The really important question about David Cameron and drugs has not been asked. The pressing issue is not whether the Conservative party wunderkind-on-a-roll and potential leader ever took drugs (unless he has done so in recent years, at which point it ceases to be a youthful indiscretion and becomes a disqualification from office) but what his views are about how to tackle drug abuse. And here he is on entirely the wrong side. It is not just that he is equivocal about cannabis, indicating that he disagrees with his party’s policy of re-classifying it back to the more serious class B category of prohibited dugs (although he has also implied that he is rethinking that, in part at least because of the strength of skunk). It is that – despite careful caveats, so that he does not openly come out and say he wants to legalise drugs — he lines up with the drug legalisation lobby, and has displayed that lobby’s utter inability to understand the importance of law in signalling social disapproval and regulating behaviour.

On May 23 2002, he wrote in the Guardian that the war on drugs could never be won. Pointing out that drug policy had been an abject failure, he observed that this was because the focus had been on law enforcement:

Customs and Excise is supposed to keep the drugs out. The police and the courts are supposed to catch and punish users and dealers. It hasn't worked. There have never been more drugs on our streets - and the prices have never been lower. It's time for a new approach.

Wrong. The problem is not law enforcement. It is that the law not been enforced. Customs and Excise took a disastrous decision to stop actively targeting cannabis; as a result, cannabis flooded the British market, the price fell to rock bottom, cannabis use shot up and dealers moved increasingly into hard drugs to keep up their profit margins. On top of that, the police have for years failed to enforce the law against users, preferring instead to concentrate on catching dealers. This is a disastrous strategic error. The drug trade is driven by demand, not supply. And on top of all that has come this government’s catastrophic mixed messages about drugs, reclassifying cannabis to give the impression that a) it is not that dangerous (wildly untrue) and b) that it is no longer illegal (also untrue). The only successful drugs policy is one of zero tolerance, which involves the triple approach of law enforcement, treatment and prevention, as practised for example in Sweden where despite recent ups and downs the success rate in getting on top of drug abuse dwarfs anything that we have done.

What the Swedes understand is that drug policy only works if all the signals that a society sends out consistently say that drug abuse is an evil which simply will not be tolerated. That does not mean banging up every user. It does mean that drug use — quite apart from its supply — will not be tolerated and so there will be strategies for preventing it from happening and for dealing with it in a variety of ways when it does happen. If blind eyes are turned to some drug use, such as cannabis, on the (utterly mistaken) assumption that it is relatively unharmful, this destroys the consistency that is the absolute requirement to hold a moral and behavioural line.

Instead, Cameron comes up with the classic ‘harm reduction’ approach which, whether its adherents admit it or not, is a figleaf for legalisation. No doubt he is genuine when he says he abhors drug use and wants more effective strategies to combat it. But like so many people, he seems to have fallen for the callow and cynical sophistries which have allowed the deeply disingenuous and dangerous doctrine of ‘harm reduction’ to take root. Instead of aiming to prevent drug use, this approach merely seeks to minimise the harm it does. And to achieve that, it is necessary for drug use to be legalised so that it can be ‘managed’. So Cameron comes up with all the usual ‘harm reduction’ arguments – targeting help at users rather than seeking to prevent them from becoming users in the first place, providing injection rooms to ‘clean up the streets’ and prescribing methadone and even heroin to users to get them ‘to get off the streets and start to rebuild their lives’. True, he also says: ‘Ultimately, all treatments should have abstinence as their goal’; but treating with methadone and heroin usually means merely maintaining addicts in a state of addiction. This is not so much harm reduction as a surrender to harm creation.

In a diary for the Guardian Unlimited website in 2001, he wrote:

I am an instinctive libertarian who abhors state prohibitions and tends to be sceptical of most government action, whether targeted against drug use or anything else...Hounding hundreds of thousands - indeed millions - of young people with harsh criminal penalties is no longer practicable or desirable.

This is a very instructive statement. What he is effectively saying here is that he is instinctively sceptical of the value of law as the principal signaller of social opprobrium and policer of social order. It is therefore no surprise that he has also said that he believes that the UN should consider legalising drugs. If this were to happen, millions of mainly young people would be sucked into drug use, with incalculable ill-effects on both themselves and the societies in which they live.

The UN conventions have at their core the aim of eradicating drug use. There is currently a covert and increasingly successful global campaign under way to undermine and eventually destroy those conventions so that drug use can be permitted instead. This truly evil campaign, which would if successful result in misery for millions and most particularly among those who are most vulnerable to both the blandishments and the catastrophic damage of drug use – ie, those at the bottom of the social heap – is now firmly entrenched within the highest counsels of the British establishment and making more headway all the time. It is a campaign representing the nadir of social nihilism and irresponsibility.

If conservatism means anything at all, it is surely to defend society against such catastrophic predation. If the Conservative party votes to have as its leader someone who shares such attitudes, it will be signalling in the most unequivocal terms that it has no understanding of what is needed to defend or restore social order, and therefore has become utterly unsuitable to govern this country.