Sadiq Khan is considering a surprising initiative to stop the killings on our streets – a pilot scheme that would decriminalise cannabis in three London boroughs. Under-25s caught with the drug would no longer be prosecuted. These young people would be offered speeding course-style classes or counselling instead.

Since he became mayor, Mr Khan has overseen an explosion of gang-related violence. Indeed, 2021 was the worst year for teenage killings in London on record. You might reasonably ask how decriminalising a major driver of youth violence can possibly be the answer to the bloodshed. But the war on drugs has been conspicuous for its failure. A new approach is definitely needed.

When I first read about Mr Khan’s initiative, I was sceptical. Those in authority tend to treat cannabis as if it were still the relatively harmless, naturally grown product of 30 years ago. But now, it is the sweet, sickly smell of skunk that is all-pervasive on our streets. Skunk, as I have seen first-hand when I befriended a south London gang, is a dangerous drug that wrecks young lives and leads to violence and death. This is the drug that Mr Khan wants to decriminalise.

Skunk is grown artificially and packed with chemicals to increase its potency. “You don’t know what’s in it,” complained one long-term user. “Broken glass and they even p— in it.” At the high end, skunk paid for with Bitcoin is delivered from America, rainbow hued and in glossy, brightly coloured vacuum packs with names like Serial Milk, Cookies and Gelato. It costs three times the price and is powerful and highly addictive.

All skunk, however, contains THC – the substance that gives the stoned feeling but also causes side effects like paranoia and hallucinations. According to the Royal College of Psychiatrists, people who use cannabis, particularly in their early teens, have a higher than average risk of developing a psychotic illness, including schizophrenia or bipolar disorder. All the young men I interviewed, whether white working class or African Caribbean, had started using skunk at age 11 or 12. A man who works in a pupil referral unit says his pupils smoke two or three spliffs even before they arrive at school. “They think they are functioning but they are just shutting down their brains.”

Against the powerful seduction of these drugs, what hope is there for Mr Khan’s belief in the efficacy of counselling? More than many might think. The young drug users I befriended had no idea of those dangers until I pointed them out. It proved a revelation. They all had friends who had been sectioned, some at a very young age. “Gonna visit my mate in the Maudsley,” (the psychiatric hospital in south London) was a regular activity. But they had never linked that to drug-taking. One former drug dealer said the authorities have to “get real” about the cannabis awareness classes. “They need to take the youths into mental institutions and see my people banged up there. Serious man.”

But can education really help stop the violence on our streets? Here Mr Khan has a surprising ally. A former heroin dealer explained he had little concept of “the realness” caused by his business. “I was at the top of the game. I didn’t see the outcome at street level.” Then he was pulled in by a police officer who took the time to tell him “some true stories of what I was contributing to – the neglect of children, the care system, heroin babies. It didn’t change me straight away but it got me thinking.” He believes any sort of education given to young dealers must “spark a thought process”.

The stakes are very high. One young man described a recent incident as an example of how dealing fuels violence. A 15-year-old bought a bag of cannabis for £10. “But it was rubbish weed”. So he complained to his friend. But his friendship group is a small circle. “Soon the first man is demanding ‘Why are you dissing my weed?’” They met up, “some confrontational ting ending up with one stabbing the other to death – he lost his life over a gram of weed.”

The Government is also alarmed that Khan’s move will set him on a collision course with its call for tougher action on the people who buy drugs. Yes, confiscating the passport of a middle-class coke user might have a certain impact. But between 2016 to 2020, nine in 10 drug proceedings brought against young people in Lewisham were for cannabis possession. Maybe it is time to try something new.