British Police Forces Campaign to Use Biased Face Scanning Systems

Police forces across the UK effectively campaigned to use a face scanning system acknowledged as biased against women, youths, and members of minority ethnic backgrounds, following complaints that a less biased version generated fewer investigative leads.

The Technology in Practice

UK forces use the police national database (PND) to conduct retrospective facial recognition searches. This procedure involves comparing a reference photograph of a person of interest against a repository of more than 19 million custody photos to identify potential matches.

Acknowledged Discrimination

The Home Office admitted last week that the technology was biased. This admission came after a review by the government's National Physical Laboratory found it incorrectly matched people of Black and Asian heritage and women at much greater frequency than Caucasian males. The ministry stated it “took steps on the findings”.

“This raises the issue of whether this technology only becomes effective if users accept discrimination in ethnicity and gender. Operational ease is a weak argument for disregarding basic freedoms.”

Long-Standing Problem

Internal documents reveal that this bias has been recognized for over twelve months. Furthermore, police forces argued to overturn an initial decision that was designed to mitigate the problem.

Senior officers were notified of the algorithmic discrimination in September 2024. The government-ordered NPL review found the system was had a higher probability to produce incorrect matches for images depicting females, Black people, and those aged 40 and under.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for potential matches be increased to a point where the bias was greatly diminished.

However, this directive was reversed the following month after forces complained that the modified technology was producing fewer “useful lines of inquiry”. NPCC documents indicate the higher threshold reduced the number of searches that yielded potential matches from over half to a just under 15%.

Profound Inequalities

Although the Home Office and NPCC refused to say what setting is currently used, the recent NPL study discovered the system could produce incorrect matches for women of Black heritage almost 100 times more often than for white women at certain settings.

The Home Office stated on these results: “Our evaluation found that in a limited set of circumstances the algorithm is has a greater tendency to incorrectly include some demographic groups in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the brief increase to the system's accuracy setting, the NPCC documents note: “This adjustment greatly lessens the effect of discrimination across protected characteristics of race, generation and sex but had a substantially detrimental effect on police efficiency”. The papers add that forces complained that “a once effective tactic returned outcomes of questionable value”.

Wider Implementation Proposals

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

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the police race action plan, commented: “We observed scant consideration through race action plan meetings of the technology deployment even with clear relevance with the plan’s concerns.

“These revelations show once again that the pledges to combat discrimination policing has made through the race action plan are failing to be integrated into broader operations. Our reports have cautioned 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 exacerbates racial disparity.”

Official Statement

A government representative stated: “We treat the conclusions of the study seriously and we have implemented changes. A new algorithm has been externally evaluated and procured, which has no statistically significant bias. It will be trialled in the coming months and will be undergo evaluation.

“Our priority is protecting the public. This gamechanging technology will assist officers to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no further action would be taken without specialist personnel meticulously examining the output.”