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Law enforcement agencies across the United Kingdom effectively campaigned to use a face scanning system acknowledged as biased against women, young people, and members of minority ethnic backgrounds, following complaints that a less biased version produced fewer potential suspects.

How the System Works

UK forces use the national police database to carry out searches using historical face recognition. This procedure entails matching a reference photograph of a person of interest against a database of over 19 million mugshots to find possible hits.

Acknowledged Discrimination

The Home Office admitted last week that the system was flawed. This acknowledgment came after a review by the National Physical Laboratory (NPL) determined it misidentified Black and Asian people and females at significantly higher rates than white men. The Home Office stated it “had acted on the findings”.

“This raises the issue of whether this technology only becomes effective if users accept biases in ethnicity and sex. Operational ease is a weak argument for overriding basic freedoms.”

Known Issue

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

Police bosses were informed of the system's bias in late 2024. The government-ordered NPL review found the system was had a higher probability to produce false positives for images depicting 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 raised to a level where the bias was greatly diminished.

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”. Internal records show the stricter setting cut the number of queries resulting in possible identifications from over half to a mere under 15%.

Severe Disparities

Although the authorities refused to say what setting is now in operation, 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 certain settings.

The ministry commented on these results: “The testing identified that in a specific scenarios the software is has a greater tendency to wrongly flag some demographic groups in its search results.”

Balancing Utility and Fairness

Describing the effect of the brief increase to the system's confidence threshold, the NPCC documents state: “The change significantly reduces the effect of discrimination across legally safeguarded attributes of ethnicity, age and sex but had a significant negative impact on operational effectiveness”. The documents further note that police units complained that “a previously useful tool now delivered outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a ten-week consultation on its plans to widen the use of biometric scanning systems. Policing minister the relevant minister has labeled the tool as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the independent scrutiny and oversight board for the national policing equality strategy, said: “There was very little consideration in race action plan meetings of the facial recognition rollout despite clear relevance with the strategy's goals.

“These revelations demonstrate yet again that the pledges to combat discrimination the police has made through the equality initiative are failing to be integrated into wider practice. Our reports have warned that new technologies are being implemented in a landscape where ethnic inequalities, weak scrutiny and faulty information gathering already persist.

“All deployment of this technology must adhere to rigorous official guidelines, be subject to external review, and prove it diminishes rather than exacerbates ethnic bias.”

Home Office Response

A government representative stated: “We treat the conclusions of the report seriously and we have already taken action. A new algorithm has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be tested in the coming months and will be undergo evaluation.

“The foremost aim is ensuring public safety. This gamechanging technology will support officers to apprehend and prosecute offenders. There is human involvement in every step of the process and no arrest or charge would be pursued without trained officers carefully reviewing the output.”