Katz v. United States, 389 U.S. 347 (1967)

The 1967 Supreme Court decision in Katz v. United States revolutionized the interpretation of the Fourth Amendment regarding the extent to which a constitutional right to privacy applies against government interference. The ruling established a new paradigm for evaluating the balance between searches and privacy by establishing that the Constitution protects people, not places. The decision demonstrated the Court’s progress in understanding law and technology, and established a zone of privacy even in accessible areas existing within the public realm.
In Katz, law enforcement agents obtained evidence of an illicit gambling operation by attaching an electronic listening and recording device to the exterior of a public phone booth used by a bookie. Rejecting previous twentieth-century Fourth Amendment jurisprudence geared toward the protection of property and the rule that a trespass to a traditional zone of privacy such as the home or the person was necessary for a violation of the reasonable expectation of privacy, the Court took the revolutionary position that a search may occur even in the absence of a physical penetration of a place. Property rights gave way to the expectation of privacy. The determining question was not whether the telephone booth was a constitutionally protected area, but whether Katz, the bookie, acted in a manner exhibiting the desire to maintain the privacy of his conversation. Thus, although the government’s activities in Katz involved no physical intrusion, they were found to have violated the privacy on which Katz justifiably relied, thereby constituting a search and seizure within the meaning of the Fourth Amendment.
The technologically savvy Court held that the fact that the electronic wiretapping device employed to intercept Katz’s conversation did not penetrate the wall of the phone booth had no constitutional significance. The existence of a recognizable privacy interest turns on whether a person has a subjectively reasonable expectation of privacy in the place or thing searched or seized, and whether society is willing to recognize it as objectively reasonable. The Court articulated that Katz had such a subjectively reasonable expectation of privacy in the content of his conversation within a public yet temporarily enclosed phone booth, and his expectation was one that society was prepared to recognize as reasonable. By entering the phone booth and closing the door, Katz sought to exclude his words (not his physical being) from others. These actions allowed him to reasonably presume that the government’s conduct in recording his conversation violated his justifiable expectation that the content of his conversation would not be broadcast to the world, even absent physical intrusion into the phone booth. This decision extended the scope of the Fourth Amendment beyond the persons, houses, papers, and effects cataloged therein and guaranteed a previously unrecognized privacy right. The right to be let alone by others was officially recognized under the Constitution.
Although the Katz decision was a tremendous victory for privacy advocates, its impact is somewhat limited. A person’s entitlement to protection is not absolute or unrestricted. Protection requires both an actual, subjective expectation of privacy and an objective, reasonable expectation of privacy that society as a whole would be willing to accept.
The Katz holding revolved around the collection of private information without notice through a technological invasion. Thus, its scope is largely limited to content versus non-content material. Non-content materials are not subject to the same extension to the zone of privacy protections. For example, pen register devices, which capture addressing materials rather than content, are outside the scope of the Fourth Amendment (United States v. NY Telephone (1977)). Monitoring or tracking devices that collect location data also may not be included within the zone of privacy protection. Cell-site data fall between content and non-content material. Privacy advocates consider it content material because it is not specifically included in the provisions listing information accessible by subpoena under the Stored Communications Act (SCA). Law enforcement personnel argue that cell-site information provides merely location or tracking material and therefore is clearly non-content information. Their argument is bolstered by the fact that this information is typically collected by the cellular telephone companies for billing and routing purposes. The companies do not collect content information as part of their regular business practice.
Furthermore, the Katz decision did not extend Fourth Amendment protection to the government’s recovery of private information from third parties (Couch v. United States (1973)). The Fourth Amendment has never protected a wrongdoer’s misplaced belief that a person to whom he voluntarily confides his wrongdoing will not reveal it (Hoffa v. United States (1966)). The mandate that the Fourth Amendment protects people and not places did not extend coverage to that level. Account information held by banks (United States v. Miller (1976)), telephone companies (Smith v. Maryland (1979)), and Western Union (In re Grand Jury Proceedings (1987)) has been declared unprotected material because the customer voluntarily conveyed the information to a company and “exposed” the information to its equipment in the ordinary course of business. In so doing, the customer assumed the risk that the company would reveal the information to police or others.
Likewise, the Katz decision has not extended absolute protection to the collection of private information without notice in public areas where privacy is believed to be protected. The government’s intrusion onto an open field (Oliver v. United States (1984)) without a warrant is not proscribed by the Fourth Amendment even if the open field is private property (California v. Ciraolo, 476 U.S. 207 (1986)). Information that is exposed knowingly in an enclosed backyard to the naked eye over great distances by aerial surveillance is not protected (Dow Chemical Co. v. United States (1986)). The rule is that if curtilage (the zone of privacy that one expects to be present around a dwelling or industry site) is open to view, police may observe it from a public area. However, if technology is used that discloses intimate associations, objects, or activities, that conduct may constitute a search implicating Fourth Amendment protection.
The issue concerning the use of enhancement technology has been temporarily resolved by the Supreme Court decision in United States v. Kyllo, 533 U.S. 27 (2001).In Kyllo, the government used a thermal sensor or imaging device on a private residence to detect activity and movement via heat patterns to establish probable cause that the home contained a hydroponic marijuana growing operation. Applying the Katz two-pronged test, the Court concluded that Kyllo did have a subjective expectation of privacy in the heat emissions within his home since the thermal imaging technology had the potential to reveal more than the contraband growing operation. Protected information, such as when the lady of the house was bathing, could also be revealed. Furthermore, the subjective privacy expectation was objectively reasonable and one that society would be willing to recognize. Hence, the interior of house was off limits to any technology, no matter how unobtrusive the technology, provided that the technology was not in general use. This conclusion was reached partly on the basis that the technology of thermal imagers cannot penetrate walls and partly because the devices are not commonly available to the general public. This decision offers minimal and temporary protection to privacy advocates since technology rarely remains static and eventually migrates into the general public domain.
Per the Katz decision and its progeny, the element of property rights is but one factor in determining whether expectations of privacy are legitimate. It is more meaningful and appropriate to examine the actual interests involved, an individual’s liberty balanced against the government’s need for effective law enforcement. The Katz decision is an attempt, in a technologically advanced society, to reaffirm the bedrock constitutional provision that searches conducted outside the judicial process, without prior approval by a judge, are per se unreasonable under the Fourth Amendment—subject only to a few specifically established and well-delineated exceptions.