Introduction: Public ... Privacy? The Fourth Amendment before Privacy The "Privacies of Life"--Boyd v. United States Trespass versus Dignity--Olmstead v. United States Public View--United States v. Lee The Tortured Life of the "Trespass Rule" The "Privacy" Amendment--Katz v. United States The Reasonable Expectation of Privacy: Decoupling Property from the Fourth Amendment Measuring Privacy as "Reasonable Expectation" Surveillance Technology and the Public/Private Boundary Privacy on Public Streets: United States v. Knotts and "Beeper" Tracking Privacy and Aerial View Open Fields: Oliver v. United States Aerial Surveillance: Ciraolo and Riley Property and the Right to Exclude Technology-Based Surveillance: Kyllo v. United States New Surveillance Technologies and the Demand for "Public Privacy" Global Positioning System Unmanned Aerial Surveillance Attempting to Define a Right to Privacy in Public Space United States v. Maynard Knotts and the Question of "Dragnet" Surveillance Actual Exposure Constructive Exposure "Mosaic Theory" and Its Implications for Surveillance Technologies United States v. Jones and the Future of the "Mosaic Theory" Criticisms of "Mosaic Theory" Knotts Controls The "Mosaic Theory" is Unworkable The Problems of the "Mosaic Theory" are Better Handled by Statute Conclusion INTRODUCTION: PUBLIC ... PRIVACY?
In an article in the Kansas Law Review, Chief Justice William Rehnquist offered a now well-known hypothetical that summarized the tension inherent in the normative concept of "privacy" and its particular manifestation in Fourth Amendment jurisprudence. (2) In his hypothetical, Chief Justice Rehnquist asks the reader to imagine a police officer standing in the parking lot of a bar from the hours of 5:30 p.m. to 7:30 p.m. every day. (3) Each day, the police officer takes notes and records the license plates of every vehicle that parks in the lot adjacent to the bar in order to identify the bar's "regulars." At this point, assume that the police officer has no particular reason to know of any unlawful conduct by the bar's patrons.
Rehnquist imagines that this type of persistent surveillance activity, conducted without suspicion of criminal wrongdoing, and done solely for the purpose of recording names for future police reference is police conduct that most persons would rightly, in his appraisal, feel uneasy about, intuiting it to be an inappropriate law enforcement function. (4) Despite the sense that people would find this type of "extreme" surveillance activity disturbing, Chief Justice Rehnquist purposely avoids labeling this disturbed sensibility as "privacy." (5) For him, "there can be no question that driving an automobile down a public street and into a parking lot of a bar, which is itself open to the general public, is not in any normal sense of the word a 'private' act." (6) Instead, as any member of the general public is free to engage in the same observational conduct attributed to the police in this hypothetical, this uneasiness is merely a sense that unwarranted, persistent surveillance is not a proper governmental function. (7) For the Chief Justice, the ability or inability to exclude observation of one's conduct--call it secrecy (8)--is the touchstone of constitutionally cognizable "privacy."
Chief Justice Rehnquist described these facts as "extreme," (9) which is correct in that it would be unusual in the United States for a law enforcement officer to engage in prolonged visual surveillance simply for the sake of collecting volumes of information on persons not suspected of any wrongdoing. However, in a more modern sense, this hypothetical is no longer so extreme. (10) Replacing the formerly necessary beat-cop with technologically-enhanced surveillance systems makes the execution of persistent government observation in public spaces more covert and less costly. (11) Because of the heightened surveillance capabilities created through technological advancement, the Chief Justice's then-hypothetical problem seems far less hypothetical today. Specifically, in a post-9/11 world, where government agencies have undergone a clear tactical shift from post-crime investigation to a mode of preventative detection, government demand continues to push development in the field of surveillance technologies. (12) This has had the effect of not only making technology more operationally efficient--"better" in a purely abstract sense--but also increasing its supply, decreasing cost, and therefore, broadening the market of users. (13)
As a result, it is not only the most well-funded federal and international law enforcement, military, and intelligence agencies that have access to top-line surveillance technologies, but also state and local law enforcement. (14) The convergence of these and other factors--changed mission demands, improved technologies, increased cost efficiency, and a constrained fiscal environment--substantially shifts many of the assumptions underlying the Fourth Amendment's jurisprudence, (15) especially as to the freedoms a person may possess outside of his or home. Where society might have once been able to depend on technology's cost to act as a self-regulating tool, that assumption has since been turned on its head. As market forces no longer exert de facto regulatory force over the widespread employment of surveillance technologies, it may now be necessary to assess the need for greater positive control through de jure regulatory mechanisms. Assuming that a policy response is necessary in light of these dynamic forces, the question then is what form and through which branch of government should any regulatory action emanate?
In order to answer that question, it is necessary to isolate what "sensibility" or "right" would be lost as a result of enhanced technological surveillance of public space. At its philosophical core, the hypothetical posed by Chief Justice Rehnquist and the not-so-hypothetical modern manifestation of it suggests that there is, at some intuitive level, a normative belief that one should be free from persistent visual observation--even when in public. However, despite the predictable unease that would be felt by any person being observed in public, the Fourth Amendment--even as the Constitution's "core" privacy right, (16) would almost as predictably, not prevent the government from engaging in such surveillance practices--as the constitutionally assigned plain meaning of "privacy" excludes that "which is itself open to the general public." (17) The source of the tension, then, is that the social norm proposed by the Chief Justice--that persons, even though present in public space, should not be subject to persistent, warrantless observation--seems intuitively correct. (18)
The U.S. Supreme Court, the traditional protector of the public's right to "privacy," (19) has historically had few, if any, satisfying responses to a public looking for protection from the dangers of a surveillance state. Whether it has been the use of beepers to track surveillance targets, (20) or police over-flights of private property, (21) the Court has historically held that these actions are not searches; therefore, they do not require warrants, because no definition of "privacy" in the constitutional sense could inure to a person when he or she exposes their conduct to public view. (22) Even when enhanced by technology, the philosophical question remains the same--how can someone reasonably expect to enjoy a sense of privacy even when in public?