Government figures sent to Norman Lamb MP reveal fall of 19% since 2015 in people prosecuted for possession

Police forces are in effect decriminalising cannabis, campaigners say, after uncovering figures that show a substantial fall in the number of prosecutions and cautions for possessing the drug.

Last year only 15,120 people in England and Wales were prosecuted for possession of cannabis, a fall of 19% since 2015. Police issued cautions to 6,524 people in 2017 – 34% fewer than two years before.

The figures from the Ministry of Justice were released in response to a parliamentary question from the Lib Dem MP Norman Lamb, who called for a “regulated cannabis market” to protect public health. “It would confound all expectations if the number of people actually in possession of cannabis is falling, which strongly suggests that police are starting to decriminalise regardless of the government’s stubborn refusal to legalise and regulate the sale of this drug,” he said.

The debate on cannabis has reopened since the case of Billy Caldwell, the severely epileptic boy whose mother has been fighting to be allowed to treat his condition at their home in Northern Ireland using cannabis oil.

Although the home secretary, Sajid Javid, has announced a review of cannabis for medical use, Downing Street has said the government has no intention of decriminalising the drug. Yet there have been a growing number of calls from senior politicians and police chiefs for Britain to join Canada and US states including California, Massachusetts and Colorado, where cannabis is available for recreational as well as medicinal use.

Jeremy Corbyn, the Labour leader, said this month that “criminalising people” was not a good idea, while William Hague, the former Conservative foreign secretary, has said Britain ought to be preparing a lawful, regulated market in cannabis for recreational use.

The ministry’s figures show that nearly every police force gave fewer cautions and pursued fewer prosecutions for cannabis possession. Only in Cheshire was there a small rise in prosecutions, of 3%.

Facebook Twitter Pinterest Norman Lamb MP. Photograph: Linda Nylind/The Guardian

“The fall in prosecutions and cautions for cannabis possession is a welcome trend and a victory for common sense,” Lamb said. “The ‘war on cannabis’ unfairly stigmatises and criminalises young people who are doing no harm to others, while tying up police resources which should be better used tackling harmful crimes.

“However, this issue should not be left to individual police forces. We cannot tolerate a postcode lottery where cannabis users may or may not be prosecuted depending on where they live. The government must bring forward proposals for a regulated cannabis market in the interests of public health, with strict controls on price and potency, and give parliament a free vote.”

The Lib Dems have campaigned for legalisation since 2017, while the Green party, the SNP and Plaid Cymru favour decriminalisation.

Around 2.8 million people aged 16 to 59 took a drug last year, according to the Crime Survey of England and Wales, and more than one-third of adults have taken illegal drugs at some point.

The total number of arrests made for drug possession was 108,098 for the year ending June 2017, according to the latest available figures for police recorded crime, which is 36% down on 2006-07 and 10% less than the previous year.

Instead of offering a caution or prosecuting offenders, police have other options to sanction those in possession of drugs. They can give an official “cannabis warning”, which places a record of the incident on the police national computer, and a penalty notice for disorder, which is similar to a parking ticket.

But uses of both have fallen dramatically over the past decade. Police issued 139,666 notices in 2007, but only 18,211 last year. Similarly, the number of cannabis and khat warnings has dropped from 107,241 at their peak in 2009 to 33,514 in 2017.