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Police forces across the United Kingdom effectively campaigned to deploy a face scanning system known to be biased against females, youths, and individuals from minority ethnic backgrounds, after complaining that a more accurate version generated fewer potential suspects.

How the System Works

British police utilize the police national database (PND) to carry out retrospective facial recognition searches. This procedure entails matching a reference photograph of a suspect against a repository of over 19 million custody photos to identify potential matches.

Admitted Bias

The Home Office conceded last week that the system was biased. This admission followed a review by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and females at significantly higher rates than Caucasian males. The ministry stated it “had acted on the findings”.

“This raises the question of whether this technology only becomes useful if users tolerate discrimination in race and sex. Convenience is a weak argument for overriding fundamental rights.”

Known Issue

Official papers reveal that this discriminatory flaw has been recognized for more than a year. Furthermore, police forces lobbied to reverse an earlier ruling that was intended to address the problem.

Police bosses were notified of the system's bias in late 2024. The Home Office-commissioned NPL review found the system was had a higher probability to produce incorrect matches for photos of women, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) ordered that the accuracy setting required for possible hits be increased to a point where the disparity was greatly diminished.

However, this decision was overturned the next month after forces complained that the adjusted system was producing fewer “useful lines of inquiry”. NPCC documents show the higher threshold reduced the proportion of queries that yielded possible identifications from over half to a just under 15%.

Severe Disparities

Although the authorities declined to specify what setting is now in operation, the latest NPL study found the system could produce false positives for Black women almost 100 times more often than for Caucasian women at certain settings.

The ministry commented on these findings: “Our evaluation identified that in a limited set of circumstances the algorithm is more likely to incorrectly include some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Outlining 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 legally safeguarded attributes of ethnicity, generation and sex but had a substantially detrimental effect on police efficiency”. The papers further note that police units argued that “a once effective tactic now delivered outcomes of questionable value”.

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 the relevant minister has labeled the technology as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the independent scrutiny and oversight board for the national policing equality strategy, commented: “We observed very little discussion in race action plan meetings of the technology deployment even with obvious cross-over with the strategy's goals.

“These revelations show once again that the anti-racism commitments the police has made via the race action plan are failing to be integrated into wider practice. Our reports have cautioned that innovative tools are being implemented in a landscape where racial disparities, inadequate oversight and poor data collection already persist.

“All deployment of facial recognition must meet strict national standards, be independently scrutinised, and prove it diminishes rather than exacerbates racial disparity.”

Home Office Response

A Home Office spokesperson said: “We takes the findings of the report seriously and we have already taken action. A updated software has been externally evaluated and acquired, which has no statistically significant bias. It will be trialled early next year and will be subject to evaluation.

“The foremost aim is ensuring public safety. This revolutionary tool will support police to apprehend and prosecute offenders. There is human involvement in each stage of the process and no further action would be taken without specialist personnel meticulously examining the results.”