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Police forces across the United Kingdom successfully lobbied to use a facial recognition system known to be discriminatory against women, youths, and individuals from ethnic minority groups, following complaints that a more accurate version produced 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 procedure involves matching a “probe image” of a suspect against a repository of more than 19 million custody photos to identify potential matches.

Admitted Bias

The UK interior ministry admitted last week that the system was biased. This acknowledgment followed a review by the National Physical Laboratory (NPL) determined it misidentified people of Black and Asian heritage and females at significantly higher rates than Caucasian males. The ministry said it “had acted on the findings”.

“This raises the question of whether this technology only becomes effective if users tolerate discrimination in race and sex. Operational ease is a poor argument for disregarding basic freedoms.”

Long-Standing Problem

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

Police bosses were informed of the system's bias in late 2024. The Home Office-commissioned NPL review concluded the system was had a higher probability to produce incorrect matches for photos of women, Black people, and those aged 40 and under.

A Policy U-Turn

In response, the National Police Chiefs’ Council (NPCC) ordered that the confidence threshold required for possible hits be raised to a level where the disparity was significantly reduced.

However, this decision was overturned the following month after forces complained that the adjusted system was producing a lower number of “investigative leads”. NPCC documents show the higher threshold reduced the number of searches that yielded possible identifications from over half to a just 14%.

Profound Inequalities

Although the Home Office and NPCC refused to say what threshold is now in operation, the recent independent review discovered the system could generate incorrect matches for women of Black heritage nearly a hundred times more often than for white women at certain settings.

The Home Office commented on these results: “Our evaluation identified that in a specific scenarios the algorithm is has a greater tendency to incorrectly include some demographic groups in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's confidence threshold, the NPCC documents note: “This adjustment greatly lessens the effect of bias across protected characteristics of ethnicity, age and gender but had a significant negative impact on operational effectiveness”. The papers add that forces complained that “a once effective tactic now delivered outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has opened a two-and-a-half-month public review on its plans to expand the use of biometric scanning systems. The minister for police the relevant minister has labeled the tool as the “biggest breakthrough since DNA matching”.

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 scant consideration through equality strategy sessions of the facial recognition rollout despite obvious cross-over with the strategy's goals.

“This disclosure show yet again that the pledges to combat discrimination the police has made through the race action plan are not being translated into wider practice. Independent assessments have warned that innovative tools are being rolled out in a landscape where ethnic inequalities, weak scrutiny and faulty information gathering already persist.

“Any use of this technology must adhere to rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than compounds ethnic bias.”

Home Office Response

A government representative said: “We treat the findings of the study with utmost gravity and we have implemented changes. A updated software has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be tested in the coming months and will be undergo evaluation.

“The foremost aim is ensuring public safety. This gamechanging technology will support officers to put criminals and rapists behind bars. There is officer review in each stage of the process and no arrest or charge would be taken without trained officers meticulously examining the results.”