Retrospective searches are widely seen as less controversial, and less difficult to get right, than live facial recognition, which is used in real time to find suspects. Police chiefs still treat facial recognition as the next big leap in crime fighting. Sceptics call it the next huge threat to civil liberties.
His Majesty’s Inspectorate of Constabulary published the findings on Wednesday. The inspection covers only retrospective facial recognition, in which forces search images after an event rather than scanning people in real time.
Police officers risk arresting innocent people, especially from ethnic minorities, if they treat inaccurate facial recognition data as evidence, an official report has found.
Inspectors found that some officers acted on potential matches from those searches without making enough checks. In a small number of cases, officers relied too heavily on the results, and that led to inappropriate investigative action.
“Some investigators didn’t know that RFR results were intelligence rather than evidence and required further enquiries before officers took enforcement action,” the report said.
The report said bias in the algorithm remains. The system is more likely to wrongly flag people from ethnic minorities as suspects. Settings that make misidentification of women and of Asian and black people more likely were also cited in criticism of how the tool is used.
Inspectors found a further threat to public confidence: custody images that should have been deleted were kept. Those failings reduced the system’s ability to return reliable matches.
Critics said police should not be allowed to keep searching against unlawfully held custody images with so few safeguards. The inspection itself did not put a figure on how many such images remain on file.
Although the technology can help fight crime, the report found it is beset by errors and biases. Operators do not always realise they must make further inquiries to verify what the system returns.
“This creates a risk that people could be incorrectly identified or arrested, which could undermine public confidence in the technology,” the report said. “More needs to be done to reduce the risks of people being wrongly arrested.”.
The law has not kept pace. “Inspectors found that legislation hasn’t kept up with changes in facial recognition technology and there is no comprehensive statutory framework governing this technology’s use,” the report said.
That gap, it said, makes it more difficult for forces to understand the lawful basis for retrospective facial recognition and what safeguards are needed to protect the public.
“A clearer statutory framework, stronger national standards and improved governance and oversight arrangements are essential to maintaining public confidence,” the report said.
The inspection’s warning is narrower and more immediate: without stronger checks, a flawed match can send officers after the wrong person, and the people most exposed are those the algorithm is already more likely to misidentify.