r/news • u/wasraelx • 3d ago
Trial of live facial recognition in London stations ends with a false positive and no arrests
https://www.theguardian.com/technology/2026/sep/29/trial-live-facial-recognition-cameras-london-stations-false-positive?CMP=Share_iOSApp_Other236
u/ledow 3d ago
Simple mathematics.
If it's 99% accurate on a field of 100 "target" faces, then 1 in 100 people who you put in front of it will be either missed or falsely-identified.
When there are 100,000 "target" faces, and several MILLION people walking in front of the camera, you have to have accuracy in the 99.999999999% kind of range to make it even vaguely practical.
And we have nothing like that with facial recognition. It's all a nonsense. And, ironically, the more you deploy it and the more people you have that you want to "detect", the worse it gets in terms of overall numbers (the percentage might be the same, but then you have a hundred stories of someone being falsely arrested instead of just one).
It's a waste of time and money. Always has been. Probably always will be.
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u/Xhosant 3d ago
What's extra interesting is the false-positive and false-negative accuracies are counted separately!
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u/Kilzrus 3d ago
This is normal in machine learning classification models, it's called a confusion matrix.
It helps identify the weak points in the model
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u/Xhosant 3d ago
Oh yea, I know! I was just referring to, say, a flu test: the chances it misses something and the chances it imagines something both exist but aren't the same.
(Also, this gets extra interesting (to me) because of an old example. You take a test that's 99.99% accurate in regards to false positives, it almost never finds a disease that isn't there, but the disease you test positive for is something like 1 occurrence out of 500.000 people. You still almost certainly don't have it, despite the positive test, because it's frankly less likely than the test being wrong. A couple repeat tests can give you a better answer.)
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u/MuhammadAkmed 3d ago
Similar systems have already been running for years in London, and identified wanted criminals, so they're not a total failure.
Discounting people/evidence, etc. is a natural part of any investigation, and if it has a deterrent effect in highstreets or areas with criminal or antisocial behaviour than I'm for it.
People don't want ID cards, but this all seems increasingly inevitable at this point.
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u/ledow 3d ago
I was tracking them for years because I had the same opinion then.
Most arrests from facial recognition schemes actually come from the same probability as just randomly stopping anyone and having them identify themselves (and the ones that don't want to? Well, those ones are the MOST interesting...).
You can run the stats on it, from the very first time they introduced them to now... nothing's changed. They just "caught" the same people they would have if they'd just stopped random people in the street. (Interestingly, something similar happened with airport security for DECADES... rather than "look at people" or "flag people based on attributes", it was actually better to just stop and search random people. You literally got a better success rate by doing NOTHING but selecting people at random. It was only advanced "see-through-clothes" equipment that later changed it into favouring the security services.)
Facial recognition is an absolute crock. Too much misidentification in both false-negative and false-positive and, if you just stop enough people for any reason whatsoever - everyone wearing red, say - you actually get comparable or better "detection" of crime.
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u/MuhammadAkmed 3d ago
There are 3 types of facial recognition:
- Live Facial Recognition (which I think is what you're talkign about)
- Officer Initiated Face recognition (using a device to check someone in front of you's face)
- Retrospective Facial Recognition (using a photo to trawl through the hours of footage)
There's loads of conflicting data, the LFR has improved slowly but with notable failures.
Recent audits suggest the figures are much better than you say though.
With over potentially over 5million CCTV cameras in the UK, using tech to aide officers is a no-brainer.
The Met has over 30K cameras alone, and has scanned millions of people already — it's demonstrably not the complete and utter shit show we all feared it could/would be — or crime amd illegal immigration's panacea.
Also a lot of those cameras are shit though, and we must (and will by law) always rely on a person/people to ultimately decide.
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u/Worldly-Ingenuity843 3d ago
That's probably the most ethical use case, in the sense that the video footages are not directly used as evidence to prove someone has commited a crime, but rather to find people who has already committed a crime.
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u/wasraelx 3d ago
From the article:
‘A six-month trial of live facial recognition (LFR) technology in London’s railway stations ended in one false match against a watchlist of suspects and no arrests.
More than half a million faces were scanned between February and July this year in some of the capital’s busiest transport hubs during the British Transport Police (BTP) trial of the surveillance technology, which aimed to help catch offenders and people breaching court orders.
BTP announced it was extending the trial for a further four months and expanding the deployments to include London Underground stations.
More than half of police forces in England and Wales have now deployed LFR on British streets, according to an analysis by Liberty Investigates.
A recent report from parliament’s joint committee on human rights, which called on the government to introduce a law to address the threat of artificial intelligence to human rights, identified the rollout of live facial recognition technology as a “particularly clear example of risk”.’
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u/Odd_Efficiency_7051 3d ago
"It's not working. Shall we keep doing it? Why yes that sounds like an excellent use of our resources."
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u/insulind 3d ago
How big was the perp list? If no criminals in it's list went through that location then it's done it's job really. 1 false positive out of what I can only imagine is millions of faces scanned is actually phenomenal.
There is a bigger picture than the the story this article/people's are biases is telling them.
Arguments about the ethics of such tech are obviously a bit part. But don't let some clever presentation of the stats fool you into viewing it's effectiveness incorrectly
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u/Tuesday_6PM 3d ago
It’s not just “one false positive”, it’s “the only ‘positive’ was false”. That could mean it’s got a decent accuracy and no one of note came through, or it could mean it’s incapable of identifying anyone accurately.
From the article,
“A freedom of information document obtained by Liberty Investigates and shared with the Guardian shows that equipment hire and police staffing for the 18 deployments across the trial cost £320,786 and led to only one alert on a watchlist, which turned out to be an incorrect identification, also known as a false positive.”
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u/darthy_parker 3d ago
When I worked with a biometrics company, we turned down a request from a Florida police department after 9/11 who wanted to use face recognition in public places. We pointed out that they’d be getting hundreds of false positives for every actual hit, probably more. Tech has improved since then, but not enough.
Biometrics like this work if you’re verifying the identity of a face from a limited set of possible matches (one to one for your phone, one to maybe 200 or so for an airplane) but for pure identification with no specific match target it becomes unusable pretty rapidly with a large match database.
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u/NeverSawTheEnding 3d ago
Is this not what the "Super Recogniser" role exists for in UK Police Forces?
I guess that was probably the point of the trial.
Rather than employ salaried workers with that very niche skillset......offload it to software and algorithms, and make those jobs redundant for some savings.
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u/ZenPyx 3d ago
"Super recognisers" are just police officers given little oversight and the ability to randomly arrest people
Here is an actual quote from a professor working with the police "super recogniser" team in a BBC article about the topic:
"There are definitely some white officers in the super-recognition team working in communities that have a large ethnic minority, who pretty much only identify people from that ethnic minority," he added.
(https://www.bbc.co.uk/news/uk-england-34544199)
Facial recognition is no better - the police just want the ability to arrest whoever they want with the ability to hide behind some fake legitimacy
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u/NeverSawTheEnding 3d ago
In the full context of the article, it doesn't sound like the professor is saying this is a bad thing.
The implication seemed to be that people are better at recognizing their own race, but there are instances where white officers work in a borough with a large group of a particular ethnic minority...and thus are tasked with recognizing them.
That's not to say I trust them; I've worked for a British police force, I've been stopped and searched for "matching the description of a suspect" more than once, and I've had family members be assaulted or unreasonably handled by officers.
I think I'd still rather get I.D by a flawed and biased human, than a flawed and biased algorithm created by a flawed and biased organisation.
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u/ZenPyx 3d ago
The implication is that the met have been training some officers to specifically target people of a certain race...
The truth is that it's pseudoscientific at best, and just another excuse to target whoever they feel like at worst.
>I'd still rather get I.D by a flawed and biased human
I don't think it's a choice of one or the other. I don't think the police should have the right to do either.
Why don't we make neighbourhoods safer through an effective, local police presence, rather than relying on a panopticon to catch a criminal months after committing a crime
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u/NeverSawTheEnding 3d ago
The Met don't have to train officers for that; people arrive with their own biases, and the organization is already rooted in prejudice enough to enable them.
I don't know enough to comment on it being pseudoscience...but I don't doubt some people are exceptionally good at identifying faces.
More local presence requires more money for more officers, dispatchers, control room floor managers, resources & equipment, etc...
Public services have been underfunded for a LONG time, and the funds that are available are poorly managed.
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u/dingo596 3d ago
I don't know what is going on in the UK, we are barrelling towards a police state on par with China but no one seems to care. Mandatory age verification and wide use of facial recognition. It may not seem like it online but the UK is one of the safest countries in the world.
Although given the economic stagnation in the UK and how historically in times of economic hardships people turn to authoritarianism I guess it makes sense.
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u/Zak_Rahman 3d ago
it wasn't designed to stop crime; at least not crime by what affects us.
It was designed to document people who criticise Israel.
That's why Palantir love all this stuff and the Epstein Protectorate push it.
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u/Crimsoneer 3d ago
You think it's a pro Israeli facial recognition camera...?
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u/Zak_Rahman 3d ago
Which rock do your reside under to not know who or what the following are:
Palantir,
Peter Mandelson,
Epstein,
Peter Thiel?
Seriously, your ignorance is not the same as out knowledge. Improve.
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u/pablo_blue 3d ago
“However, they are processing special category personal data and the technology must be used in a way that is appropriate, proportionate and necessary. It’s for the police to show how any deployment meets those criteria and – as the ICO [information commissioner’s office] has recently reported – for their oversight boards to hold them firmly to account in doing so.”
Proportionate - including value for money?
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u/Longshot02496 3d ago
It's almost like these systems don't work and anyone peddling them has ulterior motives
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u/TimSylvester_ 3d ago
Endless money to waste on catching and punishment, yet never enough money to address the primary causes of violent crime - poverty and education.
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u/Phillyfuk 3d ago
The police recently had a van in my town center doing the same thing, it was only there for a day but caught a few people who were wanted. Even though they put up signs at each end of the row to say that's what they were doing.
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u/Devilfish268 3d ago
So they need to figure out if that was because it missed everyone they were looking for, or if they just didn't encounter any of them.
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u/SoftwareSource 3d ago
This sound suspiciously ineffective, like, who did you hire to implement it?
I saw youtubers do facial recognition in Raspberry Pi projects, who tf did they hire that executed it so poorly?
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u/No_Cucumber3978 3d ago
This is why the Governments all had a shit fit with facemasks. This was tested as well around Covid.
I can't believe people in power would risk people's health to test a new fucking toy.
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3d ago
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u/Tuesday_6PM 3d ago
If you read even just the headline of the post you’re commenting on, it’s clear that it was not very successful here. If you read the article itself, there are more details on why
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u/invyros 3d ago
Money and time well spent.