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Police forces across the UK successfully lobbied to use a facial recognition system acknowledged as biased against women, young people, and individuals from ethnic minority groups, after complaining that a more accurate version generated a reduced number of potential suspects.

The Technology in Practice

UK forces utilize the police national database (PND) to conduct searches using historical face recognition. This process involves comparing a “probe image” of a person of interest against a database of more than 19 million custody photos to identify possible hits.

Admitted Bias

The UK interior ministry admitted last week that the technology was flawed. This acknowledgment came after a review by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and females at much greater frequency than Caucasian males. The ministry stated it “had acted on the findings”.

“It prompts the issue of whether facial recognition only becomes effective if users accept discrimination in ethnicity and sex. Convenience is a weak argument for disregarding fundamental rights.”

Long-Standing Problem

Internal documents show that this discriminatory flaw has been known about for over twelve months. Furthermore, law enforcement lobbied to reverse an earlier ruling that was designed to mitigate the problem.

Police bosses were informed of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review found the system was more likely to produce false positives 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) mandated that the confidence threshold required for potential matches be increased to a point where the bias was significantly reduced.

However, this decision was reversed the next month following complaints from police that the modified technology was producing fewer “useful lines of inquiry”. Internal records show the higher threshold reduced the number of searches resulting in potential matches from over half to a just under 15%.

Profound Inequalities

Although the authorities refused to say what setting is now in operation, the latest NPL study discovered the system could generate incorrect matches for Black women nearly a hundred times more frequently than for white women at specific configurations.

The Home Office commented on these results: “The testing identified that in a limited set of circumstances the algorithm is has a greater tendency to incorrectly include some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's accuracy setting, the police records note: “The change significantly reduces the impact of bias across legally safeguarded attributes of race, age and sex but had a significant negative impact on operational effectiveness”. The documents add that police units argued that “a previously useful tool now delivered outcomes of limited benefit”.

Broader Rollout Plans

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

Expert and Oversight Concerns

The chair of a police oversight board, head of the advisory panel for the national policing equality strategy, commented: “We observed scant consideration through equality strategy sessions of the facial recognition rollout despite clear relevance with the plan’s concerns.

“These revelations demonstrate once again that the pledges to combat discrimination the police has undertaken via the race action plan are not being translated into wider practice. Independent assessments have cautioned that new technologies are being implemented in a context where racial disparities, weak scrutiny and faulty information gathering already persist.

“Any use of this technology must adhere to rigorous official guidelines, be subject to external review, and demonstrate it diminishes rather than compounds racial disparity.”

Home Office Response

A government representative stated: “The Home Office treat the conclusions of the study 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 early next year and will be undergo further assessment.

“The foremost aim is protecting the public. This revolutionary tool will support police to put criminals and rapists behind bars. There is officer review in every step of the process and no arrest or charge would be pursued without specialist personnel meticulously examining the output.”