The Crown Prosecution Service (CPS) has published its performance statistics on sexual violence cases for the year 2019-20. They make shocking reading.

The number of prosecutions for rape is down to its lowest level since annual recording began – 2,102 in England and Wales compared with 3,034 in 2018-19 – a drop of 30% in a single year.

The number of convictions is also at its lowest level and is down a quarter, at just 1,439, about half of what it was two years ago. The number of rape cases charged has risen slightly, but is still significantly less than recorded in the years leading up to 2018.

These figures are utterly shameful. To put them into context, police-recorded rape offences have more than doubled over six years to 55,130 in 2019-20.. Yet the vast majority of those reporting rape will never get justice; their cases will not get even as far as a courtroom.

What we are witnessing is the decriminalisation of rape. In the process, we are failing to give justice to thousands of complainants. In some cases, we are enabling persistent predatory sex offenders to go on to reoffend in the knowledge that they are highly unlikely to be held to account.

This is likely to mean we are creating more victims as a result of our failure to act.

The start of this this dramatic fall coincides with the moment, in September 2016, when the CPS director of legal services, Greg McGill, wrote a document called Decision-making in Rasso Cases, expressing a wish to “lift the conviction rate”, which could be achieved by taking “weaker cases” out of the system. He cautioned in the document that a change in the approach to decision-making on when to bring charges may lead to “overcorrection and a failure to prosecute” – yet the CPS drove this change of practice regardless.

At workshops, prosecutors were reportedly urged to adopt a “touch on the tiller” against prosecuting “difficult” rape cases. They were allegedly told to “take 350 weak cases” a year out of the system in order to increase the overall conviction rate to 60%-plus and the conviction after trial rate to 50%-plus.

Speaking on the BBC this week, deputy chief constable Sarah Crew, who leads on rape for the National Police Chiefs’ Council, made it clear there has been a change in the CPS’s evidence test. Police officers have found it harder to achieve the standard of evidence now required to get a charge and get the suspect into court.

The results of the change in approach are stark. In the year ending March 2017, CPS charged 3,671 cases, in the next year they charged only 2,822 and in 2018/19 charges dropped to a mere 1,758 – a 52% decrease across the those years.

Meanwhile, police referrals remained steady at over 4,000 until 2018-19, when police recognised how few cases were being charged and referrals dropped to 3,375. The CPS change in practice had that knock-on effect on police referrals.

The CPS denies a change of prosecution policy, but so far, it has failed to offer any convincing explanation to account for the fall in the number of cases being prosecuted. Instead it has published a “five-year blueprint for prosecuting rape and serious sexual offences”, called Rape and Serious Sexual Offences (Rasso) 2025.

As the name suggests, this is a strategy targeting 2025. But rape complainants cannot wait another five years for change. The CPS must change the way it prosecutes rape now. After all, there is no complexity in why rape prosecutions and convictions have crashed.

Max Hill, the director of public prosecutions, could reverse that decline immediately. In fact, he has been asked to do so by rape campaigners for the entire time he has been in post.

For the sake of getting a higher rate of convictions, the CPS have cut the volume of cases they charge, leaving thousands of rape complainants without the chance of justice, even in instances when they appear to have a strong evidential case. The bowing to rape myths must end.

Victims of rape and sexual assault are being badly let down. Any victim of sexual violence must feel able to come forward and report in the knowledge they will be supported, treated with respect and given access to justice.

• Vera Baird is the victims’ commissioner for England and Wales