Ban UK police use of facial-recognition, House of Lords told

UK police continue to deploy facial-recognition technology disproportionately with no clear legal basis and highly questionable efficacy, according to expert witnesses at a House of Lords inquiry.

In evidence given to the Lords Home Affairs and Justice Committee about the use of advanced algorithmic tools by law enforcement, experts called into question the proportionality and efficacy of how facial-recognition technology has been deployed by the Metropolitan Police Service (MPS) and South Wales Police (SWP).

Silkie Carlo, director of civil liberties campaign group Big Brother Watch, said that in five years the MPS had only achieved 11 positive matches using live facial-recognition (LFR) technology, following trial deployments which began in 2016 at the Notting Hill Carnival and ended in February 2019 with two deployments in Romford, before fully operational use began in January 2020.

“In that time, they have scanned hundreds of thousands of people on the streets of London, and created a lot of distrust among communities, particularly by deploying repeatedly at Notting Hill Carnival – I think there’s inevitably a racialised element to that – and by deploying repeatedly in the borough of Newham as well, which is the most diverse borough of London,” she said.

“Not only have they only had 11 true matches, they have generated an awful lot of false positive matches. Their current rate over the entirety of the deployments is 93% false positive matches, so I struggle to see a world in which that could be classed as anything near proportionate.”

On the MPS’ LFR trials, Karen Yeung – an Interdisciplinary Professorial Fellow in Law, Ethics and Informatics at Birmingham Law School – described the force’s scientific methodology as “very unrigorous”, noting that because procedures were tweaked every time a trial was conducted, “we do not have a stable and rigorous set of data on the basis of these experiments”.

She added: “In those 11 trials, 500,000 faces were scanned to produce nine to 10 arrests, and many of those were individuals who were wanted for very trivial offences. All of this means the real-time location tracking of many, many hundreds of thousands of British people going about their lawful business, not bothering anyone.

“This is a serious reversal of the presumption that one is entitled to go about their business in a lawful manner, without being disturbed by the state, and I completely support Silkie’s view that this should be subject to very, very stringent regulations, if not an outright ban.”

Yeung further noted that, unlike LFR trials conducted in Germany and France, the MPS tested the technology on real-life suspects.

“In other Western European countries, they have been using volunteers to test the accuracy of this data, and they have a full database of the people passing in front of the cameras – this has not been the case in London, they have been doing operational trials,” she said. 

She added that while the MPS have purported to comply with data protection legislation, the documents that have been published so far “are seriously deficient, in my view, in terms of the extent to which they declared operational purposes, and the question of impact evaluation and proportionality”.

Yeung said that any conclusion the MPS’ LFR experiments were successful is not sustained by the available evidence.