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Law enforcement agencies across the UK successfully lobbied to use a facial recognition system known to be biased against females, youths, and members of ethnic minority groups, after complaining that a less biased version produced a reduced number of potential suspects.

How the System Works

British police utilize the national police database to conduct searches using historical face recognition. This process involves matching a “probe image” of a person of interest against a database of more than 19 million custody photos to identify potential matches.

Acknowledged Discrimination

The UK interior ministry conceded last week that the system was flawed. This admission followed a study by the National Physical Laboratory (NPL) found it misidentified Black and Asian people and females at much greater frequency than Caucasian males. The Home Office said it “had acted on the findings”.

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

Long-Standing Problem

Internal documents show that this discriminatory flaw has been recognized for over twelve months. Furthermore, law enforcement lobbied to reverse an initial decision that was designed to mitigate the problem.

Police bosses were informed of the algorithmic discrimination in September 2024. The government-ordered laboratory study found the system was had a higher probability to produce incorrect matches for photos of women, 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 raised to a point where the disparity was greatly diminished.

However, this directive was overturned the following month following complaints from police that the adjusted system was generating fewer “investigative leads”. NPCC documents show the higher threshold reduced the number of queries that yielded possible identifications from 56% to a mere 14%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what threshold is now in operation, the recent NPL study found the system could produce false positives for women of Black heritage almost 100 times more often than for Caucasian women at certain settings.

The Home Office commented on these findings: “Our evaluation found that in a limited set of circumstances the software is more likely to incorrectly include some demographic groups 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 impact of bias across legally safeguarded attributes of ethnicity, age and gender but had a substantially detrimental effect on police efficiency”. The papers further note that police units complained that “a once effective tactic returned outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the government has launched a ten-week public review on its proposals to expand the use of biometric scanning systems. The minister for police Sarah Jones has described the tool as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the advisory panel for the national policing equality strategy, commented: “There was very little consideration in race action plan meetings of the facial recognition rollout even with clear relevance with the strategy's goals.

“This disclosure demonstrate yet again that the anti-racism commitments policing has undertaken through the race action plan are not being translated into wider practice. Our reports have cautioned that new technologies are being rolled out in a landscape where ethnic inequalities, inadequate oversight and poor data collection continue to exist.

“Any use of facial recognition must adhere to rigorous official guidelines, be independently scrutinised, and prove it diminishes rather than exacerbates racial disparity.”

Official Statement

A Home Office spokesperson stated: “We takes the findings of the report seriously and we have already taken action. A new algorithm has been externally evaluated and acquired, which has no statistically significant bias. It will be trialled early next year and will be undergo evaluation.

“Our priority is protecting the public. This revolutionary tool will support officers to put criminals and rapists behind bars. There is human involvement in every step of the procedure and no further action would be taken without specialist personnel carefully reviewing the results.”