UK Law Enforcement Agencies Lobbied to Use Biased Face Scanning Systems

Police forces across the UK effectively campaigned to use a facial recognition system known to be discriminatory against females, youths, and members of minority ethnic backgrounds, after complaining that a less biased version produced fewer investigative leads.

The Technology in Practice

British police use the national police database to conduct searches using historical face recognition. This procedure involves matching a “probe image” of a suspect against a repository of over 19 million mugshots to find possible hits.

Admitted Bias

The Home Office admitted last week that the system was flawed. This admission 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 Caucasian males. The ministry stated it “had acted on the findings”.

“It prompts the issue of whether this technology only becomes useful if users accept discrimination in race and gender. Convenience is a poor argument for overriding fundamental rights.”

Known Issue

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

Police bosses were informed of the algorithmic discrimination in late 2024. The government-ordered NPL review found the system was more likely to produce incorrect matches for images depicting females, Black people, and those aged 40 and under.

A Policy U-Turn

In response, the National Police Chiefs’ Council (NPCC) ordered that the confidence threshold required for possible hits be increased to a point where the bias was significantly reduced.

However, this decision was overturned the next month following complaints from police that the adjusted system was producing a lower number of “investigative leads”. Internal records show the higher threshold reduced the proportion of searches that yielded possible identifications from over half to a just under 15%.

Severe Disparities

Although the Home Office and NPCC refused to say what threshold is now in operation, the latest independent review found the system could produce incorrect matches for Black women nearly a hundred times more often than for Caucasian women at specific configurations.

The Home Office commented on these results: “Our evaluation identified that in a specific scenarios the software is more likely to incorrectly include some population segments in its match reports.”

Balancing Utility and Fairness

Describing the effect of the brief increase to the system's confidence threshold, the NPCC documents note: “The change significantly reduces the effect of bias across protected characteristics of race, age and gender but had a substantially detrimental effect on operational effectiveness”. The documents add that police units argued that “a previously useful tool now delivered results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a two-and-a-half-month consultation on its plans to widen the use of facial recognition technology. Policing minister Sarah Jones has labeled the tool as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the national policing equality strategy, commented: “We observed scant consideration through equality strategy sessions of the technology deployment despite clear relevance with the strategy's goals.

“This disclosure show yet again that the anti-racism commitments the police has undertaken through the equality initiative are failing to be integrated into broader operations. Our reports have warned that new technologies are being rolled out in a landscape where ethnic inequalities, weak scrutiny and faulty information gathering already persist.

“Any use of this technology must meet strict national standards, be subject to external review, and demonstrate it diminishes rather than exacerbates racial disparity.”

Home Office Response

A government representative said: “We takes the findings of the report with utmost gravity and we have implemented changes. A new algorithm has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be tested early next year and will be subject to further assessment.

“Our priority is protecting the public. This gamechanging technology will assist officers to put criminals and rapists behind bars. There is officer review in every step of the procedure and no further action would be taken without trained officers carefully reviewing the output.”