What is a search? Two conceptual flaws in Fourth Amendment doctrine and some hints of a remedy.

• Author: Colb, Sherry F.

INTRODUCTION I. THE BASICALLY SOUND CONCEPT OF "KNOWING EXPOSURE" II. MOVE ONE: EQUATING RISK AND INVITATION A. Trash B. "Open Fields" C. Flight D. Tracking Devices E. Electronic Eyes and Privacy in Public F. Pretend Friends III. "KNOWING EXPOSURE" AND CONSENT A. Strick Liability Crime B. "Knowing Exposure" and Strict Liability Crime C. "Knowing Exposure" and Consent D. Pretend Friends and the Breakdown of the Consent/Knowing Exposure Distinction IV. MOVE TWO: EQUATING SMALL AND LARGE INTRUSIONS A. Garbage B. Telephone and Bank Records INTRODUCTION

The Fourth Amendment protects "[t]he right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures." (1) Ushering in modern Fourth Amendment doctrine, the Supreme Court held in Katz v. United States that when a person enters a telephone booth, shuts the door, and makes a call, government agents may not record the conversation that follows without a warrant. (2) The Court noted, moreover, that the physical presence of the recording device on the outside of the telephone booth does not diminish the illegality of the taping. (3) As the concurring opinion and later decisions affirmed, the Fourth Amendment gives individuals a "reasonable expectation of privacy" in such telephone conversations. (4) People accordingly have a right to expect that, absent probable cause and a warrant, no uninvited listeners will have access to them. (5)

The decision in Katz continues to regulate the extent of lawful government investigations. As numerous scholars have observed, however, the decisions that followed Katz very narrowly defined the scope of protected privacy, such that much of the universe of investigative activity does not even trigger the Fourth Amendment's reasonableness requirements. (6) Commentators have argued persuasively that the Court's motivation for these decisions has been the link between judicially acknowledging a violation of Fourth Amendment privacy and suppressing reliable, incriminating evidence. (7) In other words, because a holding that the Fourth Amendment applies in a particular case might free a guilty defendant, courts are tempted to find no Fourth Amendment application. Though this hypothesis might causally explain why the Court has been motivated to reduce the scope of Fourth Amendment privacy, however, it does not tell us how the Court has gone about doing so, from a doctrinal, analytic perspective.

To answer the how question, this Article looks to the logical "moves" that unify almost all of the Court's cases defining the meaning of a Fourth Amendment "search." These moves have steadily eroded privacy in specific cases, and conceptually promise to eliminate it altogether, because they do not admit of any logical stopping point. The Court has therefore brought itself to a doctrinal position that is untenable, even for the most tough-on-crime Justices. In some recent decisions that recognize and leave open the possibility of broader Fourth Amendment protection, the Court displays ambivalence about the moves it has repeatedly employed and thereby calls into question the logical moves and doctrinal conclusions embraced by the earlier precedents. Unfortunately, both the moves and their occasional disavowal occur beneath the surface, rendering the doctrine, and privacy itself, unstable.

When determining what privacy the Fourth Amendment does and does not protect--what circumstances, in other words, give rise to a "reasonable expectation of privacy"--the Court asks: "What is a search?" To rule out activities that do not qualify, the Court denies privacy in whatever people "knowingly expose" to the public. (8) If a person knowingly exposes some object or activity to the public, there has accordingly been no search. (9) Absent a search, police may observe the thing that is "exposed" without having to obtain a warrant or otherwise justify their observations. "Probable cause," warrants, "reasonable suspicion," and other measures of Fourth Amendment reasonableness do not come into play unless there has been a search.

In developing the category of things that are "knowingly exposed," and therefore not a search, the Court has repeatedly made two analytic moves that effectively rob the category of any firm boundaries: (1) It treats the risk of exposure through third-party wrongdoing as tantamount to an invitation for that exposure ("Move One"); and (2) it treats exposure to a limited audience as morally equivalent to exposure to the whole world ("Move Two").

Treating risk-taking as inviting exposure effectively excuses (and even justifies) what would otherwise be wrongful conduct by third parties, including the police. If a man lies down and falls into a deep sleep on a subway train, for example, he risks having his pocket picked. A pickpocket can easily swipe the sleeping man's wallet without encountering any resistance. We might even say colloquially that the sleeping man has "asked to have his pocket picked." This colloquialism does not, however, describe a legal justification for the pickpocket. We would not say, in other words, that the man on the train has willingly agreed to the taking of his wallet (as we would, for example, if he had abandoned the wallet in the street). Like taking candy from a baby, taking a wallet from a sleeping man remains a crime, no matter how easy it is to accomplish.

The second of the two moves, treating exposure to a limited audience as identical to exposure to the world, means failing to recognize degrees of privacy in the Fourth Amendment context. A person going on vacation, for example, might give a neighbor the key to her house and ask him to water her plants while she is gone. The neighbor now has explicit permission to observe what would otherwise be hidden from view, namely, the inside of the vacationer's home (at least those pans visible from areas through which he must travel to reach the plants). By granting this permission, the vacationer has forfeited a measure of privacy and has thus knowingly exposed part of her home to her neighbor. Still, if the neighbor were to invite his friends or family into the apartment to see the vacationer's personal items, even just those things visible from where the plants are located, that act would go beyond the scope of the vacationer's permission and therefore represent an invasion of her privacy. (10) There are degrees of privacy and, accordingly, degrees of exposure, and one might choose to forfeit some of her freedom from exposure without thereby forfeiting all of it.

This Article contends that since Katz was decided, the Court--in giving content to the "knowing exposure" that separates what is protected by Fourth Amendment privacy from what is not--has made frequent use of the two moves, equating risk-taking with inviting exposure and equating limited-audience with whole-world self-exposure. This Article claims that therefore, to address the instability and poverty of Fourth Amendment doctrine, the Court must extricate these moves from its repertoire and replace them with an honest inquiry into whether police have acted in a manner that exposes what would have remained hidden absent the transgression of a legal or social norm. This inquiry would adhere to the doctrinal foundations of privacy as articulated in Katz.

In the process of explicating and critiquing the Court's two analytic moves, this Article argues that the notion of "knowing exposure" ought to (and does, in its definition) resemble the idea of "consent" to a search. (11) Recognizing a common definition for these two concepts would yield beneficial results. First, it would represent an open acknowledgement that "knowing exposure" only occurs when there has been some explicit or tacit consent to public observation, and not simply the taking of a risk or the limited exposure of what is then further disseminated. Second, the coordination of "knowing exposure" and "consent" might move the Court to reconsider its ill-advised position that one can give voluntary consent to a search without knowing that police would take "no" for an answer. (12) Finally, through a close analysis of several recent cases, including Kyllo v. United States, (13) Ferguson v. City of Charleston, (14) and Minnesota v. Carter, (15) this Article identifies and discusses the Court's own discomfort with the two logical moves it has embraced for dealing with the question of what qualifies as a Fourth Amendment search. These cases leave open the possibility that norm transgression will come to replace the flawed moves of "risk as invitation" and "partial exposure as total exposure" in defining the scope of Fourth Amendment privacy.

1. THE BASICALLY SOUND CONCEPT OF "KNOWING EXPOSURE"

   The Supreme Court has consistently held that some governmental activities do not qualify as searches and thus do not trigger the Fourth Amendment's requirement that they be reasonable. The word "searches" appears in the text of the Fourth Amendment as the subject matter to be regulated, but "search" is not a self-defining term. As a result, one's view of police investigative power will inevitably shape one's interpretation of that term. Decisions about which police activity to place entirely outside the scope of the Fourth Amendment, for example, will rest on normative choices. Indeed, the Court has acknowledged the relationship between social norms and Fourth Amendment law by defining a search as the invasion of a "reasonable expectation of privacy" and by explicitly proposing that a person's subjective expectation of privacy implicates the Fourth Amendment only if the "expectation of privacy is `legitimate in the sense required by the Fourth Amendment,' ... [which] turns on `whether the government's intrusion infringes upon the personal and societal values protected by the Fourth Amendment.'" (16) Social norms are therefore at the heart of the Court's approach to designating those expectations of...