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Police forces across the UK successfully lobbied to use a facial recognition system known to be discriminatory against women, young people, and members of ethnic minority groups, following complaints that a more accurate version generated a reduced number of potential suspects.

The Technology in Practice

British police use the police national database (PND) to conduct searches using historical face recognition. This process entails matching a reference photograph of a person of interest against a database of more than 19 million custody photos to find possible hits.

Admitted Bias

The UK interior ministry admitted last week that the system was biased. This acknowledgment followed a review by the government's National Physical Laboratory found it incorrectly matched people of Black and Asian heritage and females at much greater frequency than Caucasian males. The Home Office stated 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 disregarding 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 earlier ruling that was intended to address the problem.

Police bosses were informed of the system's bias in September 2024. The Home Office-commissioned NPL review concluded the system was had a higher probability to suggest false positives for images depicting females, Black people, and those aged 40 and under.

A Reversed Decision

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

However, this directive was reversed the next month following complaints from police that the modified technology was producing fewer “investigative leads”. NPCC documents show the stricter setting reduced the proportion of searches that yielded potential matches from 56% to a mere 14%.

Severe Disparities

Although the authorities declined to specify what setting is now in operation, the recent independent review found the system could generate incorrect matches for Black women almost 100 times more frequently than for Caucasian women at certain settings.

The ministry commented on these findings: “The testing found that in a limited set of circumstances the algorithm is more likely to wrongly flag some demographic groups in its search results.”

Balancing Utility and Fairness

Describing the effect of the temporary raise to the system's accuracy setting, the NPCC documents note: “The change significantly reduces the effect of bias across legally safeguarded attributes of ethnicity, age and gender but had a significant negative impact on police efficiency”. The documents further note that forces complained that “a previously useful tool returned results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a two-and-a-half-month consultation on its proposals to widen the use of facial recognition technology. The minister for police the relevant minister has described the technology as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the independent scrutiny and oversight board for the police race action plan, said: “We observed very little consideration in equality strategy sessions 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 equality initiative are not being translated into wider practice. Independent assessments have cautioned that innovative tools are being implemented in a landscape where ethnic inequalities, weak scrutiny and faulty information gathering already persist.

“All deployment of this technology must adhere to strict national standards, be independently scrutinised, and demonstrate it reduces rather than compounds ethnic bias.”

Home Office Response

A Home Office spokesperson said: “The Home Office treat the conclusions of the study with utmost gravity and we have already taken action. 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 subject to evaluation.

“The foremost aim 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 process and no arrest or charge would be pursued without trained officers carefully reviewing the output.”