Schneier on Security
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August 17, 2007
On the Ineffectiveness of Security Cameras
Information from San Francisco public housing developments:
The 178 video cameras that keep watch on San Francisco public housing developments have never helped police officers arrest a homicide suspect even though about a quarter of the city's homicides occur on or near public housing property, city officials say.
Nobody monitors the cameras, and the videos are seen only if police specifically request it from San Francisco Housing Authority officials. The cameras have occasionally managed to miss crimes happening in front of them because they were trained in another direction, and footage is particularly grainy at night when most crime occurs, according to police and city officials.
Similar concerns have been raised about the 70 city-owned cameras located at high-crime locations around San Francisco.
Four homicides have occurred in the past 12 months at the intersection of Laguna and Eddy streets -- at the corner of the Plaza East public housing development -- including the daytime killing of a 19-year-old in May. A security camera is trained on that corner but so far has not proven useful in making any arrests, Mirkarimi said.
Both the Housing Authority and city have many security cameras in the area, and it wasn't clear Monday whether the camera in question was purchased by the Housing Authority or city. In any case, the camera hasn't helped make arrests in the crimes, Mirkarimi said.
"They're feeling strongly that they don't work," Mirkarimi said of Western Addition residents' views of the security cameras. "They're just apoplectic why they can't figure out why nothing comes of this."
He added that he thinks the cameras may have "a scarecrow effect" in that they give residents the feeling they are safer when they actually have little impact on crime.
That's not a scarecrow effect. A scarecrow is security theater that works: something that doesn't actually prevent crime, but deters it by scaring off criminals. Mirkarimi is saying that they have the opposite effect; the cameras make victims feel safer than they really are.
Posted on August 17, 2007 at 1:25 PM
• 30 Comments
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Gotta hand it to that Housing Authority. Quite a shock that a governmental agency is performing incompetently.
"footage is particularly grainy at night when most crime occurs"
Er, install some better lighting? Higher quality cameras?
"Nobody monitors the cameras"
Yeah, ya might start there. Geniuses.
Wouldn't better lighting be a cheaper and possibly more effective solution?
Pronouncing security cameras ineffective using this example is like trying to show that legal firearm possesion doesn't deter crime, by putting an unloaded pistol out in the street in front of your house, then getting robbed in your home, and then saying, "See?! Gun ownership doesn't prevent crime!"
Security cameras aren't sentient beings. They're tools to be used as a part of a security system, highly effective in the hands of non-morons.
Scarecrows are effective?
Given how uninterested the crows in my neighbourhood are in real live humans, I'd be surprised if any crows were intimidated by some old clothes on a straw dummy.
"If men had wings and bore black feathers, few of them would be clever enough to be crows." -Rev.Henry Ward Beecher
I don't think the intent of the article is to definitively say "security cameras are ineffective". Rather, I think it illustrates exactly what you say: security cameras are merely tools, and not sentient being. I think often people/businesses/government do not understand that point and simply install security cameras without much concrete thought as to how they might be used to prevent and deter crime.
The solution is obvious: more cameras!
Another analogy would be the fake owls put on roofs to frighten away the pigeons. Within months, the fakes are covered by pigeon droppings.
I suspect ordinary criminals are far smarter than birds.
I'd agree with the scarecrow effect. A stationary scarecrow will eventually become a landing spot for birds. So the farmer may think his crop is safe, when the birds just ignore it.
How does this compares to the UK ‘big brother’ network of cameras? I seem to remember that it was proven useful in a number of high-profile cases. Was that relevant or just statistical noise? What was different?
So the question is: is it a problem with the concept of cameras or is it more of an implementation problem? I think it's a bit of both.
Cameras are only effective as the security program that implemented them. Judging from this statement, "NOBODY MONITORS THE CAMERAS" it sounds like there is NO program at all.
This is the equivalent of using rot 13 to "encrypt" credit card numbers on an anonymous public ftp site and then claiming that encryption doesn't work when the "encrypted" files are "Decrypted".
Its just as easy to screw up physical security as it is to screw up computer security.
"the cameras make victims feel safer than they really are."
This is similar to the fact that nighttime "security lighting" has no effect on crime, and in fact may increase crime.
Very interesting to note that the same problem exists with cameras. Have similar studies been performed? As this is presented, it's merely anecdotal evidence, but clearly worthy of deeper investigation.
There is little evidence that street cameras reduce the overall frequency of crime and there is evidence that it just moves crime to areas without the cameras (but even then the effect is temporary.)
On a very few occasions, the images are useful _after_ the event, which is not much consolation to the victims.
Street cameras are possibly the purest form of "security theatre". Big Brother will protect you if you only surrender a little privacy. But you get neither protection nor much remaining privacy.
@Leandro GFC DUTRA
The UK's network of cameras is useful for catching criminals after the event IF the powers that be can bothered to look through hours of footage. Generally this only happens in the case of more serious crimes. For petty theft - forget it.
I don't know of any studies or figures which have analysed their effectiveness.
Despite what you may read about the UK being covered in security cameras, it isn't and most people don't really care about them anyway.
What's much more high profile in the UK is the use of cameras to catch speeding motorists. These cameras are generally viewed to be:
a. Used mainly to generate revenue - the regulations have changed recently and I can't remember who gets to keep the revenue these days.
b. Ineffective in reducing accident levels - I believe that there is no conclusive evidence either way for this.
There are a few Dutch cities that have security camera networks and these cameras (and the video registrations they made) have been instrumental in solving crimes. What those cities have is a central control room with people watching the screens and a hot line to law enforcement and ambulance services, so that they can direct the emergency response. I have no statistics, only second hand anecdotal evidence; one of the cases is police catching some rapists "in the act".
Do cameras prevent crime? I don't think so. It may be a second order effect from swiping up the petty criminals in the region and moving the pros to other areas. Does a proper camera network help to use police forces more effectively? Yes; I count the cameras as additional eyes that can coordinate the hands. And yes, the recorded video can be used as evidence in court, easing conviction of criminals.
There are some hard questions: do the benefits of a camera system warrant the investment? Does it warrant the invasion of privacy? It would help if camera recordings are erased/overwritten after a few days, only keeping the shots that are needed for prosecution of crimes.
What's the problem in SFO... If nobody is watching the monitors, you can just as well replace the cameras by mock ups.
"Mirkarimi is saying that they have the opposite effect; the cameras make victims feel safer than they really are."
Sounds like the situation with painted cross walks which give pedestrians a false sense of safety. Removing those painted cross walks while still allowing crossing has been shown to make pedestrians safer because they know they have to look out for themselves.
@Government, community, "nobody monitors the cameras":
Duh. It would be prohibitively expensive if every security camera was monitored, and even more so if you intended to have law enforcement in the vicinity so that they could react to an incident fast enough to make a difference.
Most security cameras are intended to scare criminals off because they'll be caught on tape. But that only works if there are procedures in place to review the tapes after an incident, of good enough quality to identify the villain, and with resources available to track down offenders.
The UK network of surveillance cameras has mixed effectiveness.
It is completely useless for solving crimes that do not happen directly in front and good view of them. Most crimes don't. For example, a camera was filming people entering a building. A person was filmed entering the building, with an empty rucksack. 10 minutes later, the person left, with a full rucksack. During this time period, a theft happened from a room (while the occupant was out for a few minutes). The picture of the intruder was printed on a poster with the question whether this person was known to anybody. However, this publication of photo and implied involvement of that person in crime was found to breach law (which it does). Now what use is the camera? None. It will never film crime.
The only benefit of cameras I have experienced is to monitor hotspots in the evenings. In the UK, pubs used to close at 11pm, sending plenty of very drunk, aggressive people on the road. So just the opportunity for a (fist) fight. I have seen very fast police response to fights that were only just starting owing to CCTV.
Making people feel safer isn't necessarily a bad thing. How safe people feel is often not directly related to how safe they are; statistics on violent crime often trend one direction while surveys on how safe people feel trend the other. This is probably in part caused by the "if it bleeds it leads" mentality of the press.
So if putting up some security cameras lets people get on with their lives instead of cowering in fear because the press screamed "DOOOOOOOM", then they serve a valuable public policy purpose. Since the primary objection to them is usually based on government invasion of privacy, not having them actually DOING anything can be a positive thing in that regard.
But yes, the best security cameras in terms of security would be ones that actually recorded good pictures that were available to law enforcement in a timely manner.
"Making people feel safer isn't necessarily a bad thing."
Only if their feeling of insecurity is baseless.
Making people feel safe when they are, in fact, in danger is a bad thing and leads to incautious behavior. In such a case, the **false** sense of security can actually make people less safe and the security theater is counter productive and espousal of its value is counterfactual.
(Look in the URL field)
A picture I took (in South Africa) at a gas station. Why would one possibly need all those CCTV cameras? I think I counted about 25 cameras in total at that station. And it's not even an area with a lot of crime. I think the owner of the gas station simply has too much money and time on his hands ;-)
How about hiring Chinese "gold farmers" to watch the cameras? Maybe just those showing movement and with big incentives for reporting a crime fast enough for police response.
Any competent crime reporter knows about these cameras, and knows who can be bribed or coerced to violate his employment contract by providing a copy of anything exciting. I have seen a local TV station (Boston MA) broadcast the video of a capital crime before the investigating detectives had viewed it.
'This is the equivalent of using rot 13 to "encrypt" credit card numbers'
How do you do rot13 on numbers?
one two three
bar gjb guerr
How wrong you are! You didn't hear any reports of elephants or hyenas committing crimes against humanity in the areas where these cameras were operating did you?
Working as intended.
I would name the Opposite of SCARECROW effect as The FENCE-POLE effect. Part of the fence is installed, and the by-standers think that the fence is complete when it doesn't extend far enough to deter the bull on one side from going around it, (or through it!), and does nothing to slow down the rattlesnakes. Sort of like Jurassic Park with the power turned off.
"apoplectic", Seriously, she accused them of having stroke like symptoms?
I'm pretty sure this is a misprint.
We had cameras that could take photos of you running a red light, there were about three lenses behind armored glass, probably a camera for daylight, one for infrar red and and an exray to see if you have things in your pocket. to see the future of law enforcemnent, go to the movie "minority report"
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