Surveillance Technology: The Universal Panopticon

The trend began in Britain a decade ago, in the city of King’s Lynn, where sixty remote controlled video cameras were installed to scan known “trouble spots,” reporting directly to police headquarters. The resulting reduction in street crime exceeded all predictions; in or near zones covered by surveillance, it dropped to one seventieth of the former amount. The savings in patrol costs alone paid for the equipment in a few months. Dozens of cities and towns soon followed the example of King’s Lynn. Glasgow, Scotland reported a 68% drop in citywide crime, while police in Newcastle fingered over 1500 perpetrators with taped evidence. (All but seven pleaded guilty, and those seven were later convicted.) In May 1997, a thousand Newcastle soccer fans rampaged through downtown streets. Detectives studying the video reels picked out 152 faces and published eighty photos in local newspapers. In days, all were identified.

David Brin, The Transparent Society, chapter 1, p. 51

In the early nineteenth century, Jeremy Bentham, one of the oddest and most original of English thinkers, designed a prison where every prisoner could be watched at all times. He called it the Panopticon. Elements of his design were later implemented in real prisons in the hope of better controlling and reforming prisoners. If Brin is correct, it is now in the process of being implemented on a somewhat larger scale.

The case of video surveillance in Britain suggests one reason – according to British reports it provides an effective and inexpensive way of fighting crime. In the United States, cameras have long been used in department stores to discourage shoplifting. More recently they have begun to be used to apprehend drivers who run red lights. While there have been challenges on privacy grounds, it seems likely that the practice will spread.2

Crime prevention is not the only benefit of surveillance. Consider the problem of controlling auto emissions. The current approach imposes a fixed maximum on all cars, requires all to be inspected, including new cars that are almost certain to pass, and provides no incentive for lowering emissions below the required level. It makes almost no attempt to selectively deter emissions at places and times when they are particularly damaging.

One could build a much better system using modern technology. Set up unmanned detectors that measure emissions by shining a beam of light through the exhaust plume of a passing automobile; identify the automobile by a snapshot of the license plate. Bill the owner by amount of emissions and, in a more sophisticated system, when and where they were emitted.3

Another application of large-scale surveillance already being experimented with takes advantage of the fact that cell phones continually emit positioning cues, untraced signals produced in the process of keeping track of what tower they should communicate with. By monitoring the signals from drivers’ phones, it is possible to observe traffic flows. That is very useful information if you want to advise drivers to route around a traffic jam, or locate an accident by the resulting cluster of phones. Currently it is anonymous information, locating a phone but not identifying its owner. As technology evolves that may change.

None of these useful applications of technology poses, at first glance, a serious threat to privacy. Few would consider it objectionable to have a police officer wandering around a park or standing on a street corner, keeping an eye out for purse snatchers and the like. Video cameras on poles are merely a more convenient way of doing the same thing – comfortably and out of the wet. Cameras at red lights, or photometric monitoring of a car’s exhaust plume, are cheaper and more effective substitutes for traffic cops and emission inspections. What’s the problem?4

The problem comes when we combine this technology with others. A cop on the street corner may see you, he may even remember you, but he has no way of combining everything he sees with everything that every other cop sees and so reconstructing your daily life. A video camera produces a permanent record. It is now possible to program a computer to identify a person from a picture of his face.5 That means that the videotapes produced by surveillance cameras will be convertible into a record of where particular people were when. Add in the ability of modern data processing to keep track of enormous amounts of information and we have the possibility of a world where large fractions of your doings are an open book to anyone with access to the appropriate records. Add to that the ability of computers to identify suspicious patterns of behavior, something already being experimented with in several places,6 and those in control of the technology cannot only look at everything but know where to look.

So far I have been discussing the legal use of surveillance technology, mostly by governments – already happening on a substantial scale and likely to increase in the near future. A related issue is the use of surveillance technology, legally or illegally, by private parties. Lots of people own video cameras and those cameras are getting steadily smaller; even more people own cell phones with cameras built in. One can imagine, a decade or two down the road, an inexpensive video camera with the size and aerodynamic characteristics of a mosquito. The owner of a few dozen of them could collect a lot of information about his neighbors – or anyone else.

Of course technological development, in this area as in others, is likely to improve defense as well as offense. Possible defenses against such spying range from jamming transmissions to automated dragonflies programmed to hunt down and destroy video mosquitoes. Such technologies might make it possible, even in a world where all public activities were readily observable, to maintain a zone of privacy within one’s own house.

Then again, they might not. We have already had court cases over whether it is or is not a search to deduce marijuana growing inside a house by using an infrared detector to measure its temperature from the outside.7 We already have technologies that make it possible to listen to a conversation by bouncing a laser beam off a window and reconstructing from the measured vibrations of the glass the sounds that cause them. Even if it is not possible to spy on private life directly, further developments along these lines may make it possible to achieve the same objective indirectly.

Assume, for the moment, that the offense wins out over the defense – that preventing other people from spying on you becomes impractical. What options remain?

Brin argues that privacy will no longer be one of them. More interestingly, he argues that that may be a good thing. He proposes as an alternative to privacy universal lack of privacy: the transparent society. The police can watch you – but someone is watching them. The entire system of video cameras, including cameras in every police station, is publicly accessible. Click on the proper web page – read, presumably, from a handheld wireless device – and you can see anything that is happening in any public place. Parents can keep an eye on their children, children on their parents, spouses on each other, employers on employees and vice versa, reporters on cops and politicians.

The Upside of Transparency

Many years ago I was a witness to a shooting; one result was the opportunity for a certain amount of casual conversation with police officers. One of them advised me that, if I ever happened to shoot a burglar, there were two things I should make sure of: that he ended up dead and that the body ended up inside my house.

The advice was well meant and perhaps sensible – under U.S. law a homeowner is in a much stronger legal position killing an intruder inside his house than outside, and a dead man cannot give his side of the story. But it was also, at least implicitly, advice to commit a felony. That incident, and a less friendly one in another jurisdiction where I was briefly under arrest for disturbing the peace (my actual offense was aiding and abetting someone else in asking a policeman for his badge number), convinced me that at least some law enforcers, even ones who are honestly trying to prevent crime, have an elastic view of the application of the law to themselves and their friends. The problem is old enough to be the subject of a Latin tag – Qui custodes ipsos custodiet. “Who shall guard the guardians?”

The transparent society offers a possible solution. Consider the Rodney King case. A group of policemen captured a suspect and beat him up – a perfectly ordinary sequence of events in many parts of the world, including some parts of the United States. Unfortunately for the police, a witness got the beating on videotape, with the result that several of the officers ended up in prison. There have been a number of similar cases since then.8 Law enforcement agents, in deciding just how far they can go beyond what the public might approve of, must take account of the possibility that somebody might have a video camera pointed their way. In Brin’s world, every law enforcement agent knows that he is on candid camera all of the time and conducts himself accordingly.

It is an intriguing vision and it might happen. But there are problems.

Selective Transparency

The first is getting there. If transparency comes, as it is coming in England, in the form of cameras on poles installed and operated by the government, Brin’s version does not seem likely. All of the information will be flowing through machinery controlled by some level of government. Whoever is in charge can plausibly argue that although much of that information can and should be made publicly accessible, there ought to be limits. And even if they do not argue for limits, they can still impose them. If police are setting up cameras in police stations, they can arrange for a few areas to be accidentally left uncovered. If the FBI is in charge of a national network it can, and on all past evidence will, make sure that some of the information generated is accessible only to those whom they trust not to misuse it – most of whom are working for the FBI.

The situation gets more interesting in a world where technological progress enables private surveillance on a wide scale, so that every location where interesting things might happen, including every police station, has flies on the wall watching what happens and reporting back to their owners. A private individual, even a large corporation, is unlikely to attempt the sort of universal surveillance that Brin imagines for his public system, so each individual will be getting information about only a small part of the world. But if that information is valuable to others, it can be shared. Governments might try to restrict such sharing. But in a world of strong privacy that will be hard to do, since in such a world information transactions will be invisible to outside parties. Combining ideas from several chapters of this section, one can imagine a future where Brin’s transparent society is produced not by government but by private surveillance.

A universal spy network is likely to be an expensive proposition, especially if you include the cost of information processing – facial recognition of every image produced and analysis of the resulting data. No single individual, probably no single corporation, will find it in its interest to bear that cost to produce information for its own use, although a government might. The information will be produced privately only if the producer can both use it himself and sell it to others. So a key requirement for a privately generated transparent society is a well-organized market for information.9

The Downside of Transparency

Following Brin, I have presented the transparent society as a step into the future, enabled by video cameras and computers. One might instead view it as a step into the past. The privacy that most of us take for granted is to a considerable degree a novelty, a product of rising incomes in recent centuries. In a world where many people shared a single residence, where a bed at the inn was likely to be shared by two or three strangers, transparency did not require video cameras.

For a more extreme example, consider a primitive society such as Samoa. Multiple families share a single house – without walls. While there is no internet to spread information, the community is small enough to make gossip an adequate substitute. Infants are trained early on not to make noise. Adults rarely express hostility.10 Most of the time, someone may be watching – so you alter your behavior accordingly. If you do not want your neighbors to know what you are thinking or feeling, you avoid clearly expressing yourself in words or facial expression. You have adapted your life to a transparent society.

Ultimately this comes down to two strategies, both familiar to most of us in other contexts. One is not to let anyone know your secrets – to live as an island. The other is to communicate in code, to use words or expressions that your intimates will correctly interpret and others will not. For a milder version of the same approach, consider parents who talk to each other in a foreign language when they do not want their children to understand what they are saying, or a translation of a Chinese novel I once came across, with the pornographic passages translated into Latin instead of English.11

In Brin’s future transparent society, many of us will become less willing to express our opinions of our boss, employees, ex-wife, or present husband in any public place. People will become less expressive and more self-contained, conversation bland or cryptic. If some spaces are still private, more of social life will shift to them. If every place is public, we have stepped back at least several centuries, arguably several millennia.


Think of “privacy” as shorthand for an individual’s ability to control other people’s access to information about him. If I have a legal right not to have you tap my phone but cannot enforce that right – the situation at present for those using cordless phones without encryption – then I have little privacy with regard to my phone calls. I have almost complete privacy with regard to my own thoughts, even though it is perfectly legal for other people to use the available technologies – listening to my voice and watching my facial expressions – to try to figure out what I am thinking. Privacy in this sense depends on a variety of things, including both law and technology. If someone invented an easy and accurate way of reading minds, privacy would be radically reduced even if there were no change in my legal rights.12

One reason to define privacy in this way is that I am interested in its consequences, in the ways in which my ability to control information about me benefits or harms myself and others – whatever the source of that ability may be. Another is that I am interested in the ways in which technology is likely to change the ability of an individual to control such information – hence in changes in privacy due to sources other than changes in my legal rights.


Many people go to some trouble to reduce the amount others can find out about them. Many people, sometimes the same people, make an effort to get information about other people. This suggests an interesting question: On net, is an increase in privacy good or bad? Do I gain more from your being unable to find out things out about me than I lose from my being unable to find out things about you?

Most people seem to think that the answer is yes. It is common to see some new product, technology, or legal rule attacked as reducing privacy, rare to see anything attacked as increasing privacy. Why?

The reason I value my privacy is straightforward: Information about me in the hands of other people sometimes permits them to gain at my expense. They may do so by stealing my property – if, for example, they know when I will not be home. They may do so by getting more favorable terms in a voluntary transaction – if, for example, they know just how much I am willing to pay for the house they are selling.14 They may do so by preventing me from stealing their property – by, for example, not hiring me as company treasurer after discovering that I am a convicted embezzler.

Information about me in other people’s hands may also benefit me – for example, the information that I am honest and competent. But privacy does not prevent that information from being available to them. If I have control over information about myself I can release it when, and only when, doing so is in my interest.15

My examples included one – where my privacy protects me from burglary – in which privacy produced a net benefit, since the gain to a burglar is normally less than the loss to his victim. It included one – where my privacy permitted me to steal from others – in which privacy produced a net loss. And it included one case – bargaining – where the net effect appeared to be a wash, since what I lost someone else gained.16

Looked at more carefully, that third case is probably a net gain. One of the risks of bargaining is bargaining breakdown when a seller overestimates the price a buyer is willing to pay or a buyer makes the corresponding mistake the other way and the deal falls through, making both parties worse off than if they had each more accurately read the other. Privacy makes it harder to know things about other people – buyers and sellers are, after all, deliberately misrepresenting what they are willing to offer or accept in the hope of getting a better deal – making bargaining breakdown more likely. It looks as though privacy produces, on average, a net loss in situations where parties are seeking information about each other in order to improve the terms of a voluntary transaction, since it increases the risk of bargaining breakdown.17 In situations involving involuntary transactions, privacy produces a net gain if it is being used to protect other rights (assuming that those rights have been defined in a way that makes their protection desirable) and a net loss if it is being used to violate other rights (with the same assumption). There is no obvious reason why the former situation should be more common than the latter. So while it is clear why I am in favor of my having privacy, it is not clear why I should expect my gains from my having privacy to outweigh my losses from your having it, why people should regard privacy, generally speaking, as a good thing.


It would have been impossible to proportion with tolerable exactness the tax upon a shop to the extent of the trade carried on in it, without such an inquisition as would have been altogether insupportable in a free country.

Adam Smith’s explanation of why a sales tax is impractical (Wealth of Nations Bk V, Ch II, Pt 2, Art. II)

The state of a man’s fortune varies from day to day, and without an inquisition more intolerable than any tax, and renewed at least once every year, can only be guessed at.

Smith’s explanation of why an income tax is impractical (Bk V, Ch II, Pt 2, Art. IV)

Although private parties occasionally engage in involuntary transactions such as burglary, most of our interactions with each other are voluntary ones. Governments engage in involuntary transactions on an enormously larger scale. And governments almost always have an overwhelming superiority of physical force over the individual citizen. While I can protect myself from my fellow citizens with locks and burglar alarms, I can protect myself from government actors only by keeping information about me out of their hands.18

The implications depend on one’s view of government. If government is the modern equivalent of Plato’s philosopher-king, individual privacy simply makes it harder for government to do good. If, on the other hand, a government is merely a particularly large and well-organized criminal gang, stealing as much as it can from the rest of us, individual privacy against government as an unambiguously good thing. Most Americans appear, judging by expressed views on privacy, to be close enough to the latter position to consider privacy against government as on the whole desirable, with an exception for cases where they believe that privacy might be used to conceal crimes substantially more serious than tax evasion.

Seen from this standpoint, one problem with Brin’s transparent society is the enormous downside risk. Played out under less optimistic assumptions than his, the technology could enable a tyranny that Hitler or Stalin might envy. Even if we accept Brin’s optimistic assumption that the citizens are as well informed about the police as the police are about the citizens, it is the police who have the guns. They know if we are doing or saying anything they disapprove of and respond accordingly, arresting, imprisoning, perhaps torturing or executing their opponents. We have the privilege of watching. Why should they object? Public executions are an old tradition, designed in part to discourage other people from doing things that might get them executed.

It does not follow that Brin’s prescription is wrong. His argument, after all, is that privacy will simply not be an option, either because the visible benefits of surveillance are so large or because the technology will make it impossible to prevent it. If he is right, his transparent society may at least be better than the alternative – surveillance to which only those in power have access, a universal Panopticon with government as the prison guards.

Say It Ain’t So

So far I have ignored one interesting problem with Brin’s world – verification. Consider the following courtroom drama:

My wife is suing me for divorce on grounds of adultery. In support of her claim, she presents videotapes, taken by hidden cameras, that show me making love to three different women, none of them her.

My attorney asks for a postponement to investigate the new evidence. When the court reconvenes, he submits his own videotape. The jury observes my wife making love, consecutively, to Humphrey Bogart, Napoleon, her attorney, and the judge. When quiet is restored in the courtroom, my attorney presents the judge with the address of the video effects firm that produced the tape.

With modern technology I do not, or at least soon will not, need your cooperation to make a film of you doing things; a reasonable selection of photographs will suffice. As Hollywood demonstrated with Roger Rabbit, it is possible to combine real and cartoon characters in what looks like a single filmstrip. In the near future the equivalent, using convincing animations of real people, will be something that a competent amateur can produce on his desktop. We may finally get to see John F. Kennedy making love to Marilyn Monroe, whether or not it ever happened.

In that world, the distinction between what I know and what I can prove becomes critical. Our world may be filled with video mosquitoes, each reporting to its owner and each owner pouring the information into a common pool, but some of them might be lying. When I pull information out of the pool I have no way of knowing whether to believe it.

There are possible technological fixes – ways of using encryption technology to build a camera that digitally signs its output, demonstrating that that sequence was taken by that camera at a particular time. But it is hard to design a system that cannot be subverted by the camera’s owner. Even if we can prove that a particular camera recorded a tape of me making love to six women, how do we know whether it did so while pointed at me or at a video screen displaying the work of an animation studio? The potential for forgery significantly weakens the ability of surveillance technology to produce verifiable information.

For many purposes, unverifiable information will do – if my wife wants to know about my infidelity but does not need to prove it. As long as the government running a surveillance system can trust its own people it can use that system to detect crimes or politically unpopular expressions of opinion. And video evidence will still be usable in trials, provided that it is accompanied by a sufficient evidence trail to prove where and when it was taken – and that it has not been improved since. It becomes more believable with redundancy – five video mosquitoes, belonging to five independent owners, showing the same thing happening.

Should We Abolish the Criminal Law?

Modern societies have two different systems of legal rules – criminal law and tort law – that do essentially the same thing. Someone does something that injures others. He is charged, tried, and convicted, and something bad happens to him as a result, which gives other people an incentive not to do such things. In the criminal system prosecution is controlled and funded by the state, in the tort system by the victim. In the criminal system a compromise is called a plea bargain, in the tort system an out of court settlement. Criminal law provides a somewhat different range of punishments – it is not possible to execute someone for a tort, for example, although it was possible for something very much like a tort prosecution to lead to execution under English law a few centuries back – and operates under somewhat different legal rules.19 But in their general outlines, the two systems are no more than slightly different ways of doing the same thing.

This raises an obvious question – is there any good reason to have both? Would we, for example, be better off abolishing criminal law entirely and instead having the victims of crimes sue the criminals?

One argument against such a pure tort system is that some offenses are hard to detect. A victim may conclude that catching and prosecuting the offender costs more than it is worth, especially if the offender turns out not to have enough assets to pay substantial damages. Hence some categories of offense may routinely go unpunished.

In Brin’s world that problem vanishes. Every mugging is on tape. If the mugger chooses to wear a mask while committing his crime we can trace him backwards or forwards through the record until he takes it off. While a sufficiently ingenious criminal might find a way around that problem, most of the offenses that our criminal law now deals with would be cases where most of the facts are known and only their legal implications remain to be determined. The normal crime becomes very much like the normal tort – an auto accident, say, where (except in the case of hit and run, which is a crime) the identity of the party and many of the relevant facts are public information. In that world it might make sense to abolish criminal law and shift everything to the decentralized, privately controlled alternative. If someone steals your car you check the video record to identify the thief, then sue for the car plus a reasonable payment for your time and trouble recovering it.

Like many radical ideas, this one looks less radical if one is familiar with the relevant history. Legal systems in which something similar to tort law dealt with what we think of as crimes – in which if you killed someone his kinsmen sued you – are common in the historical record.20 Even as late as the eighteenth century, while the English legal system distinguished between torts and crimes, both were in practice privately prosecuted, usually by the victim.21 One possible explanation for the shift to a modern, publicly prosecuted system of criminal law is that it was a response to the increasing anonymity that accompanied the shift to a more urban society in the late eighteenth and early nineteenth century.22 Technologies that reverse that shift may justify a reversal of the accompanying legal changes.

Where Worlds Collide

In Chapter 4 I described a cyberspace with more privacy than we have today. In this chapter I have described a realspace with less. What happens if we get both?

It does no good to use strong encryption for my email if a video mosquito is sitting on the wall watching me type. So strong privacy in a transparent society requires some way of guarding the interface between my realspace body and cyberspace. This is no big problem in the version where the walls of my house are still opaque.23 It is a serious problem in the version in which every place is, in fact if not in law, public. A low-tech solution is to type under a hood. A high-tech solution is some link between mind and machine that does not go through the fingers – or anything else visible to an outside observer.24

The conflict between realspace transparency and cyberspace privacy goes in the other direction as well. If we are sufficiently worried about other people hearing what we say, one solution is to encrypt face-to-face conversation. With suitable wireless gadgets, I talk into a throat mike or type on a virtual keyboard (keeping my hands in my pockets). My pocket computer encrypts my message with your public key and transmits it to your pocket computer, which decrypts the message and displays it through your VR glasses. To make sure nothing is reading the glasses over your shoulder, the goggles get the image to you not by displaying it on a screen but by using a tiny laser to write it on your retina. With any luck, the inside of your eyeball is still private space.

We could end up in a world where physical actions are entirely public, information transactions entirely private. It has some attractive features. Private citizens will still be able to take advantage of strong privacy to locate a hit man, but hiring him may cost more than they are willing to pay, since in a sufficiently transparent world all murders are detected. Each hit man executes one commission then goes directly to jail.

What about the interaction between these technologies and data processing? On the one hand, it is modern data processing that makes the transparent society such a threat – without that, it would not much matter if you videotaped everything that happened in the world, since nobody could ever find the particular six inches of videotape he wanted in the millions of miles produced each day. On the other hand, the technologies that support strong privacy provide the possibility of reestablishing privacy, even in a world with modern data processing, by keeping information about your transactions from ever getting to anyone but you. That is a subject we will return to in a later chapter when we discuss digital cash – an idea dreamed up in part as a way of restoring transactional privacy.


1 See David Brin's web site on these topics.

2  See, for instance, a story on cameras in Colorado schools, and a page (in German) on the use of closed circuit television in Germany.

3 For details, see Foldvary and Klein (2003).

4 Traffic surveillance at present suggests what people surveillance may be like in the future, since reading a license plate or transponder or toll tag is easier than recognizing a face.

5 While there have been problems with poor performance of the software, the technology has been getting better; it is now claimed that the best face recognition software is better at recognizing faces than most humans.

6 Surveillance camera feed to computer to recognize suspicious behavior: Chicago UK.

7 Kyllo v. United States 533 U.S. 27, 121 S.Ct. 2038 (2001). The court found, on a 5 to 4 vote, that it was a search.

8 See, for instance: UCLA Tasering video, Police violating their complaint policy.

9 Alternatively, a transparent society might be produced by something analogous to an open source project for producing software. Each participant contributes the information from his cameras and has access to the information from everyone’s cameras.

10 Freeman, 1983.

11 The novel was Golden Lotus, regarded as a classic of Chinese literature; the translation was probably the one by Clement Egerton. Presumably the theory was that readers well enough educated to translate the Latin were beyond carnal temptation. Three volumes have now appeared of a translation entirely into English by David Tod Roy, with two more volumes still to go.

12 This may not be an entirely hypothetical example. There is now some evidence that brain scans can be used to tell when someone is lying. As we come to understand the brain better, it may become possible to tell more about what people are thinking by observing what is happening in their brains. There is also some evidence that it may become possible to use brain scans to identify psychopaths, which raises additional issues.

13 For a more extensive discussion of the issues of this chapter, see Friedman, 2000, in which I use the term “privacy rights” for what I here call privacy. For a more general discussion of rights from a related perspective see Friedman, 1994. My mental privacy is not quite complete, but the only important exception is my wife.

14 One example occurs in the context of a takeover bid. In order for the market for corporate control to discipline corporate managers, it must be in the interest of someone to identify badly managed corporations and take them over. That depends on a takeover bid remaining secret long enough for the person responsible to accumulate substantial ownership at the pre-takeover price. In a very public world, that is hard to do. Currently it is also hard to do in the U.S. because of legal rules deliberately designed to limit the secrecy of takeover bids. The result is not, of course, to eliminate all takeover bids, or all market discipline over corporate managers—merely to reduce both below what they would be in a more private and less regulated market.

15 A possible exception is the case where the relevant information is negative – the fact that I have not declared bankruptcy, say – and third parties have no way of knowing whether I have acted to suppress it. If individuals have control over such information, then the absence of evidence that I have declared bankruptcy provides no evidence that I have not – so borrowers who have not declared bankruptcy in the past will be better off in a world where privacy rights with regard to such information are weak. The problem disappears if I can take an observable action – such as signing a legally enforceable waiver of the relevant legal privacy rights – that demonstrates that the information is not being suppressed.

16 Many of the points made in this part of the chapter can be found, in somewhat different form, in Posner, 1978, “The Right of Privacy” and Posner, 1978, “An Economic Theory of Privacy.” He finds the case for the general desirability of privacy to be weak. My arguments for privacy are in Friedman 2005 (2).

17 This might not be the case if we are frequently faced with situations where my gains from the bargain provide the incentive for me to generate information that is of value to other people as well. There is little point to spending time and money predicting a rise in wheat prices if everything you discover is revealed to potential sellers before you have a chance to buy from them. This is a somewhat odd case because, while successful speculation is both socially useful and profitable, there is no particular connection between the two facts, as pointed out in Hirschleifer, 1971. Hence the opportunity for speculative gain may produce either too much or too little incentive to obtain the necessary information. A second qualification is that it might not be the case if there were some completely verifiable way of dropping my privacy – of letting you know the highest price I was willing to pay in exchange for your letting me know the lowest price you were willing to accept. This brings us back to a point made in an earlier note – the difficulty of conveying believable information in a context where I have the power to select what information is conveyed.

18 An alternative approach might be political activity – lobbying Congress or making contributions to the police benevolent fund or participating in a revolution. For most individuals in a large society, myself included, such tactics are rarely worth their cost.

19 Writing in the eighteenth century, Blackstone described the appeal of felony, a private action for criminal – indeed capital – punishment, as still on the books but passing out of use. As he described it, “on an indictment, which is at the suit of the king, the king may pardon and remit the execution; on an appeal, which is at the suit of a private subject … the king can no more pardon it than he can remit the damages recovered in an action of battery.” (Blackstone, 1979, V4, ch. 23, p. 311). See Friedman, 2000, ch. 14, 15, 18.

20 Friedman, 1979. A killer would be sued by his victim’s relatives and, if he lost the case and refused to pay damages, at risk of being hunted down and killed by them.

21 Friedman, 1995. Some enforcement was by prosecution associations, private organizations to prosecute felonies committed against their (dues-paying) members. By joining such an association – the membership was public information – an individual precommitted to the prosecution of felonies committed against him, making deterrence a private good.

22 Davies, 2002, argues that the private prosecution system was successfully dealing with problems of urbanization and was replaced by public police for other reasons – concern with preventing insurrection and with eliminating causes of crime by reforming the poor.

23 I still have to worry about technologies for listening to the sound of my keystrokes and deducing from that what I am typing, or observing electromagnetic signals from my computer monitor at a distance.

24 In one experiment, individuals controlled a computer cursor by thinking – with their brain activity picked up by a cap that held sixty-four electrodes to detect brain activity. At the other extreme, keylogging is an approach to defeating computer privacy already in use – software that records your keystrokes as you operate your computer, saving them in a file that can later be used to reconstruct what you were doing; think of it as a virtual video mosquito watching you type. A story on the first criminal case involving keylogging.