British Police Forces Lobbied to Employ Biased Face Scanning Technology

Law enforcement agencies across the United Kingdom effectively campaigned to use a face scanning system acknowledged as biased against women, youths, and individuals from minority ethnic backgrounds, after complaining that a less biased version generated fewer investigative leads.

The Technology in Practice

British police utilize the police national database (PND) to conduct retrospective facial recognition searches. This process involves matching a “probe image” of a person of interest against a repository of over 19 million custody photos to identify possible hits.

Admitted Bias

The Home Office conceded last week that the technology was biased. This acknowledgment came after a review by the National Physical Laboratory (NPL) determined it incorrectly matched Black and Asian people and women at significantly higher rates than Caucasian males. The Home Office stated it “took steps on the findings”.

“This raises the question of whether this technology only becomes effective if users accept discrimination in race and gender. Convenience is a poor argument for overriding basic freedoms.”

Long-Standing Problem

Official papers reveal that this bias has been known about for over twelve months. Furthermore, law enforcement lobbied to reverse an earlier ruling that was intended to address the problem.

Police bosses were informed of the algorithmic discrimination in late 2024. The Home Office-commissioned NPL review found the system was more likely to produce false positives for photos of females, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

In reaction, the National Police Chiefs’ Council (NPCC) ordered that the accuracy setting required for potential matches be raised to a point where the disparity was greatly diminished.

However, this directive was overturned the next month following complaints from police that the adjusted system was producing fewer “investigative leads”. NPCC documents indicate the stricter setting reduced the proportion of queries that yielded possible identifications from over half to a just 14%.

Severe Disparities

Although the authorities declined to specify what threshold is now in operation, the recent independent review discovered the system could produce incorrect matches for Black women nearly a hundred times more frequently than for white women at specific configurations.

The ministry commented on these results: “The testing identified that in a specific scenarios the algorithm is more likely to wrongly flag some population segments 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 legally safeguarded attributes of race, generation and gender but had a significant negative impact on operational effectiveness”. The documents further note that forces complained that “a once effective tactic returned outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has launched a two-and-a-half-month public review on its plans to expand the use of biometric scanning systems. The minister for police Sarah Jones has described the tool as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

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

“This disclosure demonstrate yet again that the anti-racism commitments policing has made via the equality initiative are failing to be integrated into wider practice. Our reports have warned that innovative tools are being rolled out in a context where ethnic inequalities, weak scrutiny and poor data collection continue to exist.

“Any use of facial recognition must meet rigorous official guidelines, be subject to external review, and prove it reduces rather than exacerbates racial disparity.”

Home Office Response

A government representative stated: “The Home Office treat the findings of the report seriously and we have already taken action. A updated software has been externally evaluated and procured, which has no statistically significant bias. It will be tested in the coming months and will be undergo evaluation.

“The foremost aim is protecting the public. This gamechanging technology will assist police to put criminals and rapists behind bars. There is human involvement in every step of the procedure and no further action would be taken without trained officers carefully reviewing the results.”