There are only a handful of politicians who are willing call for drugs to be decriminalised, but in private many experts seem to think that this would be a good idea. Chris Mullin took an interest in the subject when he was chairman of the Commons home affairs committee and, in his diaries, he says that David Blunkett, Eliza Manningham-Buller (the then head of MI5) and "a lot of chief constables" were either in favour of legalisation, or at least hinted to him that they might be. Now Mullin can add another name to his list: David Halpern, a former Downing Street policy expert.

Halpern worked for the prime minister's strategy unit from 2001 to 2007, mostly as chief analyst, and he writes about drugs in his new book, The Hidden Wealth of Nations. There was never much chance he was going to get Tony Blair to back the heroin legalisation. But, in the book, Halpern says this approach could cut crime dramatically.





Up to 80% of certain crime types, such as shoplifting and burglary, are thought to be drug related. Visibility of drug-related activity is also known to be an additional driver of fear. A key point to understand is that the best drug strategy depends on the maturity of the drug market in question. When a new drug enters the "market", it can be very effective to criminalise it and police it aggressively. However, once a drug has been around and in use for decades, criminal justice sanctions become much less effective, such as with addicts who have been on heroin for 20 years (or alcohol, in the case of the US prohibition). At this point, a better strategy is to focus efforts on managing the harms. This may involve "legalising", or medicalising, the supply of long-established drugs to chronic users to undermine the criminal suppliers and to stop the person needing to steal or prostitute themselves to pay for the habit. International evidence suggests that such approaches can reduce associated crime by up to 60%.

There are only about two passages about drugs in the Hidden Wealth of Nations, which is scintillating and immensely well-informed and covers almost all aspects of public policy. Halpern is particularly interested in wellbeing and – as his remarks about heroin indicate – he seems to be using the book to flesh out all the policy ideas that he could not get past the prime minister.

Incidentally, Halpern also reveals how he used to select candidates to work in the strategy unit. He would ask them why Britain had a National Health Service, but not a national food service. "What we were after was not just a historical account, but one rooted in the logic of 'market failures' (who would insure those with a high risk of genetic illness); informational asymmetries (you know to eat when you're hungry, but how do you know if you need an expensive medical procedure?); and the nature of public goods (if everybody else gets vaccinated, I don't need to bother – but everyone thinks that)." Anyone who could answer along these lines tended to get a job.