Scotland’s drug mortality rate cannot be shelved as just another misery statistic. It has risen by 27% in a year and is three times England and Wales’s rate, 50 times Portugal’s and higher even than that of the United States. Westminster is clearly deaf to this tragedy. There is only one solution. Declare it Scotland’s problem. Let Scotland decide what to do.

Every country in the developed world is now inquiring, experimenting, searching for how to tame the menace that modern narcotics pose. Every country, that is, except Britain, where for half a century a futile “war on drugs” has been delegated to the police, the courts and the NHS. The sole beneficiaries have been drug dealers and their political sponsor, Her Majesty’s Home Office, relieved of lifting a finger in response.

It is their policies that underpin the street sales and powder factories of a multibillion-pound underground industry

There is now little point in preaching the gospel of legalisation. Countless seminars, conferences and inquiries have tried to work out how best to tackle Britain’s booming drugs industry, legitimate and illicit. They never address the root of the trouble, the minds closed to the subject in Westminster and Whitehall. We can scream “look to the Netherlands, Portugal, Canada, California”, and MPs and officials clamp their hands to their ears.

These people and not the addicts or dealers are Britain’s drugs problem. It is their policies, dating from the antiquated 1971 Misuse of Drugs Act, that underpin the street corner sales, powder factories, shooting galleries and lightly dusted lavatory seats of what the act has turned into a multibillion-pound underground industry. It is an industry Whitehall refuses to regulate, let alone tax. Public servants who, in their home life, may be open to reason, at work become architects of cruelty, well-illustrated in the cynical handling of last year’s medical cannabis scandal, which is still unresolved. As in so many of areas of its responsibility, the Home Office displays the open-mindedness of a Spanish Inquisition.

Reform must search for weaknesses in the wall of reaction. Chief weakness is the frontline, where criminalisation is collapsing through sheer unenforcibility. Led by Durham, one force after another is refusing to arrest its way out of the drugs problem. London’s commissioner, Cressida Dick, says she would need “an army of 100,000 officers” to seek out and charge all the capital’s drug users. Anarchy may yet prove the most effective agent of change. But even an attempted shift from imprisonment to care and rehabilitation suffers from the steady closure of treatment centres under local authorities’ austerity. Like ever rising drug abuse in prisons, it is as if British government was seeking to aid an industry with which it claims to be at war.

Liberal Britain relieves its anti-Brexit fury by labelling Donald Trump’s US antediluvian. Yet even Trump is not enforcing federal bans on states that experiment with cannabis law reform. Thirty-three states have legalised medicinal or recreational use, as has Canada. An industry worth many billions of dollars is going legitimate, as did alcohol with the end of prohibition.

Visitors arriving at Los Angeles airport are greeted with an advertisement for California’s chief marijuana retailer, MedMen. It reads: “Welcome to the new normal.” Half of Oakland’s cannabis licences now go to formerly imprisoned dealers. Colorado, a state the same size as Scotland, reports revenue from its cannabis tax passing $1bn in five years of operation. Could Scotland not use such money? The American experience is not all roses. It has a huge “hard” drug abuse problem, partly due to the introduction of new opioids and other substances.

But slowly drugs are coming to be seen as a social, not a law-and-order issue, with control and legal regulation the sensible response. At least marijuana is being removed from the drugs cocktail. Research shows no rise in cannabis usage with legalisation, while California shows an 8% fall among teenage users.

Britain is light years adrift of such reform. The one hope might be Scotland. It already enjoys a degree of devolved power over crime and punishment. This spring it publicised its remarkable success in combating knife killings. It had halved the rate in 10 years, largely thanks to violence reduction schemes copied from Los Angeles and Boston. Likewise, a campaign against alcohol-related deaths exploited delegated powers to levy local taxes. A rise in minimum retail prices has driven Scottish alcohol consumption to an all-time low. Both these initiatives were classic examples of local discretion leading to reform, where central government policy was stuck in a political rut. Yet, ever since devolution, the Home Office has refused to allow Scotland power to vary the 1971 drugs act. With its antique schedules and ineffective punishments, this act echoes the days of stocks, thumbscrews and treadmills. To the Home Office it is holy writ.

Scotland has a desperate problem. Scenes of addicts on its streets will hardly attract investors, employers or tourists. Yet it has a mature administration with a proven readiness to search the world for solutions to its woes. Its police chiefs, law officers, academics and newspapers are pleading to be allowed to tackle the drugs crisis for themselves. Cannabis legalisation may be part of a solution. Prescription heroin and cocaine may be another. That should be for Scotland to decide.

Parliament can keep to its medieval taboos. It can sail blithely on through its dark night of reaction. But it has failed utterly to win the war on drugs in Scotland. The least it can do is set Scotland free.

• Simon Jenkins is a Guardian columnist