TABLE OF CONTENTS INTRODUCTION I. THE FOURTH AMENDMENT AND THE DEFERENCE NORM IN NEW TECHNOLOGIES A. Property Law and the Fourth Amendment B. Katz v. United States and the Property-Based View C. The Deference Norm in New Technologies D. Property-Defeating Surveillance Technologies: Knotts, Karo, and Kyllo E. Why the Fourth Amendment Alone Cannot Protect Privacy in New Technologies II. WIRETAPPING LAW AND LEGISLATIVE REGULATION OF GOVERNMENT INVESTIGATIONS INVOLVING NEW TECHNOLOGIES A. The Origins of Wiretapping Law: Prohibition, Early Statutory Protections, and the Olmstead Case B. 1934-1967: From the Communications Act to Berger and Katz C. 1967 and 1968: Berger, Katz, and Title III D. Wiretapping After Title III: Constitutional in Theory, Statutory in Fact E. Privacy in New Technologies and the Statutory Norm III. INSTITUTIONAL COMPETENCE AND REGULATION OF GOVERNMENT INVESTIGATIONS INVOLVING NEW TECHNOLOGIES A. Judicial Creation of Investigative Rules When Facts Are Stable B. The Fluctuating Relationship Between Surveillance and Privacy in Developing Technologies C. The Challenge of Ex Post Decisionmaking D. The Need for Flexibility in Light of Changing Facts E. The Judicial Information Deficit F. The Uniqueness of Criminal Procedure: A Response to Professors Lessig and Sherry, and the Public Choice Theorists CONCLUSION INTRODUCTION
The Supreme Court recently considered whether aiming an infrared thermal imaging device at a suspect's home can violate the Fourth Amendment. Kyllo v. United States (1) announced a new and comprehensive rule: the government's warrantless use of sense-enhancing technology that is "not in general use" violates the Fourth Amendment when it yields "details of the home that would previously have been unknowable without physical intrusion." (2) Justice Scalia's majority opinion acknowledged that the Court's rule was not needed to resolve the case before it, which dealt only with a crude infrared camera. (3) Justice Scalia justified the broad rule on the Court's need to "take the long view" (4) and protect the public from the threat of other more nefarious government surveillance technologies--including technologies yet to be invented. (5)
As surprising as Kyllo's authorship may be, (6) the opinion captures the prevailing zeitgeist about law, technology, and privacy. When technology threatens privacy, the thinking goes, the courts and the Constitution should offer the primary response. While Congress and state legislatures may have a limited role regulating government investigations involving new technologies, the real work must be done by judicial interpretations of the Fourth Amendment. (7) The courts come first, legislatures a distant second. Justice Brandeis's famous dissent in Olmstead v. United States (8) provides the guiding light. Brandeis urged in 1928 that to protect our liberties as technology advances, "every unjustifiable intrusion by the Government upon the privacy of the individual, whatever the means employed, must be deemed a violation of the Fourth Amendment." (9) Seventy-five years later, modern commentators echo this approach with surprising uniformity. The view that the Fourth Amendment should be interpreted broadly in response to technological change has been embraced by leading theorists of law and technology such as Lawrence Lessig, (10) leading constitutional law figures such as Laurence Tribe, (11) and nearly everyone else who has written on the intersection of technology and criminal procedure. (12) Because of its broad support among leading commentators, I will label this approach the popular view of the Fourth Amendment and new technologies.
Although the popular view has been justified on many different grounds, most expressions of it tend to rest on one or more of three complementary premises. The first premise is doctrinal, the second is historical, and the third is functional. The doctrinal premise is that the courts should actively monitor technology's effects on privacy because Fourth Amendment doctrine demands it. The "reasonable expectation of privacy" test governs Fourth Amendment law, (13) and it is up to the courts to determine when an expectation of privacy is "reasonable." (14) As a result, the courts must update and redefine the Fourth Amendment as technology evolves, creating and recreating reasonable rules that effectively regulate law enforcement and protect privacy in new technologies. The historical premise suggests that the courts should play an active role in the regulation of new technologies because they have done so successfully in the past. (15) In particular, the Supreme Court's reversal of Olmstead and recognition of Fourth Amendment protections against government wiretapping in Katz v. United States (16) establish a precedent that supports future intervention. The third and final premise justifies a strong judicial role for reasons of institutional competence. Courts should take the lead crafting rules to protect privacy because courts are well-situated to regulate criminal investigations involving new technologies, (17) Taken together, these three arguments suggest that courts must, have, and should use the Fourth Amendment to provide the first line of defense against government invasions of privacy allowed by new technologies.
This article challenges the popular view of the role of the Fourth Amendment in new technologies. I will argue that the popular vision is based on a romantic but somewhat inaccurate view of Fourth Amendment doctrine, history, and function. Properly understood, considerations of doctrine, history, and function tend to counsel against an aggressive judicial role in the application of the Fourth Amendment to developing technologies. They teach that courts should place a thumb on the scale in favor of judicial caution when technology is in flux, and should consider allowing legislatures to provide the primary rules governing law enforcement investigations involving new technologies. While proponents of the popular view assume that the Fourth Amendment can play the same central role regulating government use of developing technologies that it has played in more traditional cases, there are sound reasons to treat developing technologies differently. These differences suggest that statutory rules rather than constitutional rules should provide the primary source of privacy protections regulating law-enforcement use of rapidly developing technologies. When technology is in flux, Fourth Amendment protections should remain relatively modest until the technology stabilizes.
This article aims to reorient current thinking about how the legal system should regulate criminal investigations involving new technologies. I want to nudge us away from thinking primarily in terms of the Fourth Amendment, and focus attention instead on legislative rules. I contend that the legislative branch rather than the judiciary should create the primary investigative rules when technology is changing. Contrary to the three premises underlying the popular view, legislative predominance in the face of developing technologies is consistent with current Fourth Amendment doctrine, accurately reflects historical practice, and is likely to continue in the future given the relative institutional competence of courts and legislatures. The institutional advantages of legislative rule making may eventually create a bifurcated privacy regime in which the governing law is primarily constitutional in most areas, but primarily statutory in areas of technological flux. Technological change may reveal the institutional limits of the modern enterprise of constitutional criminal procedure, exposing the need for statutory guidance when technology is changing rapidly. The implications for the field of criminal procedure are considerable. If criminal prosecutions involving new technologies continue to grow in number and importance, a basic understanding of criminal procedure rules may someday require as much knowledge of the United States Code as the United States Reports.
By arguing in favor of judicial caution, I don't wish to suggest that privacy in unimportant. To the contrary: privacy is one of our most cherished values, and rules that effectively regulate criminal investigations to prevent government abuse are essential to our traditions. At the same time, it is wrong to assume that courts necessarily generate more protective rules than legislatures. In recent decades, legislative privacy rules governing new technologies have proven roughly as privacy protective as, and quite often more protective than, parallel Fourth Amendment rules. Judicial deference has often invited Congressional regulation. As a result, the key question is less how much criminal procedure rules should protect privacy than whether we should look primarily to the courts or to Congress to generate those rules. I believe that we should look first to Congress when technology is changing rapidly. A renewed focus on the possibilities offered by legislative rules will enable the legal system to generate better rules--rules that are more nuanced, clear, and that optimize the critical balance between privacy and public safety more effectively when technology is in flux.
I will develop my argument in three parts. Each part challenges one of the premises supporting the popular view, and tells a cautionary tale about the limits of the Fourth Amendment when technology is in flux. Part I challenges the doctrinal premise that Fourth Amendment doctrine requires the courts to assume an active role that can adequately protect privacy in new technologies. I argue that existing Fourth Amendment doctrine generally counsels in favor of caution in cases involving new technologies. The Katz "reasonable expectation of privacy" test has proven more a revolution on paper than in practice; Katz has had a surprisingly limited effect on the largely property-based contours of traditional Fourth...