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Law enforcement agencies across the United Kingdom successfully lobbied to use a face scanning system known to be discriminatory against women, youths, and members of minority ethnic backgrounds, following complaints that a less biased version produced a reduced number of investigative leads.

How the System Works

UK forces utilize the police national database (PND) to carry out searches using historical face recognition. This procedure involves matching a “probe image” of a person of interest against a database of over 19 million mugshots to identify potential matches.

Admitted Bias

The Home Office admitted last week that the system was biased. This admission followed a study by the National Physical Laboratory (NPL) determined it incorrectly matched Black and Asian people and women at much greater frequency than Caucasian males. The Home Office stated it “took steps on the findings”.

“This raises the question of whether facial recognition only becomes effective if users accept biases in ethnicity and gender. Convenience is a poor argument for disregarding basic freedoms.”

Long-Standing Problem

Internal documents show that this bias has been known about for more than a year. Furthermore, police forces lobbied to reverse an initial decision that was designed to address the problem.

Police bosses were informed of the algorithmic discrimination in September 2024. The Home Office-commissioned laboratory study concluded the system was had a higher probability to suggest false positives for images depicting women, Black people, and those aged 40 and under.

A Policy U-Turn

In response, the national police leadership body mandated that the accuracy setting required for potential matches be raised to a point where the disparity was greatly diminished.

However, this decision was overturned the next month after forces complained that the adjusted system was producing a lower number of “useful lines of inquiry”. Internal records show the stricter setting reduced the proportion of searches resulting in possible identifications from 56% to a just under 15%.

Severe Disparities

Although the Home Office and NPCC refused to say what setting is currently used, the latest independent review found the system could produce incorrect matches for Black women nearly a hundred times more frequently than for Caucasian women at specific configurations.

The ministry commented on these results: “The testing found that in a specific scenarios the software is more likely to incorrectly include some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Outlining the effect of the temporary raise to the system's confidence threshold, the police records note: “This adjustment significantly reduces the impact of bias across protected characteristics of ethnicity, age and sex but had a substantially detrimental effect on operational effectiveness”. The papers further note that forces complained that “a previously useful tool now delivered results of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a ten-week consultation on its plans to widen the use of biometric scanning systems. The minister for police Sarah Jones has described the technology as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the advisory panel for the police race action plan, said: “There was very little discussion in equality strategy sessions of the technology deployment despite obvious cross-over with the plan’s concerns.

“This disclosure demonstrate once again that the anti-racism commitments the police has undertaken through the race action plan are failing to be integrated into broader operations. Our reports have warned that innovative tools are being implemented in a landscape where racial disparities, inadequate oversight and poor data collection already persist.

“All deployment of facial recognition must meet rigorous official guidelines, be independently scrutinised, and demonstrate it diminishes rather than exacerbates ethnic bias.”

Home Office Response

A Home Office spokesperson stated: “We takes the findings of the study seriously and we have already taken action. A new algorithm has been externally evaluated and acquired, which has no statistically significant bias. It will be tested in the coming months and will be subject to evaluation.

“Our priority is protecting the public. This gamechanging technology will support police to put criminals and rapists behind bars. There is human involvement in each stage of the process and no further action would be taken without trained officers carefully reviewing the results.”