The system for handling police complaints has been labelled as “broken” by critics after it was found 43 per cent of officers deemed as having a case to answer for misconduct faced no further action.

The Independent Office for Police Conduct (IOPC) was set up in 2018 to reform the way complaints were handled, by improving the speed in which conclusions were given.

But of 1,895 investigations it has carried out, only 881 have been published on its website, and questions have been asked about whether it has increased the speed of investigations, made them more independent and improved justice.

Since 2018, the IOPC has published one investigation into misconduct at Wiltshire Police – which was proven and the police staff member was given management action.

The member of staff was responsible for responding to applications under Clare’s Law – which allows people to request disclosure of a person’s history of abusive behaviour.

Given the date of birth the applicant provided, which turned out to be incorrect, two computer checks were completed, which showed there were no matches.

But a month later, the woman was assaulted at a hotel by her partner and sustained a number of injuries. It was later established that her partner had a “documented history of domestic abuse”, and further checks should have identified this.

Overall, data obtained by the BBC and shared with the Adver shows that over the past three years, some 418 misconduct cases were held by forces following an initial investigation by the IOPC.

The force panels subsequently found officers or staff to have committed misconduct or gross misconduct in 266 (64%) of cases.

In misconduct cases, panels gave 18 final written warnings, 57 written warnings, took management action in 50 cases and took no further action in 12 cases.

Reacting to the findings, award-winning documentary maker Ken Fero, who campaigns on behalf of families whose loved ones have died in police custody, known as the United Families and Friends Coalition, said: “If we go back historically to when we first started working around this issue, which was around the early 90s really, at that time there was the Police Complaints Authority (PCA), which was basically an internal investigation system.

“It’s a very similar state of affairs to where we are now with the IOPC, which has again shown an absolute failure to investigate things properly and the family is not allowed to be part of the process.

“The only three prosecutions that we’ve had as a result of a death of a member of the public have been in the cases of Sarah Everard, Dalian Atkinson and Henry Foley, which was a case from the 1980s.

“Apart from that there’s been over 2,000 documented deaths at the hands of the police and only three prosecutions. The PCA, the IPCC and the IOPC are a fundamental part of the failure of the State to hold officers to account.

“The data you have really supports what the families have been saying for a long time which is that the system is broken.”

Meanwhile, Police Federation of England and Wales National Vice Chair Ché Donald said: “It is vital we have an independent, impartial body that has oversight over policing so officers are rightly held accountable for their actions, but the IOPC often inexplicably pursues vexatious allegations, which may be a reason why a significant proportion of cases have resulted in no further action.”

Director of strategy and input at the IOPC, Kathie Cashell, questioned where the evidence is that they pursue vexatious allegations.

She said: “When you look at things that stopped short of misconduct proceedings - so unsatisfactory performance or reflective action procedures - 60% of the individuals we investigated needed some form of action after those cases. Police forces agreed with us on 64% of occasions. I just don’t see where the evidence is that the IOPC is pursuing vexatious allegations.

“I think sanctions do play a role but I think accountability takes many forms. Answering for your actions and explaining them in public is accountability itself. I don’t think misconduct sanctions are the only measure of performance in this system, but I agree they are important.

“I do think it’s really important that those panels operate consistently and the rationale behind the decisions they make are transparent. We would welcome a review that looks into whether they are consistent and transparent.”