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Police forces across the UK successfully lobbied to deploy a facial recognition system known to be discriminatory against women, young people, and members of minority ethnic backgrounds, after complaining that a less biased version generated fewer potential suspects.

The Technology in Practice

British police use the national police database to conduct searches using historical face recognition. This procedure involves matching a “probe image” of a person of interest against a database of more than 19 million custody photos to find potential matches.

Acknowledged Discrimination

The Home Office conceded last week that the system was flawed. This acknowledgment came after a study by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and women at significantly higher rates than Caucasian males. The Home Office said it “took steps on the findings”.

“It prompts the question of whether this technology only becomes effective if users accept biases in ethnicity and gender. Convenience is a poor argument for overriding basic freedoms.”

Long-Standing Problem

Official papers reveal that this discriminatory flaw has been recognized for over twelve months. Furthermore, law enforcement lobbied to reverse an initial decision that was designed to mitigate the problem.

Senior officers were notified of the algorithmic discrimination in September 2024. The government-ordered 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 confidence threshold required for potential matches be raised to a level where the disparity was significantly reduced.

However, this decision was reversed the following month after forces complained that the adjusted system was generating fewer “investigative leads”. Internal records indicate the higher threshold cut the proportion of searches that yielded potential matches from 56% to a just under 15%.

Severe Disparities

Although the authorities refused to say what threshold is now in operation, the latest independent review discovered the system could generate incorrect matches for women of Black heritage nearly a hundred times more frequently than for white women at specific configurations.

The Home Office commented on these results: “Our evaluation found that in a limited set of circumstances the algorithm is more likely to incorrectly include some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Outlining the impact of the brief increase to the system's confidence threshold, the NPCC documents note: “The change significantly reduces the impact of bias across legally safeguarded attributes of race, generation and gender but had a significant negative impact on police efficiency”. The papers further note that police units complained that “a once effective tactic returned outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the government has launched a two-and-a-half-month consultation on its plans to widen the use of biometric scanning systems. The minister for police the relevant minister has described the technology as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the independent scrutiny and oversight board for the police race action plan, commented: “We observed scant 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 pledges to combat discrimination the police has undertaken through the equality initiative are not being translated into broader operations. Our reports have warned that innovative tools are being rolled out in a landscape where ethnic inequalities, inadequate oversight and faulty information gathering continue to exist.

“All deployment of this technology must meet rigorous official guidelines, be subject to external review, and prove it diminishes rather than exacerbates racial disparity.”

Official Statement

A Home Office spokesperson said: “We takes the conclusions of the study with utmost gravity and we have already taken action. A new algorithm has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be subject to further assessment.

“Our priority is protecting the public. This revolutionary tool will assist officers to apprehend and prosecute offenders. There is officer review in every step of the process and no further action would be pursued without specialist personnel meticulously examining the output.”