Surveillance Cameras and Terrorism

I was going to write something about the foolishness of adding cameras to public spaces as a response to terrorism threats, but Scott Henson said it already:

Homeland Security Ubermeister Michael Chertoff just told NBC’s Tim Russert on Meet the Press this morning that the United States should invest in “cameras and dogs” to protect subway, rail and bus transit systems from terrorist attacks.


Surveillance cameras didn’t deter the terrorist attacks in London. They didn’t stop the courthouse killing spree in Atlanta. But they’re prone to abuse. And at the end of they day they don’t reduce crime.

Posted on July 12, 2005 at 8:13 AM35 Comments


david July 12, 2005 8:39 AM

See, there are even MORE foolish responses than cameras available. I know, that’s no excuse.

Note that the mode in which cell phones have been used to detonate bombs, using the built-in alarm function, is unaffected by Big Brother’s heroic actions here. Not to mention that always defending against the attack that already happened is the surest sign of a dinosaur that simply doesn’t know yet it’s dead, nor had the sense yet to fall down.

OWell. Maybe now that there’s been an attack against some other mode, some of the insanity at the airports will begin to subside.

egeltje July 12, 2005 8:45 AM

That point on the alarmclock of the mobile is something nobody likes to hear. It is far mor appealing to have remote controlled bombs (so we can impose some control on the GSM network), than the modern equivalent of the old fashioned hand-wired alarmclock.

D. July 12, 2005 8:54 AM

Ok, we all know that it doesn’t work but that doesn’t change the fact that people won’t think otherwise. How do we convince the public and most importantly politicians to think otherwise?

PeteM July 12, 2005 9:12 AM


“It is far mor appealing to have remote controlled bombs (so we can impose some control on the GSM network)”

Last Thursday most of the mobile networks went down in London. I have been told by a Metropolitain Police Constable that it was shut down in case mobiles were being used to trigger the bombs although this can not have been the case in the three tube bomb cases.

I have also heard it said that this down time was caused by deliberately locking out all private phones to give more band width to the emergency services which is a feature that has been confirmed to exist in the UK network.

B. July 12, 2005 9:14 AM

While I agree with both you (Bruce) and Scott, I think that there’s a fundamental disconnect between the argument Chertoff makes and that which is made by Mr. Henson.

Chertoff suggests that ‘cameras and dogs’ should be used “to protect” while Mr. Henson’s reply focuses on prevention and deterrence.

If, through the use of ‘cameras and dogs’, you are able to detect and respond to a threat, then there was not a reduction in crime nor were the attackers deterred. However, their plot was unable to be seen to completion and the end result was a failure.

This is not to say that I would expect every attempt to be caught via these methods. And, again, let me say I don’t agree with the expenditure of resources on this sort of project. I don’t think that it would actually provide a reduction in successful attacks. However, I think it’s important to address the points brought up by the proponents of increased surveillance rather than just talking past them.

Rampo July 12, 2005 9:19 AM

Consider this: an Australian study now shows that mobile phone usage while driving quadruples the risk of an accident:

even when using a hands-free kit.

The UK government made using non-hands-free mobile phones while driving illegal, because the public perceived that it was dangerous. There is no chance that the UK government will make all mobile-phone usage while driving illegal (even though it would apparently save lives), because it doesn’t look dangerous to the public.

That is the nature of public safety legislation these days.

Andre LePlume July 12, 2005 9:33 AM

On the point of legislatively banning a useful technology because it can be used as a low-tech timing device for an explosive, consider the case of the American filmmaker recently imprisoned by US forces in Iraq, and held w/out access to an attorney, his family, etc.

This former Navy SEAL, in-country to make a film about an Iraqi history, was riding in a taxicab which also carried washing machine timers. Ergo, he needed to be interrogated for two months. Washing machine timers can be used as timers for IEDs.

Keeping the electricity off in the majority of the country is a clever plan to render washing machines useless, thus demonstrating that whoever possesses as washing machine timer must be an evildoer. Clever.

Chris July 12, 2005 9:46 AM

On the cellphone subject (which is off-topic…)

According to much of the service has been restored. Apparently many people are unaware of the lessons of Flight 93, of the benefits of widespread communication.

Incidentally (ok, not so incidentally) most of the cellphones I have owned have a configuration feature that provides for audible alerts in the event of a loss of signal. So, the deliberate blocking or cutting the signal in tunnels could be mis-used as a signal that the train is now in the tunnel, something that previously would have been possible to only predict, not actually measure.

This is similar to the trigger signals on IED’s ( ), although making it possible with cellphones seems to be making the wrong job too easy.

Henry July 12, 2005 10:12 AM

Once again you abuse your position of trust to spread lies and FUD. No-one thinks a suicide bomber will be deterred by cameras, but criminals might.

Also, many crimes are committed by repeat offenders. Cameras increase the rate of detection and prosecution, and so prevent crimes which may otherwise have occurred.

Real-time monitoring systems are only improving and are getting to the point where they are detecting suspicious behavior which can then be followed up by real people.

Why do you always have to go for all or nothing answers, when you know that there is no single solution but that single solutions can have a real effect? How about you talk about liquidity instead of absolutes, about cutting crime instead of eliminating it?

I remember one comment on your blog when you talked about the senior judge who accidentally took a knife on board. The commenter said words to the effect: ‘no, you don’t understand, if we let judges carry knives then the terrorists will just recruit judges’. It demonstrates the flaws in your thinking perfectly. Grow up and start being sensible.

Bruce Schneier July 12, 2005 10:34 AM

“Also, many crimes are committed by repeat offenders. Cameras increase the rate of detection and prosecution, and so prevent crimes which may otherwise have occurred.”

Actually, cameras do not. Every study I’ve read concludes that they have no effect on crime. They cost money, and do no good.

“Why do you always have to go for all or nothing answers, when you know that there is no single solution but that single solutions can have a real effect? How about you talk about liquidity instead of absolutes, about cutting crime instead of eliminating it?”

I think you’re misreading me. Everything I write tries to fight the “all or nothing” approach to security. Security is always a trade-off. It’s always a matter of degree. It is never all or nothing.

Cameras have a place in the security toolkit. There are some instances where the benefits of the cameras outweigh the costs. There are many more where they do not. I hope I’ve never implied otherwise.

Zwack July 12, 2005 11:07 AM


I thought that it was public knowledge that cell phone circuits in the UK can be switched to an “emergency services” only mode. I believe you can still make 999 calls in that mode (the British equivalent of 911) and the rest of the bandwidth is reserved for phones used by emergency services personnel. It makes sense while in the immediate vicinity of an emergency situation that non emergency calls are curtailed. Flight 93 wouldn’t have been affected as it was not in the area of the emergencies, and unless everyone calling flight 93 was in New York or Washington then it wouldn’t be an issue.

So, I guess it comes down to do you risk having the phone network jammed from over use or do you reduce communications in as small an area as possible?


nick gully July 12, 2005 11:19 AM

I’ve already read in a few places “gee, the london camera system didn’t work”. It may not prevent
a particular suicide bombing, but it can let you trace the path of people in the aftermath.

On the one hand I don’t want to live in a police state, on the other, this is a valuble tool.

A Democratic Pan-Opticon:
A city is covered with cameras like London.
The cameras take photos on average every 30 seconds, but pseudo-randomly shift within those periods to avoid timing attacks.
You have to register to view the photos.
Anyone can view those photos.
The photo page registers everyone who views that photo.
Nobody can remove images.

This has the advantage of “no more secrets”, but the disadvantage is that it could be used for criminal activity to spot security measures that “rely” on secrecy, i.e. “when does the bakery owner walk to the bank to deposit cash”. But in the end you could check the logs to view who was a
“witness” to the crime or the camera.

roberton July 12, 2005 11:37 AM

Regarding the news about an Australian study on mobile phone usage.

@Rampo states that using a non-hands-free mobile was made illegal “because the public perceived that it was dangerous”.
I think this is true. Many people do think that driving a car one-handed is more dangerous than keeping two hands on wheel. I take it you disagree?! 🙂

I agree that legislation is often passed because it appears to improve safety when actually it may not. However, I think we must also be careful not to jump on each and every report that tries to either establish or disprove a link between an activity and a risk. There isn’t a lot of detail in the BBC report, but it outlines the methodology and it didn’t strike me as conclusive. I’d have to see a lot more evidence before being sure.


TG July 12, 2005 11:45 AM

Cameras function as a log of activities and can possibly be used to catch bad guys. Cameras probably will not deter a suicide bomber but maybe we can learn from the video. I can not see any easy way of dealing with this. Ideas?

Bruce Schneier July 12, 2005 12:14 PM

“Cameras function as a log of activities and can possibly be used to catch bad guys. Cameras probably will not deter a suicide bomber but maybe we can learn from the video. I can not see any easy way of dealing with this. Ideas?”

Agreed. The primary use of security cameras is for audit. They make sense in banks and some high-crime-rate retail stores for precisely this reason.

But again, it all gets back to the security trade-off. Cameras severely limit liberty. Is the additional security worth it? Usually not, but sometimes yes.

I would hope there are security cameras all over nuclear weapons storage facilities, for example.

Tom July 12, 2005 12:41 PM

It seems all four bombers were caught on CCTV cameras before the London bombings.

Yes CCTV don’t do much to stop crime, but at least we can find the offenders afterwards.

Clive Robinson July 12, 2005 1:16 PM


“Agreed. The primary use of security cameras is for audit.”

Actually in the UK they serve two purposes only. Privatly owned systems are there to reduce costs (security personnel and insurance). Government / Public Authority owned ones are for collecting fines for road tax evasion, speading, and other revenue generating purposes.

Sorry to bang on about it but the majority of road side cameras are used as a back door taxation system (see recent anouncments about road tolls made by Alister Darling).

Just perform a simple ROI calculation and you will realise that there cannot be any other reason. If you are going to invest 10 Billion USD in security cameras, you are most definatly going to want to see a payback that is atleast an order of magnitude greater than that. You most certainly will not make it in savings in other areas, so…

@Rampo & roberton

You have missed the point of the legislation, which was a 20GBP (35USD) on the spot fine, which is effectivly kept by the Police authority. So central government can reduce the funding to them, basically it’s a stealth tax.

Unfortunatly it does not work as the Police find it’s more expensive to stop a motorist and issue the ticket / collect the money than they make out of it, so few if any tickets are issued now.

They do not turn off the cell-phone signal, they just tell you the number you are calling is busy… This has two benifits, one the service is still available for the “Emergency Service” phones, the second if you think the number you are calling is engaged you will stay off the air longer than if you just get the voice mail. So it would not work as a bomb detonator.

David July 12, 2005 1:55 PM

If you put cameras on every corner, require all people to carry identification, possibly embedded with RFID tag, we can track everyone. But is that security or is that a lack of security?

Every day we walk our streets here without any cameras or IDs, and the streets are safe.

Any solution that pretends that culture is not critical will miss the point.

Safety doesn’t come from adding more survellience. Sure, high value targets need these, such as banks, nuclear facilities, etc. because they are frequent targets for criminals.

Our safety will come through justice and social expectations, along with adequate legal responses to those who violate the law.

John Koetsier July 12, 2005 2:07 PM

Tom, the last poster, has the most intelligent comment to date. Also, coincidentally, the most common sense.

I hate cameras too, and would vote for the Pan-Opticon solution rather than a closed one where I don’t know who’s watching, but being able to at least catch the bad guys is a step in the right direction.

Chris July 12, 2005 2:42 PM

@Clive Robinson

“They do not turn off the cell-phone signal, they just tell you the number you are calling is busy…
This has two benifits…

Thanks for the explanation on how the London ‘restricted access’ mode appears to end users. The primary purpose appears to be preserving bandwidth for emergency use, which it does. It would have been more useful to more people however, if it indicated that your call would never go through – users could then possibly switch to text messages, which can be delayed (unlike a voice call) and which consume only a small fraction of the bandwidth of a voice call. It might even save a little more bandwidth as users stop trying calls, and word-of-mouth in the vicinity carries the message that cell networks are diverted to emergency calls.

However – my comments were referring to the New York transit decision to completely cut service in some of the tunnels. Not the same thing at all – one of the criticisms of the New York decision is that when service is cut, not even emergency services can use those networks.

Adam Fields July 12, 2005 5:00 PM


I’m told that London has 500,000 surveillance cameras. How about someone over there demand some hard evidence about whether this IS working?

Dylan July 12, 2005 6:28 PM

I think you begin to see some evidence today with information about the raids in Leeds and the video survellance of the bombers entering King’s Cross.

In this instance, video surveillance has helped to speed up the detection process. If these were not suicide bombers (like in Madrid, where the bags were left on the trains unattended) then quicker detection would be the goal in preventing another event.

Even in the case of suicide bombers (as the London attacks now appear) quicker detection is more likely to lead to prevention of another set of suicide bombers from the same stable.

The cameras, however, do nothing to prevent terrorism in the long run. We don’t yet know what could do this, apart from broader social change, which I don’t necessarily see occuring in my lifetime. (After all, it has taken decades to bring us to this point. Why would it all change overnight?)

Richard Schwartz July 12, 2005 8:07 PM

@Dylan, et al.: if the cameras did help identify the bombers (as has been widely reported today, though certainly not proven yet), even if they are suicide bombers then they will have helped establish a foundation for a lot of follow-up police work. Surely, the British authorities will dig deep into the backgrounds of these men, look for known associates, follow money and material trails, etc. There is value to this, and there is value to the speed with which this process can start.

No, this won’t prevent another bombing by another group with no traceable connection to this group, but what if these four are part of a group of eight, four of whom can be in custody next week and unable to carry out their next bombing, or unable to carry on recruiting more bombers, then that’s a positive outcome. It won’t make terrorism go away, but it might make it less frequent.

Is it worth the cost — both direct and indirect — of surveillance cameras? I have no idea, and I suspect not. I suspect that the cameras were not crucial in identifying the four suspects, and if they cut any time from the process it was probably just a matter of a few hours.

Dylan July 13, 2005 1:05 AM

I wonder at the cost/benefit tradeoff of all these security cameras.

Compare and contrast with the cost/benefit tradeoff of developing and deploying the stealth bomber in Iraq.

Which has provided the best ROI?

david July 13, 2005 6:31 AM


I wonder at the cost/benefit tradeoff of all these security cameras.

Compare and contrast with the cost/benefit tradeoff of
developing and deploying the stealth bomber in Iraq.

Which has provided the best ROI?

How do you measure ROI in these two cases? Why are the comparABLE?

Chris July 13, 2005 8:39 AM

The security cameras have not been able to prevent the bombings in London but have helped, significantly, in the police investigation following the attacks. These leads will assist in hopefully preventing another attack and so it might be argued they have prevented a bombing. However, how do we prove the negative?
Personally, the use of surveillance cameras worries me less than mobile phone, profiling and snooping on net activity. However it is the potential to commercial/personal abuse, such as by employers or partners with a gripe, which would worry me.

Ed T. July 13, 2005 10:35 AM


However – my comments were referring to the New York transit decision to completely cut service in some of the tunnels. Not the same thing at all – one of the criticisms of the New York decision is that when service is cut, not even emergency services can use those networks.

Not only did they cut the service, then the fact was publicized — meaning the terrs now know about it, and will simply use another means to detonate the bombs (if they are so inclined.)

Adam Fields July 13, 2005 11:09 AM

@Chris, et al.
Okay, so I’ve read that the cameras have assisted in possibly identifying the bombers, some of whose ID also was found at the scene.

The cameras can’t be said to be a deterrent to suicide bombers, because I’d assume that those people >want< you to know who they are after the fact.

More importantly, these people were completely unknown to the intelligence community and had no previous known ties to radical groups.

If these were “traditional bombers”, maybe there’s some value there, but that’s not your threat model. Your threat model is unknown, locally born suicide bombers who don’t care what you know after they’ve done their thing. Surveillance cameras aren’t a deterrent, ID infrastructures are useless, no matter how much money is spent. Even with perfect surveillance and perfect ID, these guys wouldn’t have been suspects.

In my opinion, the response has to be to simultaneously address the root causes that make these people want to blow themselves up, make it socially unacceptable to exhibit that kind of behavior, and try to stop the flow of the apparently military grade explosives they’re using to do it.

Davi Ottenheimer July 13, 2005 3:25 PM


You suggest “foolishness of adding cameras to public places”, and say that “cameras severely limit liberty”.

This is unfair. I must completely disagree with your statements as they are misleading to the point of suggesting a false conclusion.

I feel you need to first acknowedge that the technology should not be blamed.

Abuse of technology is a problem that needs to be adressed, but it should not overshadow the reality that surveillance camera technology today is very, very useful as a detective control, and it is actually getting better by the minute.

Cameras also can serve a preventative purpose, and I could give specific examples here, but nobody really considers that their primary purpose. Moreover, the preventative effects are most often really just a form of social engineering rather than anything technical or related to cameras. In other words, in many cases I have found that if you tell people “watch out for surveillance bears” you will see a rapid shift in behavior around teddy-bears, including a reduction in petty theft, etc. until people realize the ruse, etc.. Note, just the threat of surveillance can sometimes be as debilitating to an organization as an actual attack, since people sometimes overreact to the unknown, especially with regard to “futuristic” surveillance technology.

Let’s face it, like any preventative control (like locks) determined criminals will find it easy to bypass at least one or two controls. The more expert/seasoned the attacker, the less the controls stand a chance on their own. Alas, we should not assess each control alone to determine risks.

Ironically, I am late to this thread because I have been busy deploying some new networked camera surveillance technology. So I feel I must also mention that past studies of surveillance technology are often about as useful to today’s discussion as the green-screen studies from the 1980s talking about problems with UI design. Show me a study that can keep up with the reality of the new systems and takes progress into account, eh? Take millimeter wave scanning as a good example of something that could revolutionize the role of cameras. What study can you reference that includes an assessment of the impact of detecting weapons automatically and sending alerts with video? The technology is changing exponentially, with amazing advances that parallel the digital camera revolution (focus, aperture, size, resolution, weight, etc.).

And finally, I often overcome initial resistance to cameras (and fear of loss of liberties) by explaining the concept of surveillance from a more familiar perspective. I mean when you walk into a small town, or a village, surveillance is all around you. Do you lose your rights because someone is sitting on their porch watching you? Do you lose your rights because gossip is in the air, based on what someone saw? The cameras really just allow our increasingly distributed environments to become small again.

When space goes from big to small in such a short time-frame, collision of values is to be expected. Who should get to see the images? How can we ensure an assessment/exposure of images will be fair and just? But the cat is out of the bag with regard to digital cameras. Cameras in public places are inevitable for a host of reasons, many of which map directly to why public places are made “public” in the first place (e.g. for everyone to enjoy safely). The question is really just how and when the technology can be reliably deployed and managed in a manner consistent with our shared values.

Davi Ottenheimer July 13, 2005 6:19 PM

Interesting to also note that the cameras on the buses were not actually working:–58–the-hunt-name_page.html

“the investigation received a serious setback when it was discovered the CCTV cameras on the bus that blew up were not working so detectives will not get vital images of the bomber.

One senior Yard source said: ‘It’s a big blow and a disappointment. If the cameras had been running we would have had pin-sharp close-up pictures of the person who carried out this atrocity. We don’t know if the driver forgot to switch them on or if there was a technical problem but there are no images.’

The bus had four cameras – one covering people getting on, the second at the exit doors and one on each deck scanning the length of the vehicle.”

Davi Ottenheimer July 13, 2005 6:40 PM

Stop me if I’m beating a dead horse here, Bruce, but if you look specifically at the studies you provide as examples/links, you get interesting insight into why cameras supposedly “fail”.

For example, the link quotes a report that states “Six of the 14 control rooms were left unstaffed for part of the day or night. And in some cases, cameras could not capture clear images at night due to the glare from artificial lights.”

Enhanced technology easily solves not only the latter (newer cameras are better able to deal with lighting issues) but also the former issue. If they move to today’s more sophisticated automated alerting systems that do not require constant staffing, then they will also reduce the risk of an inoperable or poorly managed system.

And here’s another key quote:

“Professor Gill said that because government funding was available for CCTV schemes, local officials tended to fit the cameras without any clear goal in mind.”

Security systems deployed without any goal? You can hardly declare that as proof cameras will never serve a useful purpose in serving public security.

Nick Barron July 14, 2005 2:19 AM

@Adam, “Your threat model is unknown, locally born suicide bombers who don’t care what you know after they’ve done their thing.”

That’s true, but it seems (based on the currently released information) unlikely that they were acting alone. So it is still worthwhile being able to track the social network in order to prevent future incidents.

Regarding CCTV, I think it’s still too early to say whether CCTV evidence was instrumental in the investigation; all that’s been confirmed so far is that the four current suspects were seen together on CCTV; how significant this evidence was is not known to the public.

Bill McGonigle July 14, 2005 12:19 PM

Richard is on the right track here. There’s already a generation of salafist jihadists that’s ruined and can’t be fixed. If the cameras can identify them (the big If) then we can possibly go find their organization. From there we can query, arrest, or kill the appropriate people.

They key here is there isn’t a deterrent that’s going to be effective against these people and there’s nothing you can do to completely guard against them. So you have to accept that there will be successful attacks and you need to either preempt those attacks or have an effective response to them. Which is better is a separate debate (and usually an intense debate reflects that the correct answer is ‘both’).

Now then, you also have to ensure that the next generation doesn’t become a new wave of salafist jihadists and I don’t see nearly enough work happening on that front, especially from mainland Europe. One wonders what’s being discussed in Denmark and Italy right now.

security cameras & me July 19, 2005 11:09 AM

Cameras will provide some evidence of the crime and help the authorities back track to see if anyone helped them along the way. Perhaps a camera could capture a license plate number of a car that dropped off a suicide bomber. Perhaps that would lead to the arrest of other potential suicide bombers thus saving lives, perhaps your own. In this way, they do infact prevent crime. Without them, more crimes are undeterred.

Andrew Cropper January 8, 2007 6:11 AM

I’m currently doing my dissertation on surveillance technology and have written a questionnaire regarding various issues including tagging of criminals, CCTV cameras, tagging phone calls, etc.

I agree that surveillance hasn;t exactly feel safer as it’s not exactly stopping these killings across the world, etc

If anybody could email me I would be grateful if you could fill in a questionnaire for me???

Thanks in advance
Andrew Cropper

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