Law is the formal embodiment of rules that legislators, regulators, and judges etch into statute books, administrative manuals, and judicial decisions. It is unavoidable and desirable to see the law change as technology becomes increasingly sophisticated.

Before there were automobiles and aircraft, there was no need for a law prohibiting their theft.[1] Similarly, before there were telecommunications systems, there was no need for a law to protect the integrity of the conversations of subscribers.[2] And before there were electronic devices such as satellites, digital cameras, and Cray computers, there was no reason to be concerned with the government’s use of those tools to find, identify, acquire, analyze, and store significant amounts of information about Americans.

Today, however, these new technologies are a reality and society must decide how to regulate their use—particularly with regard to government surveillance. The use of those devices for law enforcement offers potential benefits and costs, and society ought to debate the pros and cons of the trade-off between efficiency and efficacy of law enforcement techniques and the privacy rights of citizens the government may wish to monitor.

The opportunity for such a debate arises because of the public nature of criminal trials and the constitutional evidentiary rules governing the government’s use of evidence acquired by modern surveillance technology. If the government seeks to prove a defendant’s guilt by using evidence derived from its reliance on advanced technologies, defendants can demand that the courts review the legality of the government’s conduct, and judges will be forced to bless or condemn the use of whatever evidence the government seeks to introduce. Those decisions then define what the Fourth Amendment means.

The Relationship Between the Fourth Amendment and Technology

The Fourth Amendment provides as follows:

The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.

The amendment prohibits the government from conducting unreasonable “searches” and “seizures.” The exclusionary rule enforces the amendment by prohibiting federal, state, or local judges from admitting in the government’s case-in-chief evidence obtained in violation of the Fourth Amendment.[3] Parties injured by an unlawful search or seizure can also bring a damages action against the officers involved, but the exclusionary rule has made criminal trials the most likely forum for a public airing of competing versions of what the Fourth Amendment should protect.

Yet, even though the Fourth Amendment has been a fundamental part of American jurisprudence for nearly 225 years—and the exclusionary rule a constitutionally required remedy for nearly a century[4]—the question of whether reliance on sensory-enhancing technology can render a search or seizure unreasonable is a relatively new one. No one seems to have challenged a sheriff’s use of spectacles or torches to improve his day or night vision,[5] although it is certain that one or more constables or local residents called out as part of a “hue and cry” or Old West posse must have used them. Perhaps, glasses and torches were so widely used and seemed so reasonable that no one thought to question them, or perhaps they were used, not to acquire proof of a suspect’s guilt, but just to find him. Whatever the reason, it seems that it was not until society harnessed electricity and invented telephones that anyone thought to challenge law enforcement’s use of sensory-enhancement technology.

The Supreme Court first addressed the issue in 1927. Specifically, in United States v. Lee,[6] the Court held that shining a deck-mounted spotlight onto the open deck of a vessel used for rum running did not constitute a “search” for purposes of the Fourth Amendment.[7] Rather than treat the defendant’s claim as raising a novel Fourth Amendment issue, the Court gave it the back of the hand.[8]

The following year, the Court held in Olmstead v. United States[9] that the interception of telephone communications not requiring a physical trespass onto a person’s property—colloquially known as “bugging”—also did not constitute a search or seizure. The officers listened in on Olmstead’s phone conversation, not by entering his home, but by attaching intercept equipment to phone lines found elsewhere. Because that form of eavesdropping did not involve a trespass, the Court ruled that a search had not occurred.

That is where the law stood for the next four decades,[10] until 1967, when the Supreme Court decided Katz v. United States.[11]

The issues raised in Katz stem from the following fact pattern: Charles Katz was using a public outdoor telephone booth to engage in an activity familiar to all March Madness fans: gambling on sporting events. Unbeknownst to Katz, the FBI had attached an electronic listening and recording device to the outside of the phone booth, and the government used the content of his recorded communications against Katz at a trial for violating the federal gambling laws. Breaking new ground, the Supreme Court reversed, ruling that the government had unlawfully violated Katz’s privacy interest in the content of his conversations.

The Court started by noting that “the correct solution of Fourth Amendment problems is not necessarily promoted by incantation of the phrase ‘constitutionally protected area’” and that “the Fourth Amendment cannot be translated into a general constitutional ‘right to privacy.’”[12] As the Court reasoned, the Fourth Amendment “protects individual privacy against certain kinds of governmental intrusion, but its protections go further, and often have nothing to do with privacy at all.”[13]

Eschewing its prior use of the term “constitutionally protected area” to define the scope of the Fourth Amendment,[14] the Court wrote that asking whether an outdoor public phone booth was “a constitutionally protected area” was a mistake,[15] because “the Fourth Amendment protects people, not places.”[16] On the one hand, the Court reasoned, “[w]hat a person knowingly exposes to the public, even in his own home or office, is not a subject of Fourth Amendment protection,” while, on the other hand, “what he seeks to preserve as private, even in an area accessible to the public, may be constitutionally protected.”[17]

The fact that Katz was visible when he used the telephone was irrelevant, the Court noted, because what Katz could justifiably seek protection from was not “the intruding eye,” but “the uninvited ear.”[18] Concluding that “searches conducted outside the judicial process, without prior approval by judge or magistrate, are per se unreasonable under the Fourth Amendment subject only to a few specifically established and well-delineated exceptions,”[19] none of which was applicable there, the Court ruled that the government’s conduct violated the Fourth Amendment.

Katz seemed to be a watershed decision in Fourth Amendment law. The Court rejected the proposition that common law trespass law defined the scope of the Fourth Amendment[20] and appeared to endorse the two-pronged test, articulated by Justice Harlan in his concurring opinion: the Fourth Amendment safeguards privacy interests that an individual and society deem reasonable.[21] Katz signaled that the Supreme Court might rethink its entire approach to Fourth Amendment coverage by using privacy rather than property concepts. Some applauded that prospect; others feared it. As it turned out, however, the Court did not go very far down the road that supporters and critics anticipated.

Post-Katz Case Law

The Court often has reiterated the two-pronged inquiry that Justice Harlan articulated in Katz as a means of defining a “search.”[22] At the same time, however, the Court has not eschewed reliance on property rules to define the contours of searches and seizures, and, on occasion, has specifically relied on such rules in determining whether a search or seizure has occurred. For example, the Court in Katz ruled that a person who enters a phone booth does not assume the risk of being overheard. By contrast, in United States v. White,[23] the Court held that a person who invites someone into his or her home assumes the risk, not only of being betrayed, but also of being recorded. Katz rejected reliance on arcane rules of property law to define the scope of the Fourth Amendment. By contrast, Oliver v. United States[24] reaffirmed the proposition that the Fourth Amendment does not apply to the “open fields” because the crown could enter upon them at common law.[25] The Court in Katz endorsed a privacy-based approach to the Fourth Amendment. By contrast, the Court in United States v. Miller[26] and Smith v. Maryland[27] concluded that once a person allows someone else access to personal information, any privacy interest in that information is gone forever.[28] And recently in United States v. Jones,[29] the Court held that the physical placement of a GPS tracking device on a person’s vehicle and subsequent monitoring of its movements constituted a search for Fourth Amendment purposes, because the placement constituted a trespass under the common law.

As a result of these decisions, parties who had hoped for a revolution in Fourth Amendment law have been disappointed—not only by the results of the Supreme Court’s post-Katz case law, but also by what they see as the Court’s abandonment of its promised concern for individual privacy. As Professor Anthony Amsterdam once wrote: “I can conceive of no rational system of concerns and values that restricts the government’s power to rifle my drawers or tap my telephone but not its power to infiltrate my home or my life with a legion of spies.”[30]

For privacy advocates, however, all is not lost. In recent Supreme Court case law there have been stirrings of a renewed interest in a privacy-based analysis of the Fourth Amendment. A few decisions have given privacy advocates hope that perhaps the Court is concerned after all about the use of new technologies to intrude on Americans’ “persons, houses, places, and effects.” For example, in Kyllo v. United States,[31] the Court held that use of thermal-imaging technology—a device that measures heat emissions from within a structure—to learn what is transpiring within a home did, in fact, constitute a search. Similarly, in Florida v. Jardines,[32] the Court found that a new use for an old technology—i.e., a dog’s exceptional ability to sniff out items such as drugs—can amount to an invasion of privacy if the dog is in a place that man’s best friend is not entitled to be.[33] And, in Maryland v. King,[34] a closely divided Court upheld the use of suspicionless buccal swabbing (a relatively non-invasive way of collecting cells from the inside of one’s cheek) for the purpose of performing a DNA analysis of an arrestee only in limited circumstances (i.e., the arrest was for a serious crime, and the DNA analysis did not disclose genetic or medical information) and so long as the information gleaned was not recorded in a database compiling genetic or medical information.[35] Indeed, privacy advocates are particularly encouraged by the fact that the Court’s newfound interest in privacy protection seems to extend across the conservative-liberal divide.[36]

How Will the Supreme Court Apply the Fourth Amendment to New Technologies?

The Kyllo, Jones, and King cases offer excellent examples of technologies that did not exist when the Supreme Court decided Katz. And there are a host of other information gathering, analyzing, and recording devices that raise the same types of concerns that motivated the Court in Katz to focus on a person’s privacy—rather than property rights—as the locus of Fourth Amendment concern.

Consider the Global Positioning Satellite (GPS) system.[37] The GPS system identifies a specific person’s cell phone location within meters.[38] Cell phone manufacturers and telecommunications companies installed GPS software in cell phones in order to make it easier for law enforcement and emergency medical services teams to respond to 911 calls.[39] Now, however, the same tool allows law enforcement to track a person’s movements as long as he or she is carrying an operational cell phone.[40] There will be considerable litigation over the circumstances in which law enforcement can obtain GPS tracking information.[41]

Predicting where the Supreme Court will take Fourth Amendment law in connection with new technologies based on the few and vague suggestions set forth in the majority, concurring, and dissenting opinions in cases such as Kyllo, Jones, Jardines, and King is a more hazardous undertaking than Joseph’s analysis of the Pharaoh’s dreams.[42] Nonetheless, there are a few predictions that can be made with a tolerable degree of certainty.

First, like a military Explosives Ordinance Disposal technician attempting to clear a minefield, the Court is likely to address new technologies deliberately, and incrementally, using the old-fashioned common law, case-by-case approach to decision making—rather than attempt to devise broad rules that would decide a large category of cases not presently before the Court.[43] Indeed, the Court has expressed a reluctance to decide more than what is necessary to resolve the particular case before it, partially because judges are not in a position to fully understand contemporary technology (let alone to anticipate future developments) or society’s likely reaction to them.[44]

In that process the Court might be willing to reconsider old doctrines. Some parties have urged the Court to reconsider its precedents in light of new technologies and changed attitudes.[45] Justice Sotomayor, for one, has signaled her willingness to reconsider the so-called third-party doctrine under which a person has no reasonable expectation of privacy in information voluntarily disclosed to a third party.[46] On the other hand, Justice Alito, joined by Justices Ginsburg, Breyer, and Kagan, has indicated an unwillingness to abandon the “reasonable expectation of privacy” test adopted in Katz and to return Fourth Amendment law to a property rights–based approach.[47] Whether the Court goes forward, backward, or nowhere remains to be seen.

Second, the Court, in construing the Constitution, may recognize that a haunting presence—9/11—compels the Congress and the President to obtain information necessary for the defense of the nation against the type of assaults suffered on that day. The Court may come to see that the need to prevent certain potential catastrophic terrorist actions (e.g., detonation of a “dirty” bomb in a major metropolitan area) is far weightier than the need to solve a common law crime (e.g., burglary) and tips the balance in the government’s favor.

The idea that the government’s need for information ranges from the essential to the trivial is not a new one. Justice Robert Jackson once suggested that the Court should interpret the Fourth Amendment differently in cases involving child kidnapping and bootlegging.[48] For the most part, the Court has not accepted his suggestion,[49] and the Court has not calibrated Fourth Amendment protections according to the seriousness of the offense being investigated. The best example of that approach is the Court’s 2001 decision in City of Lago Vista, which rejected the argument that the Fourth Amendment prohibited a warrantless custodial arrest for misdemeanors not amounting to a “breach of the peace,” such as not wearing a seatbelt.[50] Perhaps the Court has been unwilling to distinguish between misdemeanors and felonies, and even among the various types of crimes denominated felonies, for Fourth Amendment purposes because the Court sees that function as a legislative one. Whatever the reason, the Court has accepted an “in for a dollar, in for a dime” approach to Fourth Amendment decision making. That may change. The Supreme Court may determine that it needs to give more weight to the government’s need for intelligence information in order to protect the nation against a repeat of 9/11.

And in cases involving foreign threats to national security,[51] the Court has left itself room to do just that. For example, the Court has approved certain types of warrantless and suspicionless searches that are performed not to obtain evidence for use in a criminal prosecution, but to secure information for use in other, very different contexts.[52] Recently, the Court went out of its way to limit its approval of certain government practices—DNA testing of arrestees—to parties taken into custody for “serious” offenses.[53] In coming years, the Court may find itself confronting cases involving presidential power to collect foreign intelligence.

Third, if the Court grants the federal government such unrestricted authority to obtain private information for counterterrorism uses, the Court may also decide that it needs to modify the exclusionary rule in order to limit the government’s use of that evidence for only intelligence or antiterrorism purposes. That is, the Court could decide that the government may use sophisticated electronic information acquisition and analysis technology in order to protect the nation against terrorist threats, but may not use that information in an ordinary criminal prosecution unrelated to the need that justified the original search or seizure. The Court will have to sort out competing constitutional values involving both law enforcement, military, and foreign intelligence needs and the privacy of Americans.

Fourth, the Court may postpone addressing many aspects of the relationship between the Fourth Amendment and new technologies in order to see if Congress will tackle the problem by adopting a new regulatory scheme balancing information gathering needs and privacy considerations. Four justices already have made that point.[54]

On the other hand, reluctant to anger any sizeable portion of the electorate, especially one that tends to make its opinions known in the print or electronic media, Members of Congress may decide to let the federal courts make the trade-off, at least in the first instance, in order to gauge the public’s response before taking a position of their own. Congress therefore might try to wait until the Supreme Court decides the Fourth Amendment issues before swooping in to shoot the survivors.

Conclusion

The Fourth Amendment was not designed to serve as a static protection against government abuse. No provision of the Bill of Rights—particularly one outlawing “unreasonable” searches and seizures—could or should be cabined to the specific historical incidents that gave it birth. That construction would render the amendment a safeguard for the peculiar historical incidents that troubled late eighteenth century Americans rather than a guarantee that law enforcement officers act reasonably today and tomorrow.

At the same time, the Framers knew that foreign nations like England possessed superior military strength and could inflict considerable damage on the new nation on land or at sea. They likely would not have found unimaginable the need to make a trade-off between liberty and security, or to reassess that trade-off as times change. Today, hostile private organizations such as al-Qaeda possess the organizational infrastructure, financial strength, and communications abilities that nations could not have imagined in the eighteenth century, and weapons of mass destruction offer terrorist cells the ability to inflict far greater damage on this country than England’s Royal Army and Navy could have inflicted on us two centuries ago. Such risks should count for something when the issue is whether the government has acted “reasonably.”

How will the Supreme Court make that trade-off with regard to technologies unheard of two decades ago, to say nothing of two centuries ago? Nothing is certain. We will learn the answer only as specific cases push the Court to balance the still critical needs for security and liberty.