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Police forces across the UK effectively campaigned to use a facial recognition system known to be discriminatory against women, youths, and individuals from minority ethnic backgrounds, after complaining that a less biased version produced fewer potential suspects.

How the System Works

British police use the national police database to conduct retrospective facial recognition searches. This procedure entails comparing a “probe image” of a suspect against a database of more than 19 million mugshots to identify potential matches.

Admitted Bias

The Home Office conceded last week that the system was flawed. This admission followed a study by the National Physical Laboratory (NPL) found it misidentified people of Black and Asian heritage and women at much greater frequency than Caucasian males. The ministry stated it “took steps on the findings”.

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

Known Issue

Official papers reveal that this bias has been known about for over twelve months. Furthermore, police forces lobbied to reverse an initial decision that was designed to mitigate the problem.

Police bosses were notified of the system's bias in September 2024. The Home Office-commissioned laboratory study found the system was more likely to suggest incorrect matches for photos of women, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

In reaction, the national police leadership body ordered that the confidence threshold required for potential matches be increased to a point where the disparity was significantly reduced.

However, this decision was overturned the following month following complaints from police that the adjusted system was producing a lower number of “investigative leads”. NPCC documents indicate the stricter setting cut the proportion of searches that yielded possible identifications from over half to a mere 14%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what threshold is currently used, the latest NPL study discovered the system could generate incorrect matches for Black women almost 100 times more frequently than for Caucasian women at certain settings.

The ministry stated on these results: “Our evaluation found that in a limited set of circumstances the software is has a greater tendency to incorrectly include some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Describing the effect of the temporary raise to the system's accuracy setting, the police records state: “This adjustment significantly reduces the impact of discrimination across protected characteristics of race, age and sex but had a significant negative impact on operational effectiveness”. The documents add that forces argued that “a once effective tactic now delivered results of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a two-and-a-half-month consultation on its proposals to widen the use of facial recognition technology. The minister for police the relevant minister has described the tool as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the advisory panel for the national policing equality strategy, said: “There was scant discussion through race action plan meetings of the technology deployment even with clear relevance with the strategy's goals.

“This disclosure show once again that the anti-racism commitments policing has made through the equality initiative are failing to be integrated into wider practice. Independent assessments have cautioned that innovative tools are being implemented in a landscape where ethnic inequalities, inadequate oversight and faulty information gathering continue to exist.

“Any use of this technology must adhere to strict national standards, be independently scrutinised, and demonstrate it diminishes rather than compounds ethnic bias.”

Home Office Response

A government representative said: “We treat the findings of the report with utmost gravity and we have already taken action. A new algorithm has been externally evaluated and procured, which has no statistically significant bias. It will be tested early next year and will be undergo evaluation.

“Our priority is ensuring public safety. This gamechanging technology will assist officers to put criminals and rapists behind bars. There is human involvement in each stage of the process and no arrest or charge would be pursued without trained officers carefully reviewing the output.”