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Article Excerpt
I. INTRODUCTION
In both the United States and Canada, the reasonable expectation of privacy test defines the scope of constitutional protection from governmental privacy intrusions. When a court decides that a person has no reasonable expectation of privacy in relation to an investigative technique, there is no "search" or "seizure" within the meaning of the Fourth Amendment of the United States Constitution (1) or [section] 8 of the Canadian Charter of Rights and Freedoms. (2) In such cases, police are free (absent any statutory restriction) to use the technique without first obtaining a warrant or establishing individualized suspicion. (3) When there is a reasonable expectation of privacy, in contrast, police must generally obtain a warrant based on probable cause before conducting the search. (4)
Unfortunately, the jurisprudence that American and Canadian courts have developed in applying the reasonable expectation of privacy test is notoriously circular, imprecise, and unpredictable. (5) In this Article, I argue that this indeterminacy stems in large measure from the tendency of judges to think of privacy in non-instrumentalist terms. Courts typically view privacy as a fundamental right, rooted in notions of dignity, autonomy, identity, personality, or liberty. (6) And while they often acknowledge the existence of countervailing interests, they generally treat privacy as an unalloyed social good. (7)
There are several problems with this approach, which I refer to as the "moral" conception of privacy. First, casting privacy as a moral right is normatively questionable. (8) It is not at all clear that privacy is as central to human flourishing as most deontologically-oriented jurists claim.(9) Second, to the extent that it is important, the moral approach does a poor job of identifying the circumstances in which privacy should prevail over countervailing interests, such as the deterrence of crime. Third, neither the Fourth Amendment nor [section] 8 of the Charter protects privacy in a "fundamental" manner; they protect only the right to be free from "unreasonable" searches and seizures. (10) Even gross privacy invasions may be justified when the State can show that they are likely to reveal evidence of serious crimes. (11) As courts in both countries have recognized, constitutional search and seizure decisions (including threshold reasonable expectation of privacy determinations) call for some kind of instrumentalist cost-benefit calculation. (12) Yet by conceptualizing privacy in moral terms, courts have largely failed to perform this calculation with rigor, clarity, or transparency.
The intent of this Article, then, is to develop a fully instrumentalist approach to the reasonable expectation of privacy test. The obvious place to start is economic analysis. There is a flourishing literature on the law and economics of privacy. Drawing mostly from the economics of information, (13) legal economists have taken on a wide variety of privacy issues. (14) There have been few attempts, however, to apply economic insights to search and seizure law. (15) This Article aims to help fill this gap. I provide an accounting of the costs and benefits of governmental privacy intrusions and propose a framework for making reasonable expectation of privacy decisions that maximize social welfare.
In contrast to the prevailing moral approach, which treats privacy as a fundamental right, the economic approach views it as a normatively neutral aspect of self-interest: the desire to conceal and control potentially damaging personal information. In this view, privacy should not be protected when its primary effect is to impede the optimal deterrence of crime. However, in other cases legal protections against governmental surveillance may enhance social welfare by encouraging productive transactions, diminishing the costs of non-legal privacy barriers, and limiting suboptimal policing practices such as discriminatory profiling and the enforcement of inefficient criminal prohibitions. Economics and public choice theory can also help to minimize decision-making error by predicting which legal actors--police, legislatures, or courts--are best placed to make optimal trade-offs between privacy and crime control.
The Article proceeds as follows. In Section II, I briefly describe the American and Canadian Supreme Courts' reasonable expectation of privacy doctrines and highlight their chief inadequacy: the indeterminacy of the "public exposure" and "intimacy" doctrines that the Courts have used to decide whether to regulate novel search technologies. Section III outlines the economic approach to the reasonable expectation of privacy test. Sections IV and V apply this approach to two novel search technologies: infrared imaging and location tracking. This analysis suggests that courts should recognize a reasonable expectation of privacy in the latter case, but not the former. Section VI concludes.
II. REASONABLE EXPECTATION OF PRIVACY DOCTRINE AND NOVEL SEARCH TECHNOLOGIES
The use of the reasonable expectation of privacy test dates from the United States Supreme Court's 1967 decision in Katz v. United States. (16) Katz famously departed from the prevailing conception of Fourth Amendment searches as physical trespasses into "constitutionally-protected" areas. (17) In deciding that the placement of an electronic listening and recording device outside a public telephone booth was a search, Justice Stewart declared for the majority that the Fourth Amendment protected "people, not places," (18) and the surreptitious interception of the petitioner's conversation "violated the privacy upon which he justifiably relied." (19) The "reasonable expectation" phraseology, however, stems from Justice Harlan's concurring opinion. Harlan stated, in language later adopted by a majority of the Court, that to be considered a search, it must be shown both that a person "exhibited an actual (subjective) expectation of privacy and ... that the expectation be one that society is prepared to recognize as 'reasonable.'" (20) In its first decision interpreting [section] 8 of the Charter, the Supreme Court of Canada adopted the same approach. (21)
How, then, have courts gone about deciding what constitutes a "reasonable expectation of privacy"? This is not the place to summarize the reams of doctrine on the question. (22) It will be helpful, however, to provide some sense of how the American and Canadian Supreme Courts have applied the test to novel search technologies.
Not surprisingly (and contrary to Justice Harlan's dictum in Katz), courts have not considered the existence of a subjective expectation of privacy to be a necessary condition of constitutional protection; (23) otherwise, police could simply advertise their intention to monitor everything capable of being monitored. (24) Moreover, people who were more suspicious or aware of governmental surveillance would receive less constitutional protection than those more trusting or ignorant. (25) The focus has instead been on the second component of Harlan's formula: whether an expectation of privacy is "reasonable."
Like other reasonableness standards, on its face, the reasonable expectation of privacy test is extremely vague. Insofar as it gauges "expectations" of privacy (both subjective and objective) in relation to prevailing social and technological conditions, it is also tautological. As Wasserstrom and Seidman have put it, "Reasonable expectations are defined by reference to a current reality that includes the very practices under attack, rather than by reference to the kinds of expectations people would have in a normatively attractive society." (26) The test's language implies that we can expect less and less constitutional protection for privacy as technology continues to enhance the power and lower the costs of surveillance. (27)
To be sure, courts have attempted to suffuse the test with normative content. (28) They have pointed out many virtues of privacy and catalogued myriad factors influencing reasonable expectation of privacy decisions. But the key conceptual tools that the courts have developed to aid these decisions--the public exposure and intimacy doctrines--have produced little jurisprudential consistency, predictability, or consensus.
A. PUBLIC EXPOSURE
The public exposure doctrine exempts from constitutional protection information voluntarily disclosed to the public. As Justice Stewart explained in Katz, "What a person knowingly exposes to the public, even in his own home or office, is not a subject of Fourth Amendment protection. But what he seeks to preserve as private, even in an area accessible to the public, may be constitutionally protected." (29) The doctrine is a natural outgrowth of liberal moral theory. If rational, autonomous agents freely choose to expose information to the public, then they cannot complain if others use that information against them.
It seems axiomatic that information voluntarily released into the public domain cannot attract a reasonable expectation of privacy. The problem, of course, is that the meanings of "voluntary" and "public" are sometimes contestable. People frequently divulge information, for example, assuming that it will be used only for certain limited purposes. (30) They may also subject themselves to observation assuming that their identities will likely remain anonymous. But what happens when technological search tools upend these assumptions? Can we still say that there has been a voluntary exposure?
Judges have given divergent answers to these questions. For example, the American and Canadian Supreme Courts have differed on the question of whether the electronic interception of speech constitutes a "search" when one of the speakers is an undercover police informant. As discussed, the United States Supreme Court established in Katz that surreptitious interceptions of private communications are Fourth Amendment searches. Soon after, however, it decided that when one of the communicators is aware of the interception, Katz does not apply. (31) In United States v. White, the Court held that if the law "gives no protection to the wrongdoer whose trusted accomplice is or becomes a police agent, neither should it protect him when that same agent has recorded or transmitted the conversations which are later offered in evidence to prove the State's case." (32)
The Supreme Court of Canada has taken a different approach. Following Katz, it has unsurprisingly ruled that the surreptitious electronic interception of private communications invades a reasonable expectation of privacy. (33) But in R. v. Duarte, it rejected the "risk analysis" of White and held that participant surveillance also constitutes a [section] 8 search. (34) Writing for the Court, Justice La Forest asserted that while [section] 8 does not protect people from the risk that their confidants will turn out to be informers, it does prohibit the State from arbitrarily making a "permanent electronic record" of their conversations. (35) The Court similarly held in R. v. Wong that surreptitious video surveillance (without audio interception) invades a reasonable expectation of privacy. (36)
Similar differences have arisen over whether it invades a reasonable expectation of privacy to follow a suspect's vehicle over public roads using a surreptitiously-planted, radio-frequency tracking device. In United States v. Knotts, the United States Supreme Court held that it did not. (37) This type of surveillance, the Court reasoned, revealed no more information than could have been obtained through visual surveillance of the vehicle from public vantage points. "Nothing in the Fourth Amendment," then-Justice Rehnquist wrote, "prohibited the police from augmenting the sensory faculties bestowed upon them at birth with such enhancement as science and technology afforded them...." (38) In United States v. Karo, however, the Court decided that the Fourth Amendment is engaged when beepers are used to track items within private residences. (39) Unlike in Knotts, the Court noted, the beeper in Karo was used "to obtain information that it could not have obtained by observation from outside the curtilage of the house." (40)
Though it seemed reluctant to do so, the Supreme Court of Canada concluded in R. v. Wise that the use of a beeper to monitor a vehicle on public roads invaded a reasonable expectation of privacy. (41) The Court declared, however, that the invasion of privacy was minimal. (42) "This particular beeper," the majority stated, "was a very rudimentary extension of physical surveillance." (43)
There has also been disagreement on whether a reasonable expectation of privacy exists in relation to the non-content "envelope" information accompanying electronic communications. (44) In Smith v. Maryland, the United States Supreme Court ruled that the installation and use of a "pen register," which records the numbers dialed from a telephone, did not invade a reasonable expectation of privacy. (45) The Court noted that the register did not record the content of conversations and suggested that people are aware that the numbers they dial may be recorded for commercial and law enforcement purposes. (46) In any event, it concluded, any expectation of privacy was not reasonable, as a person has "no legitimate expectation of privacy in information he voluntarily turns over to third parties." (47) In Canada, in contrast, several lower courts have found that people have a reasonable expectation of privacy with respect to telephone envelope information, so warrants to seize it must be based on probable cause. (48)
B. INTIMACY
As its name suggests, the intimacy doctrine holds that searches revealing sensitive personal information are more likely to trigger a reasonable expectation of privacy than those uncovering only mundane information. Like the public exposure doctrine, the intimacy doctrine is intuitively appealing. (49) People are less concerned about disclosing routine details of their daily lives than potentially stigmatizing information, such as views or activities relating to sexuality, politics, or religion. And like the public exposure doctrine, the intimacy doctrine derives from liberal moral philosophy. For liberal privacy theorists, intimate information is more central to autonomy, identity, and personality than non-intimate information. (50)
But as legal economists have pointed out, intimate information is not self-evidently deserving of legal protection. (51) Under competitive conditions, there is no reason to protect one party's ability to conceal private information. In voluntary transactions (whether economic or social), the parties' preferences for knowledge and privacy should generate the disclosure of the efficient amount of information. (52) Granting legal protection for the concealment of discreditable (but truthful) information is inefficient because it increases the cost of productive transactions. If it is inefficient to protect sellers' ability to misrepresent the quality of their goods, then it is equally inefficient to protect people's ability to misrepresent their character to others. (53) By limiting our ability to discern others' characters, trustworthiness, and other attributes, privacy either increases the cost of or deters productive economic and social interactions.
It is inappropriate, some might argue, to analogize the state's attempt to obtain personal information to the sale of goods between private parties. But the case for protecting intimate, private information from governmental scrutiny rests on the same ground as in private transactions. While the capacity of government to cause harm by collecting personal information is great, so is the people's capacity to cause harm by concealing it. More crime is the inevitable consequence of inhibiting the government's ability to uncover discreditable, private information. However, as discussed in detail below, allowing police to obtain personal information by certain means may sometimes generate suboptimal outcomes; for example, unrestricted wiretapping might inhibit communication or induce wasteful spending on measures to protect privacy. In such cases, it may be efficient to regulate investigative methods that invade privacy. This suggests that in determining the constitutionality of a novel search technique, courts should focus on the methods used by police rather than the nature of the information those methods reveal. In most cases, this is precisely what the law does. When police can demonstrate sufficient grounds for suspicion, they are permitted to collect highly intimate information. (54)
Of course, courts use the reasonable expectation of privacy test to determine whether police can search in the absence of such a demonstration. In such cases, it could be argued that gauging the intimacy of the information revealed by a search technique helps predict whether regulating the technique would prevent inefficient behavioral responses.
In practice, however, measuring the inherent intimacy of information has proven to be exceedingly difficult. Courts have come to varying conclusions, for example, on the question of whether a reasonable expectation of privacy is invaded when information normally contained in constitutionally protected areas (such as residences, vehicles, or luggage) is extracted by "sense-enhancing" technologies. Before and after Katz, the United States Supreme Court ruled that the use of flashlights and telescopic lenses does not constitute a Fourth Amendment search. (55) In California v. Ciraolo, the Court came to the same conclusion with respect to the visual observation of property from the air (with either the untrained eye or cameras), so long as the airspace is "public[ly] navigable," and the search is "in a physically nonintrusive manner." (56) The Ciraolo Court reasoned that activities that are "clearly visible" from a "public vantage point" are not protected by the Fourth Amendment. (57) It warned, however, that it might decide differently where observations are made with "modern technology which discloses to the senses those intimate associations, objects or activities otherwise imperceptible to police or fellow citizens" (58) or "highly sophisticated surveillance equipment not generally available to the public, such as satellite technology." (59)
The Court heeded this warning in Kyllo v. United States, where a narrow majority ruled that the police violated the Fourth Amendment by using an infrared camera to detect heat radiating from a residential marijuana growing operation, despite the fact that the device was not physically penetrating and showed only crude images of relatively warmer and cooler areas. (60) "[O]btaining by sense-enhancing technology any information regarding the interior of the home that could not otherwise have been obtained without physical 'intrusion into a constitutionally protected area,'" Justice Scalia wrote, "constitutes a search--at least where (as here) the technology in question is not in general public use." (61) The Court came to a different conclusion in two cases where police used drug sniffing dogs to detect narcotics concealed in airport luggage (62) and the trunk of a vehicle. (63) Such searches are relatively non-intrusive, the Court concluded, and reveal no information other than the presence of contraband. (64)
The Supreme Court of Canada has not yet dealt with either visual aerial surveillance or drug sniffing dogs. Lower courts, however, have typically rejected the American approach and found a reasonable expectation of privacy. (65) But in R. v. Tessling, (66) the Supreme Court unanimously held (on the same facts as Kyllo) that warrantless infrared camera searches did not violate [section] 8 of the Charter. "[H]eat distribution," Justice Binnie stated, "offers no insight into [the suspect's] private life, and reveals nothing of his 'biographical core of personal information.'" (67)
The limitations of the intimacy doctrine have also been exposed in a line of cases dealing with searches of third party information databases. In United States v. Miller, the United States Supreme Court held that prosecutors invaded no reasonable expectation of privacy when they subpoenaed a suspect's banking records. (68) The records contained only "information voluntarily conveyed to the banks and exposed to their employees in the ordinary course of business." (69) "The depositor takes the risk, in revealing his affairs to another," the Court reasoned, "that the information will be conveyed by that person to the Government ... even if the information is revealed on the assumption that it will be used only for a limited purpose and the confidence placed in the third party will not be betrayed." (70)
The Supreme Court of Canada has not dealt definitively with banking records, though some of its members have suggested that they do attract a reasonable expectation of privacy. (71) Lower courts have come to varying conclusions. (72) The Supreme Court has decided, however, that no reasonable expectation of privacy was invaded when police obtained a suspect's electrical consumption records from the local utility. (73) "Such records," Justice Sopinka wrote, do not invade that "biographical core of personal information which individuals in a free and democratic society would wish to maintain and control from dissemination to the state." (74) The records, he reasoned, "cannot reasonably be said to reveal intimate details of the appellant's life since electricity consumption reveals very little about the personal lifestyle or private decisions of the occupant of the residence." (75)
III. THE ECONOMIC APPROACH
Can economics point the way to a more determinate and normatively satisfying approach to the reasonable expectation of privacy test? As mentioned, economists typically view privacy as an aspect of rational self-interest. (76) They posit that privacy permits people to conceal (discreditable) personal information that might be used to their disadvantage. (77) It is in people's interest to maximize this ability, selectively disclosing (and thereafter controlling) their personal information to achieve desired ends. (78) This, however, is not always in society's interests. (79) If privacy in a particular realm is used chiefly to conceal socially harmful conduct (such as crime), then legal protection for privacy in that realm should be weak and police should be given broad search powers. If, on the other hand, privacy encourages efficient behaviors, then legal protections should be strong and police powers should be limited. Courts applying the reasonable expectation of privacy test to an investigative technique should thus identify and weigh the costs and benefits of limiting the state's ability to obtain information about criminal suspects.
A. PRIVACY COSTS
The costs of privacy are the easiest to discern. By thwarting the detection and punishment of criminals, legal privacy protections generate two types of social costs. First, most crimes are inefficient, (80) so privacy laws detract from social welfare by diminishing the deterrence of crime. For example, if police cannot use electronic surveillance to acquire evidence that would support an application to obtain a warrant to physically search a suspected drug dealer's home, and there is no other equally effective investigative technique available, fewer physical searches will occur, diminishing the probability of punishment and thus the expected cost of dealing drugs. Drug dealing will thus become a more attractive endeavor. Second, by restricting the use of particular search techniques, privacy laws may force authorities to use more costly substitutes. (81) For example, if police replace electronic surveillance with undercover informants, law enforcement costs may rise, as undercover operations are very likely more expensive and dangerous than electronic surveillance.
B. PRIVACY BENEFITS
Though privacy's social benefits are somewhat more obscure, they are by no means insignificant. While privacy makes it easier for people to engage in antisocial conduct (including crime), it may also provide an incentive for productive activity. (82) Privacy may thus reduce "avoidance costs"; that is, the opportunity cost of forgoing socially beneficial transactions due to the fear of disclosure of information that could be used against those that disclose. There are two types of avoidance costs that privacy laws can mitigate. First, privacy enhances the quantity and quality of interpersonal communications. For example, legal restrictions on eavesdropping (by police or nosy neighbors) free people to communicate more candidly. (83) Privacy diminishes the risk that the information that we rationally disclose to intended recipients will be obtained (and used to our detriment) by unintended recipients. (84) Conversely, widespread eavesdropping causes people to be more formal and guarded in their communications--not only in relation to criminal conversations, but also those revealing discreditable (but non-criminal) information. (85) As Richard Posner states, the "principal effect of allowing eavesdropping would not be to make the rest of society more informed about the individual but to make conversations more cumbersome and less effective." (86) This helps to explain why legal protections against invasions of communicative privacy are so robust. (87)
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