British Police Forces Lobbied to Employ Biased Face Scanning Systems

Law enforcement agencies across the United Kingdom successfully lobbied to deploy a facial recognition system known to be biased against women, youths, and individuals from minority ethnic backgrounds, after complaining that a less biased version generated a reduced number of potential suspects.

How the System Works

British police use the police national database (PND) to carry out searches using historical face recognition. This procedure entails comparing a “probe image” of a suspect against a repository of more than 19 million custody photos to find possible hits.

Acknowledged Discrimination

The Home Office admitted last week that the system was biased. This admission came after a review by the government's National Physical Laboratory found it misidentified Black and Asian people and females at significantly higher rates than Caucasian males. The Home Office stated it “had acted on the findings”.

“It prompts the issue of whether facial recognition only becomes effective if users accept biases in race and sex. Convenience is a poor argument for overriding fundamental rights.”

Known Issue

Internal documents reveal that this bias has been known about for over twelve months. Furthermore, police forces lobbied to reverse an initial decision that was intended to address the problem.

Senior officers were informed of the algorithmic discrimination in late 2024. The government-ordered NPL review found the system was had a higher probability to suggest false positives for images depicting females, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) ordered that the accuracy setting required for possible hits be increased to a level where the disparity was greatly diminished.

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 indicate the stricter setting cut the number of searches resulting in potential matches from 56% to a mere 14%.

Severe Disparities

Although the Home Office and NPCC declined to specify what threshold is currently used, the latest independent review discovered the system could generate incorrect matches for women of Black heritage almost 100 times more frequently than for Caucasian women at certain settings.

The ministry stated on these results: “The testing found that in a limited set of circumstances the algorithm is has a greater tendency to incorrectly include some population segments in its search results.”

Balancing Utility and Fairness

Describing the impact of the temporary raise to the system's confidence threshold, the NPCC documents state: “This adjustment significantly reduces the impact of discrimination across legally safeguarded attributes of ethnicity, generation and gender but had a substantially detrimental effect on police efficiency”. The documents further note that forces argued that “a once effective tactic returned outcomes 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 described the tool as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the police race action plan, said: “There was very little discussion through equality strategy sessions of the facial recognition rollout even with clear relevance with the strategy's goals.

“This disclosure show once again that the pledges to combat discrimination policing has undertaken through the race action plan are failing to be integrated into wider practice. 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.

“All deployment of facial recognition must meet strict national standards, be subject to external review, and prove it diminishes rather than exacerbates ethnic bias.”

Official Statement

A government representative said: “The Home Office takes the findings of the report seriously and we have implemented changes. A updated software has been independently tested and procured, which has no statistically significant bias. It will be tested in the coming months and will be undergo further assessment.

“Our priority 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 process and no further action would be taken without specialist personnel meticulously examining the results.”