Kyllo v. United States

533 U.S. 27

Case Year: 2001

Case Ruling: 5-4, Reversed and Remanded

Opinion Justice: Scalia

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Concurring Opinions

Dissenting Opinions

Court Opinion Joiner(s):

Breyer, Ginsburg, Souter, Thomas


1st Concurring Opinion



1st Dissenting Opinion

Author: Stevens

Joiner(s): Kennedy, O'Connor, Rehnquist

2nd Concurring Opinion



2nd Dissenting Opinion



3rd Concurring Opinion



3rd Dissenting Opinion



Other Concurring Opinions:


In 1991, Agent William Elliott of the U.S. Interior Department suspected that Danny Kyllo was growing marijuana in his home. Kyllo lived in one part of a triplex on Rhododendron Drive in Florence, Oregon. To confirm his suspicions, Elliott used a thermal imaging device to measure the amount of heat loss occurring in the triplex. Given the number of grow lamps needed to cultivate marijuana indoors, an area of a home showing high levels of heat would be consistent with growing a large number of plants inside. The procedure took place at 3:20 a.m. on January 16, 1992. To conduct the scan, Elliott did not have to set foot on Kyllo's property. The scan was carried out from Elliott's car parked on the street adjacent to the triplex. The results were as Elliott expected. The imaging device showed an excessive amount of heat over the garage area and coming from a side wall of Kyllo's unit. Heat loss from this area was much greater than from any other point on the triplex. Elliott also checked utility bills in the immediate area and found that Kyllo's power consumption was significantly higher than that of his neighbors. Based on the power bills, scan results, and informants' tips, a judge issued a warrant to search Kyllo's home. The subsequent search yielded over one hundred marijuana plants.

Kyllo was charged with illegally growing marijuana. The district court rejected his attempt to get the thermal imaging evidence excluded from the trial. A court of appeals affirmed this decision. Although the thermal imaging device was used without warrant, the lower courts concluded that the apparatus could only provide crude measurements of heat loss. It was unable to reveal any information about specific activities or conversations that occurred within the home. Thus, there were no violations of Kyllo's privacy or of his Fourth Amendment rights.



This case presents the question whether the use of a thermal-imaging device aimed at a private home from a public street to detect relative amounts of heat within the home constitutes a "search" within the meaning of the Fourth Amendment....

The Fourth Amendment provides that "[t]he right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated." "At the very core" of the Fourth Amendment "stands the right of a man to retreat into his own home and there be free from unreasonable governmental intrusion." Silverman v. United States (1961). With few exceptions, the question whether a warrantless search of a home is reasonable and hence constitutional must be answered no. See Illinois v. Rodriguez (1990); Payton v. New York (1980).

On the other hand, the antecedent question of whether or not a Fourth Amendment "search" has occurred is not so simple under our precedent. The permissibility of ordinary visual surveillance of a home used to be clear because, well into the 20th century, our Fourth Amendment jurisprudence was tied to common-law trespass.... Visual surveillance was unquestionably lawful because "'the eye cannot by the laws of England be guilty of a trespass.'" Boyd v. United States (1886). We have since decoupled violation of a person's Fourth Amendment rights from trespassory violation of his property, ... but the lawfulness of warrantless visual surveillance of a home has still been preserved. As we observed in California v. Ciraolo(1986), "[t]he Fourth Amendment protection of the home has never been extended to require law enforcement officers to shield their eyes when passing by a home on public thoroughfares."

One might think that the new validating rationale would be that examining the portion of a house that is in plain public view, while it is a "search" despite the absence of trespass, is not an "unreasonable" one under the Fourth Amendment.... But in fact we have held that visual observation is no "search" at all--perhaps in order to preserve somewhat more intact our doctrine that warrantless searches are presumptively unconstitutional.... In assessing when a search is not a search, we have applied somewhat in reverse the principle first enunciated in Katz v. United States (1967). Katz involved eavesdropping by means of an electronic listening device placed on the outside of a telephone booth--a location not within the catalog ("persons, houses, papers, and effects") that the Fourth Amendment protects against unreasonable searches. We held that the Fourth Amendment nonetheless protected Katz from the warrantless eavesdropping because he "justifiably relied" upon the privacy of the telephone booth.... As Justice Harlan's oft-quoted concurrence described it, a Fourth Amendment search occurs when the government violates a subjective expectation of privacy that society recognizes as reasonable.... We have subsequently applied this principle to hold that a Fourth Amendment search does not occur--even when the explicitly protected location of a house is concerned--unless "the individual manifested a subjective expectation of privacy in the object of the challenged search," and "society [is] willing to recognize that expectation as reasonable."... We have applied this test in holding that it is not a search for the police to use a pen register at the phone company to determine what numbers were dialed in a private home, Smith v. Maryland (1979), and we have applied the test on two different occasions in holding that aerial surveillance of private homes and surrounding areas does not constitute a search,Florida v. Riley (1989).

The present case involves officers on a public street engaged in more than naked-eye surveillance of a home. We have previously reserved judgment as to how much technological enhancement of ordinary perception from such a vantage point, if any, is too much. While we upheld enhanced aerial photography of an industrial complex in Dow Chemical, we noted that we found "it important that this is not an area immediately adjacent to a private home, where privacy expectations are most heightened."

It would be foolish to contend that the degree of privacy secured to citizens by the Fourth Amendment has been entirely unaffected by the advance of technology....... The question we confront today is what limits there are upon this power of technology to shrink the realm of guaranteed privacy.

The Katz test--whether the individual has an expectation of privacy that society is prepared to recognize as reasonable--has often been criticized as circular, and hence subjective and unpredictable.... While it may be difficult to refine Katz when the search of areas such as telephone booths, automobiles, or even the curtilage and uncovered portions of residences are at issue, in the case of the search of the interior of homes--the prototypical and hence most commonly litigated area of protected privacy--there is a ready criterion, with roots deep in the common law, of the minimal expectation of privacy thatexists, and that is acknowledged to be reasonable. To withdraw protection of this minimum expectation would be to permit police technology to erode the privacy guaranteed by the Fourth Amendment. We think that obtaining 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," Silverman constitutes a search--at least where (as here) the technology in question is not in general public use. This assures preservation of that degree of privacy against government that existed when the Fourth Amendment was adopted. On the basis of this criterion, the information obtained by the thermal imager in this case was the product of a search.

The Government maintains, however, that the thermal imaging must be upheld because it detected "only heat radiating from the external surface of the house."... The dissent makes this its leading point, ... contending that there is a fundamental difference between what it calls "off-the-wall" observations and "through-the-wall surveillance." But just as a thermal imager captures only heat emanating from a house, so also a powerful directional microphone picks up only sound emanating from a house--and a satellite capable of scanning from many miles away would pick up only visible light emanating from a house. We rejected such a mechanical interpretation of the Fourth Amendment in Katz, where the eavesdropping device picked up only sound waves that reached the exterior of the phone booth. Reversing that approach would leave the homeowner at the mercy of advancing technology--including imaging technology that could discern all human activity in the home. While the technology used in the present case was relatively crude, the rule we adopt must take account of more sophisticated systems that are already in use or in development. The dissent's reliance on the distinction between "off-the-wall" and "through-the-wall" observation is entirely incompatible with the dissent's belief, which we discuss below, that thermal-imaging observations of the intimate details of a home are impermissible. The most sophisticated thermal imaging devices continue to measure heat "off-the-wall" rather than "through-the-wall"; the dissent's disapproval of those more sophisticated thermal-imaging devices is an acknowledgement that there is no substance to this distinction. As for the dissent's extraordinary assertion that anything learned through "an inference" cannot be a search ... that would validate even the "through-the-wall" technologies that the dissent purports to disapprove. Surely the dissent does not believe that the through-the-wall radar or ultrasound technology produces an 8-by-10 Kodak glossy that needs no analysis ( i.e., the making of inferences). And, of course, the novel proposition that inference insulates a search is blatantly contrary to United States v. Karo (1984), where the police "inferred" from the activation of a beeper that a certain can of ether was in the home. The police activity was held to be a search, and the search was held unlawful.

The Government also contends that the thermal imaging was constitutional because it did not "detect private activities occurring in private areas."... It points out that in Dow Chemical we observed that the enhanced aerial photography did not reveal any "intimate details." Dow Chemical, however, involved enhanced aerial photography of an industrial complex, which does not share the Fourth Amendment sanctity of the home. The Fourth Amendment's protection of the home has never been tied to measurement of the quality or quantity of information obtained. In Silverman, for example, we made clear that any physical invasion of the structure of the home, "by even a fraction of an inch," was too much, and there is certainly no exception to the warrant requirement for the officer who barely cracks open the front door and sees nothing but the nonintimate rug on the vestibule floor. In the home, our cases show, all details are intimate details, because the entire area is held safe from prying government eyes. Thus, in Karo the only thing detected was a can of ether in the home; and in Arizona v. Hicks (1987), the only thing detected by a physical search that went beyond what officers lawfully present could observe in "plain view" was the registration number of a phonograph turntable. These were intimate details because they were details of the home, just as was the detail of how warm--or even how relatively warm--Kyllo was heating his residence....

We have said that the Fourth Amendment draws "a firm line at the entrance to the house," Payton. That line, we think, must be not only firm but also bright--which requires clear specification of those methods of surveillance that require a warrant. While it is certainly possible to conclude from the videotape of the thermal imaging that occurred in this case that no "significant" compromise of the homeowner's privacy has occurred, we must take the long view, from the original meaning of the Fourth Amendment forward....

Where, as here, the Government uses a device that is not in general public use, to explore details of the home that would previously have been unknowable without physical intrusion, the surveillance is a "search" and is presumptively unreasonable without a warrant....

The judgment of the Court of Appeals is reversed; the case is remanded for further proceedings consistent with this opinion.

It is so ordered.


There is, in my judgment, a distinction of constitutional magnitude between "through-the-wall surveillance" that gives the observer or listener direct access to information in a private area, on the one hand, and the thought processes used to draw inferences from information in the public domain, on the other hand. The Court has crafted a rule that purports to deal with direct observations of the inside of the home, but the case before us merely involves indirect deductions from "off-the-wall" surveillance, that is, observations of the exterior of the home. Those observations were made with a fairly primitive thermal imager that gathered data exposed on the outside of petitioner's home but did not invade any constitutionally protected interest in privacy. Moreover, I believe that the supposedly "bright-line" rule the Court has created in response to its concerns about future technological developments is unnecessary, unwise, and inconsistent with the Fourth Amendment.

There is no need for the Court to craft a new rule to decide this case, as it is controlled by established principles from our Fourth Amendment jurisprudence. One of those core principles, of course, is that "searches and seizures inside a homewithout a warrant are presumptively unreasonable." Payton v. New York (1980) (emphasis added). But it is equally well settled that searches and seizures of property in plain view are presumptively reasonable. Whether that property is residential or commercial, the basic principle is the same: "'What a person knowingly exposes to the public, even in his own home or office, is not a subject of Fourth Amendment protection.'" California v. Ciraolo, (1986) (quoting Katz v. United States (1967)).... That is the principle implicated here....

To be sure, the homeowner has a reasonable expectation of privacy concerning what takes place within the home, and the Fourth Amendment's protection against physical invasions of the home should apply to their functional equivalent. But the equipment in this case did not penetrate the walls of petitioner's home, and while it did pick up "details of the home" that were exposed to the public, ... it did not obtain "any information regarding the interior of the home." In the Court's own words, based on what the thermal imager "showed" regarding the outside of petitioner's home, the officers "concluded" that petitioner was engaging in illegal activity inside the home. It would be quite absurd to characterize their thought processes as "searches," regardless of whether they inferred (rightly) that petitioner was growing marijuana in his house, or (wrongly) that "the lady of the house [was taking] her daily sauna and bath." In either case, the only conclusions the officers reached concerning the interior of the home were at least as indirect as those that might have been inferred from the contents of discarded garbage, see California v. Greenwood (1988), or pen register data, see Smith v. Maryland (1979), or, as in this case, subpoenaed utility records. For the first time in its history, the Court assumes that an inference can amount to a Fourth Amendment violation....

Since what was involved in this case was nothing more than drawing inferences from off-the-wall surveillance, rather than any "through-the-wall" surveillance, the officers' conduct did not amount to a search and was perfectly reasonable....

Although the Court is properly and commendably concerned about the threats to privacy that may flow from advances in the technology available to the law enforcement profession, it has unfortunately failed to heed the tried and true counsel of judicial restraint. Instead of concentrating on the rather mundane issue that is actually presented by the case before it, the Court has endeavored to craft an all-encompassing rule for the future. It would be far wiser to give legislators an unimpeded opportunity to grapple with these emerging issues rather than to shackle them with prematurely devised constitutional constraints.

I respectfully dissent.