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Police forces across the United Kingdom successfully lobbied to use a face scanning system acknowledged as biased against females, youths, and individuals from minority ethnic backgrounds, following complaints that a more accurate version produced fewer potential suspects.

The Technology in Practice

British police use the national police database to carry out retrospective facial recognition searches. This process involves comparing a “probe image” of a person of interest against a repository of over 19 million mugshots to find potential matches.

Admitted Bias

The UK interior ministry admitted last week that the technology was biased. This acknowledgment followed a study by the government's National Physical Laboratory determined it misidentified Black and Asian people and women at much greater frequency than white men. The Home Office stated it “took steps on the findings”.

“This raises the issue of whether facial recognition only becomes useful if users accept biases in ethnicity and gender. Operational ease is a poor argument for overriding fundamental rights.”

Known Issue

Official papers show that this discriminatory flaw has been known about for over twelve months. Furthermore, police forces argued to overturn an initial decision that was intended to address the problem.

Police bosses were notified of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review concluded the system was had a higher probability to suggest incorrect matches for photos of women, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In reaction, the national police leadership body ordered that the confidence threshold required for possible hits be increased to a point where the bias was greatly diminished.

However, this decision was reversed the next month following complaints from police that the modified technology was generating fewer “investigative leads”. Internal records show the higher threshold reduced the number of queries resulting in potential matches from over half to a mere under 15%.

Severe Disparities

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

The ministry commented on these findings: “Our evaluation identified that in a specific scenarios the algorithm is has a greater tendency to incorrectly include some population segments in its search results.”

Operational Effectiveness vs. Bias

Describing the effect of the temporary raise to the system's confidence threshold, the NPCC documents note: “This adjustment significantly reduces the impact of discrimination across protected characteristics of ethnicity, age and sex but had a significant negative impact on operational effectiveness”. The papers further note that police units complained that “a previously useful tool now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a ten-week public review on its plans to widen the use of facial recognition technology. Policing minister the relevant minister has described the technology as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the advisory panel for the police race action plan, commented: “We observed very little discussion through race action plan meetings of the technology deployment despite clear relevance with the plan’s concerns.

“This disclosure show yet again that the pledges to combat discrimination the police has undertaken through the equality initiative are failing to be integrated into broader operations. Independent assessments have cautioned that new technologies are being rolled out in a landscape where ethnic inequalities, inadequate oversight and poor data collection already persist.

“Any use of facial recognition must meet strict national standards, be independently scrutinised, and prove it diminishes rather than compounds racial disparity.”

Official Statement

A Home Office spokesperson said: “The Home Office treat the conclusions of the report 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 early next year and will be subject to further assessment.

“The foremost aim is protecting the public. This revolutionary tool will support officers to put criminals and rapists behind bars. There is human involvement in every step of the procedure and no further action would be pursued without trained officers carefully reviewing the output.”