How London Could Effectively Decriminalise Cannabis

London Mayor Sadiq Khan wants to examine the benefits of cannabis decriminalisation. But how much power does he have to change the law?
man smoking joint parliament london
Photo: Paul Davey / Alamy Stock Photo

London Mayor Sadiq Khan has said he will establish a commission to examine the benefits of decriminalising cannabis if he is re-elected on the 6th of May. However, as drug policy experts have pointed out: a commission is one thing, actually acting on the commission’s conclusions is another.

So how exactly could Khan influence the legal status of cannabis?


While the London mayor cannot introduce new laws, if re-elected he could instruct the Metropolitan Police to no longer arrest people for cannabis possession.

“The mayor’s office […] can inform policing policy and could de-facto decriminalise personal drug possession, directing the Met to reduce policing of low-level drug offences,” Niamh Eastwood, director of drug information charity Release, told VICE World News. “This may sound counterintuitive, but after a year of not policing and prosecuting drug possession offences and other low-level offending, Baltimore in the US has experienced a drop in violent crime.”

Five police forces across the UK – including West Midlands and Thames Valley – have already introduced “diversion schemes”, whereby people caught with small amounts of any drug, including crack and heroin, are referred to treatment or given harm reduction advice, rather than being criminalised.

Importantly, though, these moves were led by the forces themselves, not an outside influence. In September of 2020, the Independent Office for Police Conduct told the Met that they should no longer stop and search someone just because an officer smells cannabis in their vicinity, but the justification is still used, prompting scepticism over whether the Met would adopt the diversion scheme model if it was mandated by the mayor. 


Steve Rolles, from Transform Drug Policy Foundation, said any diversion scheme around cannabis possession could encounter resistance.

“Police don’t want to give up the power, as they use it to stop and search for other things,” he said. “A diversion scheme doesn’t get rid of the offence, it just changes the practice, and police presumably retain discretion to arrest and charge.”

However, Rolles said, such a scheme would still be a significant step forward: “Hopefully it’s not just cannabis. It should be for all drugs, because you don’t just decriminalise cannabis. You stop criminalising people for drug use, like the other forces who have implemented diversion schemes.”

While the number of recorded cannabis offences in London has been declining year on year, people are still commonly stopped and searched over suspected weed possession. Almost half of all stop and searches in England and Wales are carried out by the Met, with young Black men in London 19 times more likely to be stopped than the rest of the population. In four out of five stops, nothing is found, and the practice is a source of serious friction between ethnic minority communities and the police.


The government’s Commission on Race and Ethnic Disparities last month advocated for diversion of “low level class B drug possession offences” to address “the disproportionate number of ethnic minority young people going into the criminal justice system”. Policing minister Kit Malthouse has described diversion schemes as “wholly laudable”.

Khan has said it is time for fresh ideas about how to reduce the harms caused by drugs and drug-related crime. “The illegal drugs trade causes huge damage to our society – driving serious and violent crime, damaging people’s health and criminalising too many young people,” he said. “That’s why, if I’m re-elected, I will establish a new London Drugs Commission comprised of independent experts to examine the latest evidence from around the world.” 

Downing Street has called the proposed commission a “waste of time”, saying the government has “absolutely no intention” of changing cannabis laws. This is despite a majority of people in the UK being more likely to support than oppose cannabis legalisation, with only those aged 65 and over narrowly against it, but all other age groups in favour, according to fresh polling released on Tuesday by YouGov. In London particularly, there is strong support for full cannabis legalisation.

The Liberal Democrat candidate for London mayor, Siobhan Benita, has called for cannabis legalisation, while Green candidate Sian Berry has urged for an end to weed searches. Tory candidate Shaun Bailey has called for a law and order approach, going as far to suggest that large companies should carry out random drug tests on staff.

The Met said it was not able to comment on claims or pledges made during election campaigns.