Danny Kruger is Chairman of Only Connect, a criminal justice charity.

This week, Elizabeth Truss announced the application of an old technique to a new problem. Telling the Commons of efforts to reduce drugs being flown into prison, she explained: “We now have patrol dogs who are barking, which helps deter drones”. The Government’s policy on drugs in prison is not quite as barking as this – but nearly. Last month, the Justice Secretary published a White Paper on prison reform which, she said, promised “the biggest overhaul of prisons in a generation.”

But it said nothing of any substance on the most pressing issue facing the prison system. Without reducing the impact of illegal drugs – and, in particular, the constant stream of newly invented and wildly unpredictable psychoactive substances – prisons will continue their descent into violence and squalor.

To be fair to the Justice Secretary, measures to combat drugs were announced in the White Paper, but these were merely an extension of current policy. On the supply side – the introduction of drugs into prisons – we will see a combination of high-tech and old school: sophisticated phone jamming technology to disrupt the drugs business, plus more sniffer dogs. As well as the dogs, grates on windows will stop the influx (probably greatly exaggerated) of drugs delivered to cell windows by flying drones.  And families visiting prisoners will be subject to more surveillance and searches.

You will notice this approach doesn’t affect the largest group of people who enter and leave the prison each day: the staff. This week, BuzzFeed published its investigation into English prisons, which found strong evidence of both large-scale corruption in jails and of a pattern of concealment by the authorities. Multiple sources confirm that the majority of drugs and mobile phones are smuggled in by staff. In HMP Pentonville – where a prisoner was recently stabbed to death and another two escaped with the help of a large drill – an officer allegedly supplied a prisoner with a gun.

Although reports like these are rife, action is rarely taken. After one internal investigation at Pentonville – leaked to BuzzFeed – which produced serious charges against 31 officers, all but three cases were thrown out by the governor; the three officers were sacked, but later cleared and reinstated. This is what happens when political fear of bad headlines combines with an overmighty trade union.

So much for the supply of drugs. On the demand side, the system only has one thought in its head: mandatory drug testing of all prisoners. This common sense idea is, in fact, a bad idea, for three reasons. First, because it tells us nothing other than the fact some prisoners use drugs, which we knew already. Second, because we don’t do anything about it: prisoners who test positive suffer few if any penalties (and anyway all the research shows that drugs users – in prison or out – are highly resistant to the supposed deterrent effect of penalties). Third – and worst of all – testing doesn’t work on its own terms of giving an accurate picture of drug use in prison. Only seven per cent of tests show up positive, when we know that well over half of prisoners are regular users.

The real effect of mandatory testing is to fuel the search for drugs which beat the test: the so-called “legal highs”, most notably the ‘synthetic cannabinoid receptor antagonists’ (SCRAs), chemicals sprayed onto dried plants and smoked in an odourless, highly toxic, spliff. Trading under names like Spice and Mamba, SCRAs are cheaper, easier to get and more popular than the banned stuff. According to research from the prison charity User Voice, 33 per cent of prisoners smoke Spice. They call it ‘bird killer’ – bird being slang for prison time – because it puts you into a pleasant dream in which your cell, its boredoms and horrors, seem infinitely remote: as one prisoner put it, ‘you take a puff, and eight hours later you wake up.’

Spice is impossible to police because, when the authorities develop a test for it, or include it in the list of banned substance, its makers simply tweak the formula and lo! a new drug is born. Prison drugs policy is like an addict, always chasing a higher high, for diminishing returns. The result is the abuse and exploitation common to addicts. Drug debts are the primary cause of prison violence. Bullying is endemic – including, according to the latest report from the HM Inspectorate of Prisons, the use of mentally ill prisoners as ‘spice pigs’ to test new drugs before they are released to the market. Meanwhil,e the efforts to disrupt the drugs business simply inhibit the positive, purposeful activity prisoners should be engaging in.

We have created the perfect conditions for a distorted seller’s market: barriers to entry which mean only the powerful can muscle through, no regulation of their activities once they’re in, and no competition in the form of alternative positive activities.

As the previous Chief Inspector Of Prisons, Nick Hardwick, has put it, the main problems afflicting prisons are “lack of imagination and failure of empathy” by policymakers. The key imaginative and empathic leap is to recognise that the “drugs problem” isn’t a problem about drugs. It’s a problem about isolation; a consequence of the lack of positive relationships in the user’s life, and the lack of useful, fulfilling work to do. As one prisoner puts it “banged up 23 hours a day in a large toilet with someone you have never met before – who wouldn’t want a mind-altering substance?”

A report this week from Volteface, a drugs think tank and pressure group, makes a number of sensible and practical proposals for tackling the problem of drugs in prison, including an end to pointless mandatory testing and a concentration of resources on intelligence-led disruption of the supply of drugs instead of blind, blanket approaches that don’t work. But their main proposal has nothing to do with drugs.

We won’t reduce drug use until prisoners have something better to do with their time than smoke themselves into another world. In the absence of significant new funding for prisons – vanishingly unlikely – this means only one thing: sending less people to prison, to free up the system and make prisons purposeful, busy places. Instead of more dogs and less drones, the driving objective of the Justice Secretary should sentencing reform to reduce prison numbers.