If you devote a sizable chunk of your time to writing about surveillance, you see grim predictions about "the end of privacy" bandied about with a numbing regularity—hell, I've got at least two books by that title on my shelf right now. Which may be why it took me a while to get around to Yale law prof Jed Rubenfeld's recent article "The End of Privacy" in the Stanford Law Review. Well, mea maxima culpa: Rubenfeld's essay is not another catalog of privacy threats, but rather a provocative reexamination of the meaning of the Fourth Amendment—one that manages to be simultaneously radical (in the sense of "going to the root"), novel, and plausible in a way I would not have thought possible so late in the game.

Rubenfeld's big apple-to-the-noggin idea is this: mainstream jurisprudence regards the Fourth Amendment as protecting an individual right to "privacy"—which in the late 20th century came to mean the individual's "reasonable expectation of privacy"—with courts tasked with "balancing" this against the competing value of security. This, the good professor argues, is basically backwards: the Fourth Amendment explicitly protects the "security" of our personal lives. Excavating a neglected 17th and 18th century conception of "security" leads to a new reading that both avoids well-known internal problems with the "reasonable expectation" view and helps us grapple with the thorny privacy challenges posed by new technologies.

The received view of the Fourth Amendment dates from the seminal 1967 case Katz v. United States. With the advent of the telephone—and the ability to tap it—the Supreme Court recognized that the old property-centric reading that wedded "search and seizure" to physical trespass was no longer tenable. Technology had made it too easy to intrude upon people's personal lives without intruding on their property. Hence the new doctrine that the Fourth Amendment "protects people, not places," and the substitution of "reasonable expectations" for property rights as the defining element of a government "search."

Government aggregation of personal information about citizens may, after all, affect our security even when the information is not "private" in the sense of "totally secret."

To summarize, very crudely, an extended and incisive argument, Rubenfeld reviews the familiar objections that this standard is either circular (what the government does affects expectations) or indeterminate (our broader social expectations of privacy are highly role- and context-dependent) and concludes that courts have attempted to navigate these shoals by tacitly relying on what he dubs the "Stranger Principle." That is, the private is what we would not disclose to a perfect stranger. A corollary to this principle is the "third party doctrine," which we see taking shape in United States v. Miller and Smith v. Maryland: what you do disclose to strangers is not private.

There is, as Rubenfeld notes, a practical problem here: if we take this doctrine seriously, the Katz holding is far too broad, and only our communications with intimates should be immune to wiretap. But he argues that this is merely symptomatic of a deeper problem: owing in large part to the influence of a seminal essay by Samuel Warren and Louis Brandeis, modern courts have "privatized" the Fourth Amendment, interpreting it as protecting a broad right to be left alone. On this reading, the government is just one more nosy neighbor, subject to the same limitations as anyone else, and for the same reasons. This, Rubenfeld argues, does violence to the Framers' concern with the specific dangers of government intrusion.

To be "secure"

As an alternative, Rubenfeld suggests we take a fresh look at the text of the Fourth Amendment:

The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated

He zooms in on two words in that famous clause that have been largely neglected in modern jurisprudence: "people" and "secure."

When we get to the Fifth Amendment, the Framers were apparently capable of speaking in the singular—"no person shall...nor shall any person be subject to..."—suggesting that the use of the plural in the Fourth may be significant. In other words, the Constitution is not just concerned with how government searches affect the interests of particular individuals who are subject to search or surveillance.

Moreover, Rubenfeld explains, "security" had a central place in the legal thought of the founding era, standing with "liberty" and "property" as part of the triumvirate of core rights enjoyed by free citizens. This is not, to be sure, the same "security" invoked by advocates of unchecked government surveillance powers. It is, rather, the "security" of knowing your personal life is in some sense sacrosanct—as contrasted with the pervasive insecurity that citizens of a police state live under. As a practical guide, Rubenfeld suggests a quasi-Kantian test of "generality" for government search and surveillance policies: what would be the effect on the sense of security in society as a whole if a certain type of search were widespread?

This may sound like a subtle distinction—and indeed, in many cases, Rubenfeld's reading yields the same results as a jurisprudence of "privacy." But a few examples make clear how a "security" interpretation of the Fourth Amendment would differ. Current thinking, for instance, sees no Fourth Amendment problem with the use of undercover informants, and no need to obtain a warrant for their use: what you tell another person, especially someone you don't know intimately, is no longer secret, and therefore no longer private. But the widespread use of informants, as the example of authoritarian societies shows, does seriously undermine the security of our persona lives—as captured in the excellent film The Lives of Others.

More obviously relevant to our recent experience with surveillance is the way a security-centered reading affects questions of standing. Civil liberties groups have sought to challenge warrantless NSA spying by arguing that surveillance "chills" the First Amendment rights of journalists and academics who speak with sources abroad, but courts have not been terribly receptive to this argument. Standing to bring suit generally requires some concrete evidence that the specific plaintiff's privacy has actually been violated—evidence that's hard to come by when wiretaps are highly secret, and may not ever result in a criminal case. But a program of warrantless wiretapping clearly affects the security of our personal communications (in the sense of the term used by the Framers), whether or not it intrudes on any particular person's privacy.

A jurisprudence of security might also prove useful in considering technologically novel forms of monitoring, such as public surveillance cameras or data mining. Government aggregation of personal information about citizens may, after all, affect our security even when the information is not "private" in the sense of "totally secret." The mainstream privacy-centric view, by contrast, fails to see an important constitutional difference between a vast database of personal information maintained by Google and one maintained by the FBI. Or consider the question of whether computers can eavesdrop, implicated in debates over when, exactly, communications filtered using computerized keyword or call-pattern analysis have been "acquired." A shift to a focus on security allows us to bypass the question of when, exactly, a target's privacy is violated, and deal with the seemingly more tractable question of how these practices would affect our sense of security if they were known to be in broad use.

That's not to say Rubenfeld's approach is without its own difficulties. For one, there's the well known problem of specifying the proper scope or level of abstraction when applying a Kantian test of generality. On one reading, after all, the principle "act only on the maxim you could will as universal law" requires us all to be farmers, because we'd all starve if everyone were (say) a journalist or law professor. How you define the rule or maxim you're generalizing makes all the difference. So should we consider the effect on security of generalizing the practice of keyword-triggered communications intercepts, or only particular keyword filters? Ditto for technologies that detect the presence of contraband: is the test whether we'd be insecure if there were scanners for heroin and explosives at every metro station, or do we inquire more broadly about the effects of deploying technologies that scan for anything Congress defines as contraband?

A second difficulty is that Rubenfeld wants to claim his approach is more objective than a standard that relies on nebulous social expectations or judicial gut-checks disguised as "balancing tests." It may well be, but it imports a different sort of subjectivity, since "security," if it's going to do the work he demands of it, needs to be seen as a partly psychological phenomenon. Rubenfeld touches on this when he considers whether the very secrecy of the NSA wiretap program counts in his favor, since a program unknown to the public can't have a chilling effect on behavior. His response is to go meta, suggesting that secrecy actually reduces security, because if and when such programs are disclosed, we tend to fear that we are being spied on in other unknown ways. That's surely true, though it seems to get the right answer for the wrong reason—if only the government were better at keeping secrets!

I can think of a couple alternative ways of dealing with that problem—an appeal to the publicity requirements of policy in a democratic society over the long term, on the one hand, and a structural argument that looks to the objective aspect of security by considering the institutional effects of secret government information collection, on the other. But the broader problem remains: security here is still significantly a function of how people feel about a particular kind of search or surveillance. That, no less than the received view, seems highly sensitive to changing norms about privacy.

These quibbles notwithstanding, however, Rubenfeld has given us a fresh and fruitful new way of looking at a core constitutional right—one that deserves to be applied to the inevitable puzzles new search technologies will present.