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Police forces across the United Kingdom successfully lobbied to use a facial recognition system acknowledged as biased against women, youths, and members of minority ethnic backgrounds, after complaining that a more accurate version generated fewer potential suspects.

How the System Works

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 identify possible hits.

Admitted Bias

The UK interior ministry conceded last week that the technology was flawed. This acknowledgment came after a study by the government's National Physical Laboratory determined it incorrectly matched people of Black and Asian heritage and females at significantly higher rates than Caucasian males. The Home Office stated it “took steps on the findings”.

“This raises the issue of whether this technology only becomes useful if users tolerate discrimination in ethnicity and sex. Convenience is a weak argument for overriding fundamental rights.”

Long-Standing Problem

Official papers show that this bias has been known about for over twelve months. Furthermore, police forces argued to overturn an earlier ruling that was intended to mitigate the problem.

Senior officers were notified of the system's bias in September 2024. The Home Office-commissioned NPL review concluded the system was had a higher probability to produce false positives for photos of females, 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 possible hits be increased to a point where the bias was significantly reduced.

However, this directive was overturned the next month following complaints from police that the modified technology was generating a lower number of “useful lines of inquiry”. Internal records show the higher threshold cut the proportion of queries that yielded potential matches from over half to a mere under 15%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what setting is currently used, the latest NPL study found the system could produce false positives for Black women nearly a hundred times more often 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 software is more likely to incorrectly include some population segments in its search results.”

Balancing Utility and Fairness

Describing the impact of the temporary raise to the system's accuracy setting, the police records note: “The change significantly reduces the impact of bias across legally safeguarded attributes of race, age and gender but had a substantially detrimental effect on operational effectiveness”. The papers further note that forces argued that “a previously useful tool returned outcomes of limited benefit”.

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 Sarah Jones has labeled the technology as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the advisory panel for the national policing equality strategy, said: “We observed very little discussion through race action plan meetings of the facial recognition rollout even with clear relevance with the strategy's goals.

“This disclosure demonstrate once again that the anti-racism commitments the police has made through the race action plan are failing to be integrated into wider practice. Our reports have warned that innovative tools are being rolled out in a landscape where ethnic inequalities, weak scrutiny and poor data collection already persist.

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

Official Statement

A government representative stated: “The Home Office takes the findings of the study seriously and we have implemented changes. A updated software has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be trialled early next year and will be subject to evaluation.

“The foremost aim is protecting the public. This revolutionary tool will support police to put criminals and rapists behind bars. There is officer review in every step of the procedure and no arrest or charge would be pursued without specialist personnel meticulously examining the output.”