British Police Forces Campaign to Use Biased Face Scanning Systems

Law enforcement agencies across the UK effectively campaigned to deploy a facial recognition system known to be discriminatory against women, young people, and members of minority ethnic backgrounds, following complaints that a more accurate version generated fewer potential suspects.

The Technology in Practice

British police use the national police database to carry out searches using historical face recognition. This procedure involves comparing a “probe image” of a person of interest against a repository of over 19 million mugshots to identify potential matches.

Admitted Bias

The UK interior ministry conceded last week that the system was flawed. This admission followed a study by the National Physical Laboratory (NPL) determined it incorrectly matched Black and Asian people and females at much greater frequency than Caucasian males. The ministry said it “took steps on the findings”.

“It prompts the issue of whether this technology only becomes useful if users accept biases in ethnicity and gender. Operational ease is a weak argument for overriding basic freedoms.”

Long-Standing Problem

Official papers show that this bias has been recognized for more than a year. Furthermore, police forces argued to overturn an initial decision that was intended to mitigate the problem.

Senior officers were notified of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review found the system was had a higher probability to suggest false positives for photos of women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In response, the national police leadership body ordered that the confidence threshold required for possible hits be raised to a point where the disparity was significantly reduced.

However, this directive was reversed the next month following complaints from police that the adjusted system was producing fewer “investigative leads”. NPCC documents indicate the stricter setting cut the proportion of searches that yielded possible identifications from 56% to a mere under 15%.

Severe Disparities

Although the Home Office and NPCC declined to specify what setting is now in operation, the latest independent review found the system could generate false positives for women of Black heritage almost 100 times more often than for white women at specific configurations.

The ministry commented on these findings: “The testing found that in a specific scenarios the algorithm is has a greater tendency to incorrectly include some population segments in its search results.”

Operational Effectiveness vs. Bias

Outlining the impact of the temporary raise to the system's confidence threshold, the police records note: “This adjustment significantly reduces the effect of discrimination across protected characteristics of ethnicity, generation and gender but had a substantially detrimental effect on operational effectiveness”. The papers further note that police units complained that “a previously useful tool now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has opened a ten-week consultation on its plans to widen the use of facial recognition technology. Policing minister the relevant minister has described the technology as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

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

“These revelations show once again that the pledges to combat discrimination policing has made through the equality initiative are not being translated into wider practice. Our reports have cautioned that innovative tools are being implemented in a landscape where ethnic inequalities, inadequate oversight and poor data collection already persist.

“All deployment of facial recognition must adhere to rigorous official guidelines, be independently scrutinised, and prove it diminishes rather than compounds ethnic bias.”

Home Office Response

A Home Office spokesperson said: “The Home Office takes the findings of the study seriously and we have implemented changes. A new algorithm has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be tested early next year and will be undergo evaluation.

“Our priority is ensuring public safety. This revolutionary tool will assist police to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no further action would be taken without trained officers meticulously examining the results.”