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Law enforcement agencies across the United Kingdom effectively campaigned to deploy a face scanning system acknowledged as biased against women, young people, and individuals from ethnic minority groups, after complaining that a more accurate version produced fewer potential suspects.

How the System Works

British police use the police national database (PND) to carry out retrospective facial recognition searches. This process entails matching a “probe image” of a person of interest against a database of more than 19 million custody photos to find possible hits.

Admitted Bias

The UK interior ministry admitted last week that the technology was biased. This acknowledgment came after a study by the government's National Physical Laboratory determined it misidentified people of Black and Asian heritage and females at significantly higher rates than white men. The Home Office said it “had acted on the findings”.

“This raises the question of whether this technology only becomes effective if users tolerate biases in ethnicity and sex. Convenience is a poor argument for disregarding fundamental rights.”

Known Issue

Official papers reveal that this discriminatory flaw has been recognized for over twelve months. Furthermore, law enforcement lobbied to reverse an earlier ruling that was designed to address the problem.

Police bosses were informed of the algorithmic discrimination in September 2024. The Home Office-commissioned laboratory study concluded the system was had a higher probability to produce false positives for images depicting females, Black people, and those aged 40 and under.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for possible hits be raised to a point where the disparity was significantly reduced.

However, this decision was reversed the following month following complaints from police that the modified technology was producing a lower number of “investigative leads”. NPCC documents indicate the stricter setting cut the number of queries resulting in potential matches from over half to a mere 14%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what threshold is now in operation, the latest independent review discovered the system could generate incorrect matches for women of Black heritage almost 100 times more often than for Caucasian women at specific configurations.

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

Operational Effectiveness vs. Bias

Outlining the impact of the temporary raise to the system's confidence threshold, the police records note: “This adjustment greatly lessens the impact of bias across protected characteristics of ethnicity, generation and sex but had a substantially detrimental effect on operational effectiveness”. The papers add that police units complained that “a previously useful tool now delivered results of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a two-and-a-half-month consultation on its proposals to widen the use of biometric scanning systems. The minister for police Sarah Jones 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 discussion through equality strategy sessions of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“These revelations show yet again that the anti-racism commitments policing has undertaken through the race action plan are not being translated into wider practice. Our reports have warned that new technologies are being rolled out in a landscape where ethnic inequalities, weak scrutiny and poor data collection already persist.

“All deployment of this technology must adhere to strict national standards, be independently scrutinised, and demonstrate it diminishes rather than exacerbates ethnic bias.”

Official Statement

A government representative said: “The Home Office treat the findings of the study seriously and we have already taken action. A updated software has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be tested in the coming months and will be subject to further assessment.

“Our priority is protecting the public. This gamechanging technology will assist police to apprehend and prosecute offenders. There is officer review in each stage of the process and no arrest or charge would be pursued without trained officers meticulously examining the output.”