THE QUALITATIVE FOURTH AMENDMENT: THE CASE FOR A REFINED, INFORMATION-FOCUSED APPROACH TO FOURTH AMENDMENT CASES INVOLVING NONTRESPASSORY GOVERNMENT SURVEILLANCE.

• Author: Wagner, Joshua L.

TABLE OF CONTENTS INTRODUCTION 1728 I. THE RELEVANT HISTORY OF FOURTH AMENDMENT DOCTRINE 1731 A. Katz and the "Reasonable Expectation of Privacy" 1732 B. Ciraolo, Riley, and Public Exposure 1733 C. Recent Cases Involving Modern Technology 1735 D. Carpenter v. United States in Context 1737 1. The Facts of the Case 1738 2. The Court's Holding 1739 II. FINDING A THROUGH LINE IN FOURTH AMENDMENT DOCTRINE 1741 A. The Many Unsatisfactory Candidates 1742 B. An Effective Information-Based Approach 1747 1. The Obtainable Information Approach as a Through Line 1747 for Post-Katz Fourth Amendment Cases 2. The Information-Based Approach as a Roadmap for the 1749 Future a. The Continuing Relevance of the Trespass 1750 Qualification b. Defining "Surveillance Technology" 1750 III. THE THORNY THIRD-PARTY DOCTRINE 1753 A. The Smith-Miller Standard 1754 B. Carpenter and Third-Party Doctrine 1756 C. Third-Party Doctrine and the Obtainable Information 1758 Standard CONCLUSION 1760 INTRODUCTION

In his 2001 majority opinion for Kyllo u. United States, Justice Scalia adopted his characteristic chiding tone to gently reproach what he saw as a notably liberal departure from the original textual interpretation of the Constitution. (1) The Katz test for Fourth Amendment violations. (2) to Scalia. was plainly "circular, and hence subjective and unpredictable."' (3) That it was one of the most influential and oft-discussed decisions the Supreme Court has ever handed down (4) made little difference; regardless of whatever Justice Harlan and his successors had said, the Fourth Amendment was. at its heart, a protection against government interference with property and had never been tied to "the quality or quantity of information obtained." (5)

Of course. Scalia's property-centric reproach of Katz's legacy was far from unprecedented. In fact, legal scholars as well respected as Judge Richard Posner of the Seventh Circuit Court of Appeals had been slinging the very same criticisms at the two-prong Katz test for years. (6) No matter one's opinion of either of these jurists, or of the ubiquitous "reasonable expectation of privacy" (7) test, it would be difficult to argue that it has been easy to apply in practice. And the Court has, frustratingly, avoided directly addressing the issue. (8) Given this, one might be tempted to join the textualists in their opinion that the old, easy-to-apply, property-based standard is superior.

That does not mean, however, that the Katz test has led to undesirable outcomes. In the age of modern technology, when the government has access to surveillance methods allowing unprecedented intrusion into the privacies of life, (9) Americans are more conscious of their privacy interests than ever and less confident that those interests will be protected. (10) For all the valid criticisms that may be levied against it, the Katz test, at the very least, offers an avenue for confronting these concerns.

This is exactly what happened when the Court rendered its decision in Carpenter v. United States, a landmark case extending Fourth Amendment protection to historical cell site location information (CSLI)--data generated, collected, and maintained by cell phone service providers entirely outside the control of the individuals the data describes. (11) Reactions to Carpenter varied, (12) but it should be clear to anyone who understands the history and context behind the Court's decision that it represents a direct repudiation of the notion that the appropriate Fourth Amendment analysis is not "tied to measurement of the quality or quantity of information obtained." (13) In fact, the Carpenter analysis was explicitly tied to both the quantity and quality of the information at stake. (14)

But the problem remains unaddressed, as the Court has yet to outline an all-encompassing approach to Fourth Amendment cases of unwarranted government surveillance that do not involve physical trespass. (15) These kinds of cases rarely overrule each other, so it seems intuitive that the Court should be able to establish some consistent through line. Yet, so far, it has not. This Note proposes that it can be done, but only if the Court readily admits that the Fourth Amendment no longer protects only property, but also information. The ultimate outcome of Carpenter, and of every case that has adequately applied the Katz test, has been to keep certain information out of government hands.

Somewhat ironically, this includes Kyllo. It is from the language of Kyllo, originally intended to protect the traditionally privileged space of the home, (16) that this Note draws inspiration for its proposed rule: absent probable cause, the Fourth Amendment proscribes the government from obtaining information that could not otherwise have been obtained without resorting to surveillance technology or physically trespassing on private property. This relatively simple standard, which can be called the obtainable information rule, unifies the collective holdings of post-Katz surveillance cases and provides a flexible framework for future decisions and new technologies.

In order to understand exactly how the obtainable information standard works, it is important to place it in the historical context of Fourth Amendment doctrine. Part I of this Note will examine the history of Fourth Amendment doctrine in cases of government surveillance since 1967 and leading up to Carpenter v. United States, a landmark case of critical importance to this argument. Part II will explore some of the theories proposed by academics for reconstructing, clarifying, or otherwise refining Fourth Amendment surveillance doctrine in a palatable manner, and will explain why each is unsatisfactory in at least one regard. It will then formally propose the obtainable information standard as a satisfactory alternative, capable of unifying post-Katz surveillance jurisprudence under a single theory. Fart III will discuss the intersection between the obtainable information standard and third-party doctrine, which has become a subject of much discussion (and concern) following Carpenter. It will explain how the third-party doctrine need not be thrown out the window in order to accommodate the proposed standard.

Finally, it is worth noting that the purpose of this Note is not to argue that the obtainable information rule is the solution most resonant with the original meaning of the Fourth Amendment. Rather, the primary purpose of the rule is to synthesize the various holdings of the Supreme Court since Katz into a single, easy-to-apply standard. As Part II will explain, there is also good reason to believe that it is the most functionally desirable rule, but this Note does not address the contention that any or all of the Supreme Court's holdings since Katz were themselves unconstitutional and should be overruled.

1. THE RELEVANT HISTORY OF FOURTH AMENDMENT DOCTRINE

   In the first half of the twentieth century, the Supreme Court had consistently taken a physical property-based approach to assessing Fourth Amendment claims. (1)' Perhaps the most notable example of this approach was Chief Justice Taft's declaration in Olmstead v. United States that the Fourth Amendment should be construed narrowly enough to apply only to "material things--the person, the house, his papers or his effects." (18) The Taft Court ultimately held that warrantless wiretapping did not violate the Fourth Amendment, as there was no actual physical entry of the defendant's house or seizure of his belongings. (19) Following Olmstead, the Court continued to apply this narrow construction of the Fourth Amendment, finding violations only when the government had physically intruded upon a defendant's property. (20)

   1. Katz and the "Reasonable Expectation of Privacy"

      Then, in 1967. the Court dramatically expanded the realm of Fourth Amendment doctrine with its opinion in Katz v. United States. (21) Charles Katz was convicted of transmitting wagering information via telephone based on evidence gathered from warrantless FBI recordings of his phone conversations. (22) The district and appeals courts quickly rejected his Fourth Amendment claims because the agents never actually intruded on any property Katz owned. (23) However, in a landmark decision, the Supreme Court overruled Olmstead, rejecting the constitutional requirement of physical trespass or seizure. (24) Moreover, the Court took a step further and declared that "the Fourth Amendment protects people, not places," (25) effectively ending the era of the property-based approach. (26)

      The majority opinion in Katz offered no clear standard for courts to utilize when assessing Fourth Amendment claims, but Justice Harlan's concurring opinion proposed a two-step test: (1) that the defendant exhibited a subjective expectation of privacy, and (2) that the expectation is "one that society is prepared to recognize as reasonable." (27) Twelve years later, in Smith u. Maryland, a majority of the Court adopted Harlan's "reasonable expectation" test, and a new era of Fourth Amendment jurisprudence was born. (28)

      All was not said and done, however. Katz's new interpretation of the rights protected against unreasonable search and seizure created a slew of new questions, especially as technology continued to rapidly advance near the beginning of the twenty-first century. Foreseeing the danger that advancing technology poses to sources of constitutionally protected private activity, the Supreme Court chose to sharpen the focus of Katz while simultaneously reintroducing a traditional spatial context to the analysis. (29)

   2. Ciraolo, Riley, and Public Exposure

      A key qualification of the Court's opinion in Katz was the idea of public exposure: anything that has been "knowingly expose[d] to the public" cannot reasonably be expected to be kept private. (30) This would seem self-evident and perhaps more relevant to the first prong of the Katz test. After all, if Charles Katz had shouted the...