Exclusive Police cite shrinking budgets and reduced stop and search, as possession offences recorded in England and Wales drop by almost a third

The number of cannabis possession offences in England and Wales has plummeted since 2011 as forces divert shrinking budgets into tackling more serious crime and officers rein in stop and search.

Figures released to the Guardian under the Freedom of Information Act reveal offences recorded by English and Welsh police forces – including penalty notices, cautions, charges and summons – fell by almost a third from a peak of 145,400 in 2011-12 to 101,905 in 2014-15.

Crucially, the figures include all cannabis possession offences, not just those that led to arrests or prosecutions. The fall in offences cannot therefore be explained by police opting for quick cautions over lengthy prosecutions.

What the figures reveal is a silent relaxation of drugs policy in the last five years – and will spark fresh debate about whether there is a case to decriminalise cannabis possession.

Only last week a cross-party group of MPs called for the liberalisation of cannabis laws during a Westminster Hall debate in parliament. The debate was called after a petition to legalise the production, sale and use of cannabis attracted more than 221,000 signatures.

The fall in offences cannot be explained by declining cannabis use. While illicit drug use has fallen markedly since the turn of the century, the most recent Crime Survey for England and Wales showed that the level of cannabis use since 2010 had barely changed. In 2015 6.7% of adults aged 16 to 59 used the drug. In 2010 the figure was 6.5%.

Instead senior police officials pinpointed shrinking budgets, shifting priorities and reduced use of stop and search as the main reasons for the decline. Of the 43 police forces in England and Wales, 42 provided full-year figures from 2009-10 to 2014-15, and 30 provided part-year data from 2009-10 to the latest quarter of 2015-16.

Merseyside police saw the biggest fall in England and Wales. The latest data shows there was nearly a two-thirds fall in offences between April-July 2010-11 and April-July 2015-16.

Supt Mark Harrison, Merseyside police lead for cannabis, said the fall in recorded offences was due to reduced use of stop and search. “Increased scrutiny of police stop-search practices has led to more efficient, effective and targeted stop-searches. Additionally, decreasing police officer numbers will continue to result in fewer stop-searches in the future,” he said.

Significant drops were recorded by England’s large urban police forces and smaller rural ones, and forces in Wales. London’s Metropolitan police, the biggest force in the country, recorded 40% fewer cannabis possession offences in 2014-15 than in 2009-10.

When contacted, however, a Metropolitan police spokesperson said there had been no change in policy towards drugs misuse.

But a spokesperson for Gloucestershire police, which saw a 50% drop in offences since 2010, was clear that money was a factor. “We prioritise different crime areas according to greatest need,” they said, “and our priorities at this time are safeguarding vulnerable people, tackling dwelling burglaries and violence committed with weapons. However, when resources permit, we do investigate cannabis cases and execute search warrants when opportunities present themselves.”

Temporary assistant chief constable Bill Jephson, lead on cannabis for the National Police Chiefs’ Council, said: “The police are having to manage demand with decreasing resources and this requires tough decisions on priorities.

“Cannabis possession has never been treated as a top priority and law enforcement continues to focus their efforts on the basis of threat, harm and risk targeting the serious criminals involved in the supply chain.

“Over the period covered by this Freedom of Information request, police forces have been focusing on making the best use of stop and search. We want to ensure that these powers are only used in the appropriate circumstances. It is likely this will have resulted in fewer offences of simple possession being discovered by police.”

In some regions, the police are openly discussing liberalising drug sanctions. In July, Durham’s police and crime commissioner said he would effectively decriminalise people who grew small amounts of cannabis, a move welcomed by those who argue that Britain’s current drug laws are failing.

Many experts said that “the future must see a debate about the decriminalisation of drugs, certainly of cannabis”. Prof David Nutt, the founder of DrugScience and a former chairman of the government’s advisory committee on the misuse of drugs, welcomed the shift in police thinking but said it was largely down to cost savings.

“The police had been spending half a billion pounds a year giving convictions for cannabis possession. Criminalising young people on this [scale] was a tremendous waste of money.”

Nutt, who has joined a Liberal Democrat “expert panel” to establish how a legal market for cannabis could work in Britain said that it was not clear this government “would look at the evidence and act in terms of policy”.

He pointed out that a Treasury report, leaked last week, showed legalising cannabis could save £200m in court and police costs and raise hundreds of millions of pounds in tax each year. “It would be rational policy to allow access to medical cannabis when 250 million Americans have access,” he said. “But we don’t seem to be able to do even this.”

Kirstie Douse, head of legal services with Release, a drugs advice charity that supports law reform, said a combination of reduced use of stop and search – especially in London – and deprioritisation of cannabis possession by some police forces explained the fall in recorded offences.

“Release welcomes police recognition that possession of cannabis is a low-priority offence, despite the lack of political will to formally acknowledge this. The evidence shows that the use of criminal sanctions to deter drug use is ineffective.”

Mike Penning, the minister for policing, said: “We are clear that all crimes reported to the police should be taken seriously, investigated and, where appropriate, taken through the courts and met with tough sentences.

“Decisions on individual investigations are an operational matter for chief constables based on the evidence available to them and investigations can be reopened at any time should further evidence come to light.

“This government’s drug strategy is working. The proportion of adults aged 16-59 using cannabis in the last year in England and Wales has declined from 9.6% in 2004-05 to 6.7 % [2014-15], with cannabis use among young adults aged 16-24 and young people aged 11-15 following a similar pattern.”