They sneaked it out in December.

The Home Office report is called 'Drug Strategy 2010 Evaluation Framework – evaluating costs and benefits'. It is not the sort of title which seduces the attention, but inside you can find a fascinating, topsy-turvy, down-the-looking-glass world of hopeless causes.

The purpose of the document is to set out the kind of evidence you'd need if you wanted to work out whether the government was getting value for money with its anti-drugs programme.

On its own, that's a creditable aim. The more we look into the spending on anti-drug programmes the more we highlight the chasm of financial and human waste which constitutes prohibition.

What we get, of course, is nothing of the sort. Instead, lodged innocuously in the middle of the report and couched in impenetrable language, there is a startling admission.

It reads:

There are challenges in other areas, however, particularly around developing a suitable counterfactual, or measuring impact on actual behaviour. For example, establishing the conditions for a robust counterfactual for enforcement is difficult and as a result, little robust evidence of impact is available either nationally or internationally.

What this adds up to is that the Home Office has no idea whether it has achieved anything with its enforcement programme against drugs. That's a remarkable thing to say given independent estimates suggest it spends up to £3.655 billion a year on enforcement alone. The figure rises sharply when you include initiatives such as early intervention or treatment.

Imagine any other area of life – in public service or the free market - where you were spending billions a year and were unable to show any evidence of achieving your objective.

Even when it comes to areas such as early intervention ("a lack of evidence of long-term outcomes") or information services like FRANK ("little is known about how this translates into behaviour change") the Home Office has no idea what, if anything, it is achieving.

The hypocrisy is astonishing.

For 'education and information approaches', the document says:

These interventions centre on the logic that if rational individuals are aware of the dangers associated with drugs, they will choose not to take them.

That must ring hollow with former Advisory Council on the Misuse of Drugs boss David Nutt, who was sacked from his position when he dared to speak the statistical reality about the minimal dangers of ecstasy use.

But the Home Office pleas about the difficulty of collecting accurate data ring particularly hollow given that they have previously tried to cover up evidence about how useless their policy is.

When Transform tried to gets its hands on the Home Office's value for money study in 2010, officials discussed keeping it out the public eye because it would help those campaigning to end prohibition.

Luckily - and with the Home Office's usual capacity for incompetence – they accidentally sent the internal memo to BBC’s Martin Rosenbaum. It read:

The release of the report entails the risk of Transform, or other supporters of legalisation, using information from the report to criticise the government's drug policy, or to support their call for the legalisation of drugs and the introduction of a regulated system of supply. These risks should be considered in reaching a decision on whether to release the report, as recommended.

It was a particularly disgraceful affair, given it went against guidelines saying that FoI requests should be dealt with 'blind' – not considering who was requesting the information. Instead, civil servants were making FoI decisions on the basis of how damaging they thought the information would be to ministers.

If the Home Office really cared about establishing the financial costs of the war on drugs, they would have paid rather more attention to the home affairs committee's request that a royal commission be set up which could evaluate the wealth of evidence flowing in from experiments overseas.

We are in a prime position to see how various systems of drug reform work, with Portugal replacing criminal penalties for a new emphasis on treatment, the legalisation of cannabis in Washington and Colorado, and the introduction of a state monopoly cannabis production system in Uruguay.

Lib Dem Home Office minister Norman Baker is visiting some of these areas, but the opportunity for full-scale monitoring of the experiments being conducted around the world has been ignored.

There's plenty of pre-existing international evidence as well, from governments who still think it sensible to sometimes base their actions on evidence rather than mania.

The Czech Republic removed punishment for possession of small amounts of illegal drugs towards the start of the post-Communist era. In 1999, it reintroduced criminal penalties for certain amounts of drugs, but the controversy around the law meant the government actually studied the impact of the measures.

Why isn't the Home Office interested in it? Probably because it found that criminal penalties did not decrease the availability of illegal drugs, or the number of current users, or the number of new users. There was no improvement in 'negative health consequences' or 'social costs' and the policy was economically loss-making.

With a level of progressive insight evidently beyond the abilities of the Home Office, the Czech government consequently decriminalised possession again.

Of course, Portugal, Uruguay and the Czech Republic are not the same as Britain, but that does not mean we can't learn from them, rather than closing our ears to experiences overseas.

The Home Office won't look at these historic examples or assess the current ones because its attitude to drugs is based not on evidence but on quasi-religious anti-drugs fervour and total capitulation to the Daily Mail.

Instead, it will publish more despairing evaluation reports, into which it will sneak in the indisputable truth: They're pouring money down the drain and they've got nothing to show for it.

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