Police officers and staff in the country's biggest force expect to be victimised and have their careers damaged if they complain about discrimination, a report has found.
The Equality and Human Rights Commission (EHRC) investigated Scotland Yard's handling of complaints of race, gender and sexuality discrimination in the wake of a controversial case involving firearms officer Carol Howard. She was awarded £37,000 after being hounded by her boss for being a black woman.
Lead EHRC Commissioner for the investigation Laura Carstensen said: "It is unacceptable that police officers and staff often expect to be victimised if they complain about discrimination, and particularly so when this is the organisation to which all Londoners look for protection and fair treatment."
The Commission was unable to decide whether officers actually suffered after making a complaint, because "the quality of the Metropolitan Police Service's (MPS) data made it difficult to reach any conclusions".
Scotland Yard came under heavy criticism for the Howard case, in part after it revealed, in the wake of her victory, that she had been arrested over disagreements with her estranged partner. No charges were ever brought.
Employment judges accused the force of trying to "deflect'' negative publicity by releasing the details.
In a second case, where PC Daniel Lichters was taunted for being gay, the tribunal panel found that the force had "either set out to, or were reckless about destroying the claimant's character".
He faced baseless gross misconduct and criminal claims after his police dog bit a member of the public who attacked it.
The ECHR report found complaints that could have been resolved with an apology were instead escalated to focus on blame. This was partly due to confusion over the law, which currently binds the Met to immediately raise all complaints to consider misconduct by the alleged perpetrator.
Other complicating factors were a police culture of "looking after your own", and the force's "painful history" over racism.
Ms Carstensen said: "A willingness to be held to account and to apologise is crucial to any organisation and particularly to an essential and powerful public service such as the police. Our investigation raised concerns that the MPS do not demonstrate this behaviour in relation to their handling of internal complaints.
"Many of the individuals we spoke to said that their initially simple complaints could have been resolved quickly and effectively with an apology and an acceptance that things went wrong. However, the complex regulatory framework alongside police culture and the MPS's history in terms of race issues mean that this rarely happens. Instead, the focus has too often been on apportioning blame and issuing sanctions."
The report found that confusion over how the law should be applied to complaints left all police forces open to legal action, and recommended that legislation is updated.
It said that Scotland Yard's "approach to complaints of discrimination was inconsistent and confused", and that some managers struggled to deal with race complaints.
Deputy commissioner Craig Mackey said: "After nearly two years of investigation, the EHRC has confirmed that they have found no evidence of any unlawful acts in how the Met responds to staff grievances and complaints linked to discrimination or any evidence of systemic victimisation."
He said the report's conclusions "differ little" from an earlier review carried out by conciliation service Acas that was commissioned by force bosses, and that the Met "utterly reject" the suggestion that lack of data hampered the EHRC investigation.
Mr Mackey went on: "We have agreed to develop an enhanced plan to tackle the perceptions of victimisation identified by the Acas report.
"The widespread belief that those that complain will be victimised is undoubtedly the most troubling aspect to have emerged from this work.
"Neither report identified evidence of any widespread victimisation to support the perception and it is important to recognise that the number of people who raise allegations of discrimination, when compared to our workforce of 45,000 people, is very small - with only 37 people or 0.08% of staff alleging misconduct related to discrimination and 92 or 0.2% of our staff raising discrimination grievances last year."
Scotland Yard bosses are already in talks with the Home Office to make changes to the "impossible framework" that forces discrimination complaints to be treated as possible misconduct by the perpetrator.
They are also introducing enhanced training for those handling complaints.