September 11, 2001: the day everything changed. The day terrorist attacks on New York City and Washington DC laid bare the vulnerability of Western openness and freedom. The day that led to a war on terrorism, the invasion of Afghanistan and war with Iraq. The day that led to a Department of Homeland Security with unprecedented new powers to snoop on the private affairs of its citizens.

But did everything really change? Did September 11 mark a watershed after which it would no longer be possible for a democratic society to preserve its cherished tradition of freedom from intrusive surveillance by its government? At the time, the loss of this freedom seemed inevitable, the necessary price to pay for security in this new, more dangerous world. To combat terrorism it is necessary to detect and identify a tiny number of evildoers among the great mass of ordinary citizens, and broad surveillance seemed to be the only way to effect this.

But now, more than four years after the attacks, many are questioning this assumption and also questioning the effectiveness in actually detecting and foiling terrorist plots of the surveillance powers that were granted to the government. It is true that to date there has not been another major terrorist attack on US soil. But perhaps the same or higher degree of security could be achieved in ways that do not do so much violence to individual liberties.

Mainstream criticism
At first, the only voices raising such doubts were those of liberal privacy advocates and libertarian conservatives, but gradually these were joined by more mainstream commentators. This is the context of two recent books about government surveillance. Both books are by Washington DC lawyers who are familiar with privacy law. The Intruders: unreasonable searches and seizures from King John to John Ashcroft, by Samuel Dash, (Rutgers University Press, New Brunswick NJ, 2004) is the more scholarly of the two works. Starting from the Magna Carta and British common law, Dash examines important US Supreme Court decisions interpreting the Fourth Amendment, which prohibits "unreasonable" searches and seizures.

The other book, The Naked Crowd: reclaiming security and freedom in an anxious age, by Jeffrey Rosen (Random House, New York, 2004) is written in a more popular style, focusing on recent developments, especially new technologies for surveillance, and evaluating their effectiveness and impact.

Both authors are critical of the US administration's recent moves to increase surveillance, especially the promotion of the USA Patriot Act and the efforts to bolster it with even greater surveillance powers in proposed new legislation. They differ, however, in their criticisms and proposed solutions.

One thing on which Dash and Rosen agree is that broad surveillance not connected to any specific criminal investigation is not very effective in detecting or deterring crime. Rosen points to the experience in Britain over the past decade, during which time millions of closed-circuit television cameras were set up to monitor public spaces such as city streets and parks, airport terminals and train stations, parking lots, hospital waiting rooms and the like. Studies of their effectiveness have failed to show any impact on overall rates of violent crime. Auto theft, for instance, has declined while prostitution simply moved indoors. Other crimes have actually increased -- out of sight of the cameras.

But effectiveness is not really the point of such surveillance measures, Rosen says. Terrorism terrifies. And laws permitting intrusive government surveillance, or the adoption of invasive security measures at airports reassure the public that something is being done. Long waits at security barriers at airports are accepted as ways for the public to show their solidarity and atone for not having been vigilant enough before.

Hence, governments are able to adopt repressive measures with little dissent. Dash argues that the Bush administration has been using the September 11 attacks as an excuse to limit individual liberties. In doing this, it is following a long series of precedents such as the Alien and Sedition Acts of the 1790s, Lincoln's suspension of habeas corpus during the Civil War, and the interning of Japanese Americans during World War II.

Two aspects of privacy
Something that neither of these books considers in depth is the human right of privacy itself, since their focus is the Fourth Amendment. It may be useful to distinguish privacy as freedom from unwanted intrusions from privacy as control over disclosure. The two are related, since intrusions can be used to obtain information, and information, such as one's home address or telephone number, is what enables intrusion.

Of the two, unwanted intrusions seem to be what people object to most strongly. No one likes the telemarketer's phone call in the middle of dinner. On the other hand, although people may say that they want to limit what third parties know about them, in practice they often show by their actions that they value this aspect of privacy rather little. Simson Garfinkel, in his book Database Nation, observes that people are willing to allow their every purchase to be recorded by a credit card company, just so that they can accumulate bonus points for more shopping. Thus, if we were to try to justify a right of privacy based on social norms and expectations, it would actually be rather difficult to make a very strong case.

However, there are more fundamental grounds. Unwanted intrusions also interfere with our autonomy, our right to control what we do. A similar argument can be made about surveillance: the more others know about us, the more they can take advantage of us and exploit us. Even surveillance by a benign and discreet overseer can be dangerous. Jeremy Bentham's Panopticon is a vision of a prison in which the inmates are under constant surveillance but cannot see the observer or tell when they are being observed. As Bentham realized, it is not necessary for the surveillance to be actually continuous. The mere fact of knowing that they might be watched, he argued, would be sufficient to alter their behavior. Therefore, there is a very real concern that in the hands of government, surveillance could control behavior and stifle dissent.

Striking a balance
Returning to the Dash and Rosen books, we can ask what they propose in the way of realistic remedies for the recent encroachment on our right of privacy. That is, how can we best balance the competing claims of security and liberty in the post-September 11 age?

Dash closes his book with an impassioned plea: "The United States must show the terrorists that the liberty and freedom of its people are its impregnable shield and sword." Thus he argues that we need to return to the constitutional protections that have historically been upheld. It is not quite clear how he proposes that this be done: it seems he would hope that the USA Patriot Act and similar recent measures would be held unconstitutional by the Supreme Court, but his assessment of the Court's recent directions does not seem to hold much promise that this will occur. He interprets the Court's decisions as broadening and strengthening protections up until about 1970, and thereafter as retreating, and allowing so many exceptions and exclusions as to be ineffective in preventing abuse of surveillance powers.

Rosen is more practical and argues that it is possible to achieve security through measures that are much less invasive than those that are often adopted. For instance, he compares two devices that have been developed for scanning airline passengers passing through security checkpoints. One, which he dubs the "Naked Machine," produces a direct image of the passenger's body beneath the clothing, while the other, the "Blob Machine," renders the body as a mannequin-like figure, with any attached objects visible on its surface. But somehow the more invasive method is always the one that gets adopted, and in the absence of strong public pressure for more privacy, this will continue to be the case.

In conclusion, Rosen outlines four possible paths to an "escape from fear." The first is the Transparent Society, an unrealistic notion promoted by author David Brin, in which not only is there surveillance everywhere, but access to the surveillance data is also universal. The second path is to allow unlimited surveillance but restrict its use by law enforcement agencies to only the most serious crimes. The problem with this approach is creeping expansion of the scope of the use of the data. The third path is judicial oversight of law enforcement actions. He considers that courts in the US have not shown much vigor in protecting privacy in the past. So Rosen settles on the fourth path: relying on Congress to pass laws appropriately balancing freedom and security, and to exercise oversight of the actions of law enforcement and intelligence agencies.

Although September 11 changed many things, it did not change human nature. Those in power still seek to increase their power, and free societies must continue to be vigilant in defending their freedoms against encroachment by their governments. But in this struggle, democracy is often its own worst enemy: ultimately, the only guarantor of freedom is the will of the people, but often that will is fickle, short-sighted, and easily distracted by mundane concerns. If history is any guide, the path ahead will be full of bumps and reverses but as the memory of those terrible attacks recedes, and hysteria is replaced by thoughtful action, we can hope that the democratic institutions that have traditionally defended freedom will eventually prevail.

Associate Professor Bob Moniot teaches computer science at Fordham University in New York.