high as those of tobacco and alcohol" is at least questionable and more probably typical of the overblown scaremongering favoured by Drug Warriors.
In any case, his suggestion that 30% of the population (worldwide!) could become drug addicts were prohibition repealed seems unduly alarmist. By his own figures it would need a 50-fold increase in the number of daily drug users. This too seems unlikely. Similarly, the idea that drug-related deaths could run at comparable rates to smoking-related deaths is, um, improbable. If it were true you might expect roughly 40% of existing drug users to die from drug-related complications.
This does not happen. Indeed, the vast majority of drug users - both habitual and casual - are able to lead perfectly ordinary, normal lives. (It's also the case that many people grow out of drug use.) It is not obvious that a different legal framework would change this. (Equally, a more open, liberal policy might find it easier to deal with the unhappy consequences of addiction.)
Drugs are not dangerous because they are illegal: they are illegal because they are dangerous to health. Unfortunately, ideology has displaced health from the mainstream of the drug debate and this has happened on both sides of the prohibition versus legalisation dispute.
Costa argues that a worldwide programme of legalisation would wreak havoc on the developing world, enslaving entire populations to the pernicious thrills and horrors of drug abuse. This could happen, but since there's no prospect of a worldwide end to prohibition and so on it's hardly the most immediate or pressing issue. Instead it's notable that some of the latin American countries most intimately involved with narcotics are among those rethinking policy.
Legalisation or even decriminalisation may not solve all problems associated with drug use. But few people, I think, claim it would. Nevertheless, it is hard to see how in the long and even medium term liberalisation could produce unhappier results than current policy. That may be a modest claim but it's not a minor one.
UPDATE: Ewan Hoyle has more.