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Police forces across the United Kingdom successfully lobbied to use a face scanning system acknowledged as biased against females, youths, and members of ethnic minority groups, after complaining that a less biased version generated a reduced number of investigative leads.

How the System Works

UK forces utilize the police national database (PND) to carry out searches using historical face recognition. This procedure entails matching a “probe image” of a person of interest against a database of over 19 million custody photos to identify possible hits.

Admitted Bias

The Home Office admitted last week that the system was biased. This acknowledgment came after a study by the government's National Physical Laboratory found it incorrectly matched people of Black and Asian heritage and women at much greater frequency than white men. The Home Office said it “took steps on the findings”.

“It prompts the question of whether this technology only becomes effective if users tolerate discrimination in ethnicity and sex. Convenience is a weak argument for overriding fundamental rights.”

Known Issue

Official papers reveal that this bias has been recognized for over twelve months. Furthermore, police forces argued to overturn an earlier ruling that was designed to mitigate the problem.

Senior officers were informed of the system's bias in September 2024. The Home Office-commissioned laboratory study found the system was more likely to produce incorrect matches for images depicting females, Black people, and those under 40 years old.

A Policy U-Turn

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

However, this directive was reversed the following month after forces complained that the adjusted system was generating fewer “investigative leads”. Internal records show the higher threshold cut the number of searches that yielded possible identifications from 56% to a mere under 15%.

Severe Disparities

Although the Home Office and NPCC declined to specify what threshold is now in operation, the recent NPL study found the system could produce false positives for women of Black heritage nearly a hundred times more often than for Caucasian women at certain settings.

The ministry stated on these results: “Our evaluation identified that in a limited set of circumstances the software is more likely to incorrectly include some population segments in its match reports.”

Operational Effectiveness vs. Bias

Outlining the effect of the brief increase to the system's accuracy setting, the NPCC documents note: “This adjustment significantly reduces the impact of discrimination across protected characteristics of ethnicity, generation and gender but had a substantially detrimental effect on police efficiency”. The papers add that forces argued that “a previously useful tool now delivered outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the government has opened a two-and-a-half-month public review on its proposals to expand the use of facial recognition technology. Policing minister Sarah Jones has described the technology as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the advisory panel for the police race action plan, said: “We observed scant discussion through equality strategy sessions of the facial recognition rollout despite clear relevance with the plan’s concerns.

“These revelations demonstrate yet again that the anti-racism commitments the police has made via the race action plan are not being translated into wider practice. Independent assessments have warned that innovative tools are being implemented in a context where ethnic inequalities, weak scrutiny and faulty information gathering continue to exist.

“All deployment of facial recognition must adhere to strict national standards, be subject to external review, and demonstrate it reduces rather than exacerbates ethnic bias.”

Official Statement

A government representative stated: “We takes the findings of the report seriously and we have already taken action. A updated software has been independently tested and procured, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be subject to evaluation.

“Our priority is protecting the public. This gamechanging technology will assist police to put criminals and rapists behind bars. There is human involvement in every step of the procedure and no arrest or charge would be taken without trained officers carefully reviewing the output.”