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92% false positive rate for police facial recognition system
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"A police force has defended its use of facial recognition technology after it was revealed that more than 2,000 people in Cardiff during the 2017 Champions League final were wrongly identified as potential criminals.

South Wales police began trialling the technology in June last year in an attempt to catch more criminals. The cameras scan faces in a crowd and compare them against a database of custody images.

As 170,000 people arrived in the Welsh capital for the football match between Real Madrid and Juventus, 2,470 potential matches were identified.

However, according to data on the force’s website, 92% (2,297) of those were found to be “false positives”.

South Wales police admitted that “no facial recognition system is 100% accurate”, but said the technology had led to more than 450 arrests since its introduction. It also said no one had been arrested after an incorrect match.

A spokesman for the force said: “Over 2,000 positive matches have been made using our ‘identify’ facial recognition technology, with over 450 arrests."

See: Welsh police wrongly identify thousands as potential criminals (The Guardian, link)

And: statement from South Wales Police regarding the use of facial recognition technology: 2,000 positive matches reached with our ‘Identify’ facial recognition technology in past 9 months with over 450 arrests (link):

"Successful convictions so far include 6 years in prison for robbery and 4.5 years imprisonment for burglary.

Of course no facial recognition system is 100% accurate under all conditions. Technical issues are normal to all face recognition systems which means false positives will continue to be a common problem for the foreseeable future. However since we introduced the facial recognition technology no individual has been arrested where a false positive alert has led to an intervention and no members of the public have complained.

AFR ‘Identity’ allows officers to load images of persons of interest and compare them against our 500,000 custody images to see if there is a possible match on identification.
AFR ‘Locate’ is a real time solution which utilises live feeds from CCTV typed cameras based either at specific, fixed locations or cameras secured to the top of one of our vehicle fleet to locate persons on prescribed watch lists."

The true and false positive recognition rate appears to vary widely between different events, judging by statistics published by South Wales Police regarding its use of the technology between June 2017 and March 2018: Facial Recognition Technology - South Wales Police: Story so far (pdf)



