The Crown Prosecution Service has faced a barrage of criticism after rape convictions in England and Wales fell to a record low, with police publicly censuring its charging policies and a judge paving the way for a landmark legal challenge.

New figures revealed that prosecutions and convictions more than halved in three years even though reported rapes increased. Despite police recording more than 55,000 rapes in 2019-20, there were just 2,102 prosecutions and 1,439 convictions. Three years earlier, just over 41,600 rapes were recorded and there were more than 5,000 prosecutions and nearly 3,000 convictions.

Concerns have been raised that the CPS is refusing to take cases to trial out of concern that jurors will be swayed by myths and misconceptions about what a rape victim should look and sound like, especially when alcohol or mental health problems are involved. In 90% of rapes, the parties are known to one another, but acquaintance rapes can be difficult to prosecute.

Despite concern that “digital strip searches” – where police can request years of phone records from complainants in the process of investigating a rape – were putting off victims, they were only scrapped this month.

Fewer rape cases were referred by police to the CPS last year – down 40% in three years – but the director of public prosecutions, Max Hill, denied the CPS was sending a message to officers not to send them challenging cases.

Senior police figures appeared to contradict this message on Thursday, in a rare public criticism of CPS charging policy.

In a joint statement, the National Police Chiefs’ Council’s leads for rape, domestic abuse and charging said the fall in convictions was “very concerning”, adding: “[W]e are hearing from our officers that it is becoming harder to achieve the standard of evidence required to charge a suspect and get a case into court. Victims tell us clearly how important it is to them to have the evidence tested in this way.”

Sarah Crew, the most senior police officer for rape in England and Wales, told the Guardian she was personally “bitterly disappointed” in the further drop and there was concern among police that there had been a change in the level of evidence needed to bring a charge.

She said officers were trying “really hard” to work with prosecutors to reach the required standard, but were finding that the amount of information required had increased and the process was taking longer. “The second point that they tell me is that they think that the interpretation of what is required, the evidential test, has changed.”

She said this might be due to a breakdown in communication between the police and the CPS, but that she was concerned that the test may not be being applied correctly. If that was the case, she said, it needed to be rectified by the two services working together.

“You join the police service to keep people safe and get justice for victims, and every single one of us wants to achieve that, but there’s an awful lot to do,” Crew added.

Meanwhile, a high court decision not to examine whether the CPS has changed its prosecution policy and practice has been overturned by the court of appeal. The Centre for Women’s Justice, on behalf of the End Violence Against Women (EVAW) coalition, argues that the CPS has become more “risk-averse”.

Two years ago, the Guardian revealed that prosecutors in England and Wales had been advised in training seminars to put a “touch on the tiller” and take a proportion of “weak cases out of the system”, because such a move would result in fewer prosecutions but a higher conviction rate. The conviction rate in 2016-17 was 57.6%, almost the lowest on record. Thursday’s figures also show the highest conviction rate on record, at 68.5%.

The CPS has consistently denied any change in approach.

The Centre for Women’s Justice director, Harriet Wistrich, said the decision to grant a judicial review of CPS rape charging policy and practice in the court of appeal was historic.

“They have accepted it is arguable that the CPS did change their policy, failed to consult, and their actions ultimately led to a fall in rape prosecutions, which discriminates against women, who are the majority of victims. This may amount to systemic illegality,” she said.

A CPS spokesperson said EVAW had originally argued that the CPS had adopted a “bookmaker’s approach” but that that had been ruled unarguably and demonstrably wrong, and EVAW had not appealed against that finding. “However, the court of appeal has today decided that other procedural aspects of their claim should be the subject of a full hearing, which will be in argued in due course.”

The news came on the same day that the CPS announced a five-year blueprint to tackle the “justice gap” between the number of reported rape cases and those that make it to court, promising improved working between prosecutors and police, “fully resourcing” specialist units, and a consultation on pre-trial therapy guidance and training for prosecutors on victim and offender behaviour.

The announcement, however, was overshadowed by its own data, which showed that it prosecuted and convicted fewer people for rape in the year to March 2020 than in any other year for which data exists.

A CPS spokesperson said: “We have been working hard to reverse the trend we’ve seen in recent years. It is early days, but there are encouraging signs, with a steady increase in both the proportion and number of cases charged. If our legal test is met, we always seek to prosecute.”

While the number of charges brought by the CPS increased slightly, by 6% to 1,867, at the current rate of improvement it would take almost 20 years to return to the charging rates seen in 2015-16.

The victims’ commissioner for England and Wales, Dame Vera Baird, said the new low in CPS figures meant at least 1,000 fewer rapists were being prosecuted than two years ago, a fact that was “utterly shameful”. She has previously said that rape had in effect been decriminalised.

Sarah Green, director of EVAW, said: “Today’s figures show starkly that we are right to say rape has been effectively decriminalised. What else can you call a one in 70 chance of prosecution? The DPP’s constant exhortation to victims that they must come forward is frankly too much to take.”