We can predict with some precision what will happen when the government criminalises the possession of nitrous oxide. Hundreds of thousands of young people will still inhale this laughing gas from balloons. Criminal gangs will take charge of meeting the demand, handing them a new and lucrative revenue stream. Our ability to regulate the substance will cease, posing greater risks. Those who need medical care will be deterred from seeking it, fearing being pursued by the police. A minority of users will be arbitrarily criminalised – in the words of the Law Enforcement Action Partnership, which represents former police officers, for “possessing substances which have a lower harm rate than ‘legal’ highs such as alcohol”. Because of an institutionally racist criminal justice system, those targeted will be disproportionately Black, their future job prospects damaged for enjoying a quick high from a balloon. You do not need to be in possession of a time machine to know any of this. This is where prohibition of mind-altering substances always leads. The most notorious example, of course, was the US prohibition of alcohol in the 1920s, which led to a quadrupling of deaths from “poisoned liquor”, while handing criminal gangs a monopoly over supply of a hugely profitable industry: robbery, theft and homicide soared as a consequence. Since US president Richard Nixon launched the “war on drugs” in 1971, more than $1tn has been wasted on this calamitous failure. Globally, the number of adults using drugs at least once a year jumped by nearly a third in the first half of the 2010s, while drug deaths soared by a staggering 145%. Banning drugs does not make them go away: it just means more harmful forms circulate, people with problematic relationships don’t get help and criminal gangs are handed a profitable trade. But prohibition is always in defiance of the evidence. The government referred nitrous oxide to its Advisory Council on the Misuse of Drugs (ACMD), which apparently exists solely to be ignored by politicians. Its review was clear: nitrous oxide should remain under the Psychoactive Substances Act, which prevents it from being sold for recreational purposes, but the health and social harms did not justify criminalising possession. Indeed, the review noted that use has been falling anyway: while use among 16- to 24-year-olds peaked at 9% in 2016-17, it has since fallen to 3.9%. This reflects a wider trend: Briton’s youngsters are a sober generation, increasingly turning away from alcohol and illegal substances alike. We’re told laughing gas drives antisocial behaviour among users, but according to the ACMD, “there is little evidence to suggest that the vast majority are likely to become aggressive or violent”. As for health risks, the number of users requiring treatment is “very low”. Alcohol is a far more harmful drug – both in damaging users’ health and driving aggressive behaviour: it is a factor in four out of 10 violent crimes in England alone. Yet here we are, proposing criminalising young Britons for possession of a substance that poses a far smaller risk to themselves or their fellow citizens. Indeed, much of the moral panic over nitrous oxide revolves around litter: and indeed, gas canisters in public spaces can be an unsightly mess. Fine: but littering is already illegal. We are not proposing banning the possession of Coca-Cola bottles, plastic bags, takeaway packaging or other commonly littered objects, after all. The recycling deposit scheme proposed by drug campaigners is a far more rational solution. At the root of this policy is the fear, contempt and hatred towards younger people which much of our society nurtures. This morning, the Tory minister Chris Philp justified prohibition of laughing gas because of “antisocial behaviour”, offering as an example “people, young people in particular, loitering in public places like parks”. Heaven forbid anyone should “loiter” in a park. Here is a policy that drips with classist and racist hypocrisy. What of the politicians who support criminalising – and often ruining the lives – of the disproportionately young working-class Black people targeted by the police? Like Michael Gove, allowed to pontificate on TV about the horrors of laughing gas despite having admitted to taking cocaine in his 30s? What of Keir Starmer, who refused 14 times to answer when asked by Piers Morgan whether he’d taken drugs, and joked he’d had “a good time” when asked the same question by schoolchildren, who backs this absurd crackdown? What of the traces of suspected cocaine found after parties at Liz Truss’s grace and favour house, or the cocaine coating the bathrooms of the House of Commons? Our politicians should be honest: they have the right to get high without fear of prosecution or their careers being ruined, while others – often poor, often Black – suffer brutal consequences. A rational society would follow the example of Portugal, where drug use has been decriminalised. That doesn’t mean a free-for-all: it means those with problematic relationships with drugs get the support they need, rather than being treated as criminals. Yet what hope when the two biggest parties stick their fingers up at the experts: the last Labour government fired Prof David Nutt, its chief drug adviser, when he correctly argued that ecstasy and LSD were less dangerous than alcohol. A third of all drug-related deaths in Europe happen in the UK: this is a health crisis that the criminal justice system has failed to solve. How depressing that while several states in the US – the country that pioneered the calamitous failure of the “war on drugs” – are embracing decriminalisation, the consensus here thumbs its nose at science and reason. Lives will be ruined, not by laughing gas – a relatively harmless indulgence – but by this self-defeating prohibition that has never worked, and never will. Owen Jones is a Guardian columnist