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Law enforcement agencies across the UK effectively campaigned to use a face scanning system known to be biased against females, young people, and members of minority ethnic backgrounds, following complaints that a less biased version generated a reduced number of potential suspects.

How the System Works

British police utilize the national police database to conduct searches using historical face recognition. This process entails comparing a “probe image” of a suspect against a database of over 19 million mugshots to find potential matches.

Admitted Bias

The Home Office admitted last week that the technology was biased. This acknowledgment followed a review by the government's National Physical Laboratory determined it misidentified people of Black and Asian heritage and women at significantly higher rates than white men. The Home Office stated it “took steps on the findings”.

“This raises the question of whether facial recognition only becomes useful if users tolerate discrimination in race and sex. Convenience is a poor argument for overriding basic freedoms.”

Known Issue

Internal documents show that this bias has been known about for more than a year. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to mitigate the problem.

Senior officers were informed of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review concluded the system was had a higher probability to suggest incorrect matches for photos of women, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

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

However, this directive was reversed the following month following complaints from police that the modified technology was producing a lower number of “useful lines of inquiry”. NPCC documents indicate the higher threshold cut the number of searches resulting in potential matches from 56% to a mere 14%.

Severe Disparities

Although the authorities declined to specify what setting is now in operation, the latest independent review discovered the system could produce false positives for women of Black heritage nearly a hundred times more frequently than for Caucasian women at certain settings.

The ministry commented on these results: “Our evaluation found that in a specific scenarios 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 accuracy setting, the NPCC documents note: “The change significantly reduces the effect of discrimination across protected characteristics of race, age and gender but had a substantially detrimental effect on operational effectiveness”. The documents add that forces argued that “a previously useful tool returned results of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a ten-week consultation on its proposals to widen the use of biometric scanning systems. The minister for police Sarah Jones has described the tool as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the independent scrutiny and oversight board for the national policing equality strategy, said: “We observed very little discussion in race action plan meetings of the facial recognition rollout despite clear relevance with the plan’s concerns.

“This disclosure show once again that the anti-racism commitments policing has undertaken through the equality initiative are not being translated into broader operations. Independent assessments have cautioned that innovative tools are being rolled out in a context where ethnic inequalities, weak scrutiny and faulty information gathering continue to exist.

“Any use of this technology must adhere to strict national standards, be subject to external review, and demonstrate it diminishes rather than exacerbates racial disparity.”

Official Statement

A Home Office spokesperson stated: “The Home Office treat the conclusions of the report seriously and we have implemented changes. A updated software has been independently tested and acquired, which has no statistically significant bias. It will be tested in the coming months and will be undergo evaluation.

“Our priority is protecting the public. This gamechanging technology 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 taken without trained officers carefully reviewing the results.”