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Police forces across the UK successfully lobbied to deploy a facial recognition system acknowledged as discriminatory against women, youths, and individuals from ethnic minority groups, following complaints that a less biased version generated a reduced number of potential suspects.

The Technology in Practice

British police use the police national database (PND) to carry out searches using historical face recognition. This procedure entails comparing a “probe image” of a person of interest against a repository of over 19 million mugshots to find potential matches.

Admitted Bias

The Home Office conceded last week that the system was biased. This admission followed a review by the government's National Physical Laboratory determined 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 issue of whether facial recognition only becomes effective if users accept discrimination in ethnicity and gender. Convenience is a poor argument for overriding fundamental rights.”

Known Issue

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

Senior officers were informed of the algorithmic discrimination in September 2024. The government-ordered laboratory study concluded the system was had a higher probability to suggest false positives for photos of females, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In reaction, the national police leadership body ordered that the confidence threshold required for possible hits be raised to a level where the bias was greatly diminished.

However, this directive was overturned the following month following complaints from police that the modified technology was generating a lower number of “useful lines of inquiry”. NPCC documents show the higher threshold cut the number of searches resulting in possible identifications from over half to a mere 14%.

Profound Inequalities

Although the authorities declined to specify what threshold is now in operation, the latest independent review discovered the system could produce false positives for Black women almost 100 times more frequently than for Caucasian women at specific configurations.

The ministry stated on these findings: “Our evaluation found that in a specific scenarios the algorithm is more likely to wrongly flag some demographic groups in its match reports.”

Balancing Utility and Fairness

Describing the impact of the brief increase to the system's confidence threshold, the NPCC documents note: “The change significantly reduces the impact of bias across protected characteristics of race, age and sex but had a substantially detrimental effect on police efficiency”. The papers further note that police units argued that “a previously useful tool now delivered results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a two-and-a-half-month public review on its plans to widen the use of biometric scanning systems. The minister for police Sarah Jones has labeled the tool as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the advisory panel for the national policing equality strategy, commented: “There was very little consideration through equality strategy sessions of the facial recognition rollout despite obvious cross-over with the strategy's goals.

“This disclosure show once again that the anti-racism commitments policing has made via the equality initiative are not being translated into wider practice. Independent assessments have cautioned that innovative tools are being implemented in a landscape where racial disparities, weak scrutiny and poor data collection already persist.

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

Home Office Response

A government representative stated: “The Home Office treat the conclusions of the report seriously and we have already taken action. A updated software has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be trialled 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 apprehend and prosecute offenders. There is human involvement in each stage of the process and no arrest or charge would be pursued without specialist personnel meticulously examining the results.”