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Law enforcement agencies across the UK successfully lobbied to use a face scanning system known to be discriminatory against females, youths, and individuals from minority ethnic backgrounds, following complaints that a more accurate version produced a reduced number of investigative leads.

The Technology in Practice

British police use the police national database (PND) to conduct retrospective facial recognition searches. This process involves comparing a “probe image” of a person of interest against a database of more than 19 million mugshots to find potential matches.

Admitted Bias

The Home Office admitted last week that the technology was flawed. This acknowledgment came after a review by the government's National Physical Laboratory determined it misidentified Black and Asian people and women at much greater frequency than white men. The Home Office said it “took steps on the findings”.

“This raises the issue of whether facial recognition only becomes useful if users accept discrimination in race and gender. Convenience is a weak argument for disregarding basic freedoms.”

Known Issue

Official papers reveal that this bias has been known about for over twelve months. Furthermore, police forces argued to overturn an initial decision that was intended to mitigate the problem.

Police bosses were informed of the algorithmic discrimination in late 2024. The government-ordered laboratory study concluded the system was had a higher probability to suggest incorrect matches for images depicting women, Black people, and those under 40 years old.

A Reversed Decision

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

However, this decision was reversed the next month after forces complained that the modified technology was producing fewer “useful lines of inquiry”. Internal records indicate the stricter setting reduced 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 currently used, the recent NPL study discovered the system could produce false positives for Black women almost 100 times more often than for Caucasian women at specific configurations.

The ministry stated on these findings: “The testing found 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 brief increase to the system's confidence threshold, the police records state: “The change significantly reduces the effect of bias across protected characteristics of ethnicity, age and gender but had a substantially detrimental effect on operational effectiveness”. The papers further note that forces argued that “a previously useful tool now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has opened a two-and-a-half-month consultation on its plans to widen the use of biometric scanning systems. Policing minister Sarah Jones has described the technology as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the independent scrutiny and oversight board for the national policing equality strategy, commented: “We observed very little discussion through equality strategy sessions of the technology deployment despite obvious cross-over with the strategy's goals.

“These revelations show once again that the pledges to combat discrimination policing has undertaken through the race action plan are not being translated into broader operations. Independent assessments have warned that innovative tools are being rolled out in a context where ethnic inequalities, inadequate oversight and poor data collection continue to exist.

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

Official Statement

A government representative stated: “The Home Office takes the conclusions of the report seriously and we have implemented changes. A new algorithm has been externally evaluated and acquired, which has no statistically significant bias. It will be tested in the coming months and will be subject to evaluation.

“Our priority is protecting the public. This gamechanging technology will support police to apprehend and prosecute offenders. There is officer review in each stage of the process and no further action would be pursued without trained officers carefully reviewing the results.”