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Law enforcement agencies across the United Kingdom effectively campaigned to use a face scanning system known to be biased against women, young people, and members of minority ethnic backgrounds, following complaints that a more accurate version generated fewer investigative leads.

The Technology in Practice

UK forces utilize the national police database to conduct searches using historical face recognition. This process entails matching a reference photograph of a suspect against a repository of more than 19 million mugshots to identify possible hits.

Acknowledged Discrimination

The UK interior ministry admitted last week that the system was biased. This acknowledgment followed a review by the National Physical Laboratory (NPL) found it incorrectly matched people of Black and Asian heritage and women at significantly higher rates than Caucasian males. The ministry stated it “took steps on the findings”.

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

Long-Standing Problem

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

Senior officers were informed of the algorithmic discrimination in September 2024. The government-ordered NPL review found the system was more likely to suggest false positives for images depicting women, Black people, and those aged 40 and under.

A Policy U-Turn

In reaction, the national police leadership body mandated that the accuracy setting required for potential matches be raised to a point where the disparity was significantly reduced.

However, this directive was reversed the next month following complaints from police that the adjusted system was generating a lower number of “useful lines of inquiry”. NPCC documents indicate the stricter setting reduced the number of searches that yielded potential matches from 56% to a just under 15%.

Profound Inequalities

Although the authorities declined to specify what threshold is currently used, the recent independent review found the system could produce false positives for Black women nearly a hundred times more often than for Caucasian women at specific configurations.

The ministry commented on these results: “Our evaluation identified that in a limited set of circumstances the algorithm is more likely to incorrectly include some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Outlining the effect of the temporary raise to the system's confidence threshold, the NPCC documents note: “The change greatly lessens the effect of discrimination across protected characteristics of ethnicity, age and gender but had a substantially detrimental effect on operational effectiveness”. The documents further note that police units argued that “a once effective tactic now delivered results of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a ten-week public review on its proposals to widen the use of biometric scanning systems. The minister for police the relevant minister has labeled the technology as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the advisory panel for the national policing equality strategy, said: “There was very little consideration in equality strategy sessions of the technology deployment even with obvious cross-over with the plan’s concerns.

“This disclosure show once again that the anti-racism commitments the police has undertaken via the race action plan are failing to be integrated into broader operations. Our reports have warned that innovative tools are being implemented in a context where ethnic inequalities, weak scrutiny and faulty information gathering already persist.

“Any use of this technology must meet strict national standards, be independently scrutinised, and demonstrate it diminishes rather than exacerbates racial disparity.”

Home Office Response

A Home Office spokesperson stated: “We treat the findings of the study with utmost gravity and we have implemented changes. A updated software has been independently tested and procured, which has no statistically significant bias. It will be tested in the coming months and will be subject to further assessment.

“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 each stage of the process and no further action would be pursued without specialist personnel meticulously examining the results.”