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Police forces across the UK effectively campaigned to use a facial recognition system acknowledged as discriminatory against women, young people, and individuals from minority ethnic backgrounds, after complaining that a more accurate version generated fewer potential suspects.

The Technology in Practice

British police use the national police database to carry out searches using historical face recognition. This process entails matching a reference photograph of a person of interest against a repository of over 19 million custody photos to identify potential matches.

Admitted Bias

The Home Office admitted last week that the system was flawed. This admission followed a review by the National Physical Laboratory (NPL) found it incorrectly matched people of Black and Asian heritage and females at significantly higher rates than white men. The Home Office said it “took steps on the findings”.

“This raises the question of whether facial recognition only becomes effective if users accept discrimination in ethnicity and sex. Convenience is a poor argument for disregarding basic freedoms.”

Known Issue

Internal documents reveal that this discriminatory flaw 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 notified of the system's bias in September 2024. The government-ordered laboratory study concluded the system was more likely to suggest false positives for images depicting females, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In response, the national police leadership body mandated that the confidence threshold required for potential matches be increased to a point where the bias was greatly diminished.

However, this decision was reversed the following month following complaints from police that the modified technology was producing fewer “investigative leads”. NPCC documents indicate the higher threshold cut the proportion of queries that yielded potential matches from 56% to a just under 15%.

Severe Disparities

Although the authorities declined to specify what threshold is now in operation, the latest NPL study found the system could generate false positives for women of Black heritage nearly a hundred times more often than for white women at specific configurations.

The ministry stated on these findings: “Our evaluation found that in a specific scenarios the algorithm 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 accuracy setting, the NPCC documents state: “This adjustment significantly reduces the effect of discrimination across protected characteristics of ethnicity, generation and gender but had a substantially detrimental effect on police efficiency”. The documents further note that police units complained that “a previously useful tool returned outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a ten-week public review on its proposals to widen the use of facial recognition technology. Policing minister the relevant minister has described the technology as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the independent scrutiny and oversight board for the national policing equality strategy, said: “We observed very little consideration through race action plan meetings of the technology deployment despite clear relevance with the strategy's goals.

“This disclosure show yet again that the pledges to combat discrimination policing has undertaken through the equality initiative are not being translated into wider practice. Our reports have cautioned that new technologies are being rolled out in a context where ethnic inequalities, inadequate oversight and poor data collection already persist.

“Any use of facial recognition must adhere to strict national standards, be independently scrutinised, and demonstrate it diminishes rather than compounds racial disparity.”

Official Statement

A Home Office spokesperson said: “The Home Office treat the findings of the report seriously and we have implemented changes. A new algorithm has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be trialled early next year and will be subject to evaluation.

“The foremost aim is ensuring public safety. This revolutionary tool 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 carefully reviewing the results.”