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Police forces across the UK successfully lobbied to deploy a face scanning system acknowledged as discriminatory against women, young people, and individuals from ethnic minority groups, after complaining that a less biased version generated a reduced number of investigative leads.

The Technology in Practice

British police use the national police database to carry out searches using historical face recognition. This process involves matching a reference photograph of a person of interest against a repository of over 19 million mugshots to identify possible hits.

Admitted Bias

The UK interior ministry admitted last week that the system was flawed. This acknowledgment came after a review by the National Physical Laboratory (NPL) determined it misidentified Black and Asian people and females at significantly higher rates than white men. The ministry said it “had acted on the findings”.

“It prompts the issue of whether this technology only becomes useful if users accept biases in race and gender. Convenience is a poor argument for overriding fundamental rights.”

Known Issue

Official papers show that this bias has been recognized for more than a year. Furthermore, law enforcement lobbied to reverse an initial decision that was designed to mitigate the problem.

Police bosses were notified of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review concluded the system was more likely to produce false positives for photos of females, Black people, and those aged 40 and under.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for possible hits be raised to a point where the disparity was greatly diminished.

However, this directive was reversed the next month after forces complained that the modified technology was producing a lower number of “investigative leads”. Internal records show the stricter setting cut the number of searches resulting in possible identifications from over half to a just under 15%.

Severe Disparities

Although the Home Office and NPCC refused to say what threshold is now in operation, the recent NPL study discovered the system could produce incorrect matches for Black women almost 100 times more frequently than for white women at specific configurations.

The Home Office stated on these results: “The testing found that in a specific scenarios the software is has a greater tendency to wrongly flag some demographic groups in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's accuracy setting, the police records note: “The change greatly lessens the impact of discrimination across protected characteristics of race, generation and sex but had a substantially detrimental effect on police efficiency”. The papers further note that forces argued that “a previously useful tool now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has opened a ten-week consultation on its plans to expand the use of facial recognition technology. The minister for police the relevant minister has described the technology as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the independent scrutiny and oversight board for the police race action plan, said: “There was very little discussion through race action plan meetings of the technology deployment even with obvious cross-over with the strategy's goals.

“This disclosure demonstrate yet again that the anti-racism commitments policing has undertaken through the equality initiative are not being translated into broader operations. Our reports have cautioned that innovative tools are being implemented in a context where ethnic inequalities, inadequate oversight and poor data collection already persist.

“All deployment of facial recognition must meet strict national standards, be subject to external review, and prove it reduces rather than compounds racial disparity.”

Home Office Response

A Home Office spokesperson stated: “The Home Office treat the findings of the report seriously and we have already taken action. A updated software has been independently tested and acquired, which has no statistically significant bias. It will be tested in the coming months and will be undergo further assessment.

“The foremost aim is ensuring public safety. This gamechanging technology will support police to apprehend and prosecute offenders. There is officer review in every step of the process and no further action would be taken without trained officers meticulously examining the output.”