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Police forces across the United Kingdom effectively campaigned to deploy a face scanning system acknowledged as discriminatory against women, youths, and members of minority ethnic backgrounds, after complaining that a less biased version produced fewer investigative leads.

How the System Works

British police utilize the police national database (PND) to conduct searches using historical face recognition. This process entails matching a “probe image” of a suspect against a repository of more than 19 million custody photos to find potential matches.

Admitted Bias

The Home Office admitted last week that the technology was flawed. This admission came after a study by the National Physical Laboratory (NPL) determined it misidentified people of Black and Asian heritage and women at much greater frequency than Caucasian males. The Home Office said it “had acted on the findings”.

“This raises the question of whether facial recognition only becomes effective if users accept biases in race and sex. Convenience is a weak argument for overriding basic freedoms.”

Known Issue

Internal documents reveal that this discriminatory flaw has been recognized for over twelve months. Furthermore, police forces lobbied to reverse an earlier ruling that was intended to address the problem.

Police bosses were notified of the algorithmic discrimination in September 2024. The government-ordered laboratory study found the system was had a higher probability to produce false positives for photos of females, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In reaction, the national police leadership body ordered that the confidence threshold required for possible hits be increased to a point where the disparity was significantly reduced.

However, this directive was reversed the following month following complaints from police that the adjusted system was generating fewer “useful lines of inquiry”. Internal records show the stricter setting reduced the proportion of searches that yielded potential matches from 56% to a mere 14%.

Profound Inequalities

Although the authorities refused to say what setting is now in operation, the latest NPL study found the system could generate false positives for women of Black heritage almost 100 times more often than for Caucasian women at specific configurations.

The Home Office commented on these findings: “The testing found that in a limited set of circumstances the software is has a greater tendency to wrongly flag some population segments in its match reports.”

Operational Effectiveness vs. Bias

Describing the effect of the temporary raise to the system's confidence threshold, the police records state: “The change significantly reduces the effect of discrimination across protected characteristics of ethnicity, age and sex but had a significant negative impact on police efficiency”. The documents further note that police units argued that “a once effective tactic returned outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a ten-week public review on its proposals to widen the use of biometric scanning systems. Policing minister the relevant minister has described 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 police race action plan, said: “There was very little consideration in race action plan meetings of the facial recognition rollout despite clear relevance with the strategy's goals.

“This disclosure demonstrate yet again that the pledges to combat discrimination policing has undertaken via the equality initiative are failing to be integrated into wider practice. Independent assessments have warned that innovative tools are being rolled out in a landscape where ethnic inequalities, inadequate oversight and faulty information gathering already persist.

“Any use of facial recognition must adhere to rigorous official guidelines, be subject to external review, and prove it diminishes 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 implemented changes. A new algorithm has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be trialled early next year and will be subject to evaluation.

“Our priority is ensuring public safety. This revolutionary tool will assist police to put criminals and rapists behind bars. There is human involvement in each stage of the process and no further action would be pursued without trained officers carefully reviewing the output.”