§ 6.10 Technological Information Gathering
| Jurisdiction | United States |
[A] In General
The Supreme Court shifted away from the trespass doctrine in Katz v. United States in considerable part because, as Justice Harlan put it then, the trespass doctrine constituted "bad physics as well as bad law."136 Technology had reached the point by 1967 that the trespass doctrine no longer seemed to serve as a meaningful limitation on governmental intrusion. By that time, it was possible, and even easy and relatively inexpensive, for the police to intercept conversations without ever trespassing on private property. The technology of 1967, however, pales in comparison to that which has developed in the past few decades, thus placing increasing pressure on Katz's reasonable-expectation-of-privacy doctrine.137 The Supreme Court has focused on two questions in determining whether a new type of surveillance technology constitutes a "Fourth Amendment search."
First, is the device used in the surveillance a technology that is in "general public use"? If so, people's reasonable expectation of privacy will take into account the fact that many members of society use the technology, and therefore the police will have a lot more leeway in using the technology to conduct surveillance. For example, an individual in the early nineteenth century might have had a reasonable expectation of privacy in his activity in a public park in the middle of the night, because he could reasonably assume that nobody could see what he was doing. In modern times, however, the "surveillance technology" of flashlights is commonly used by the public, so a person cannot reasonably expect those actions will be private.
In contrast, a person in a public park does have a reasonable expectation of privacy in the contents of their pockets. If the police developed a new device that allowed them to see through clothing, using that device would be a Fourth Amendment search, because such a device is not in general public use. If in the future these devices became ubiquitous, and everyone commonly used them to look through people's clothing and see inside their pockets, then at that point people would no longer have a reasonable expectation of privacy in the inside of their pockets and the use of these devices by the police would no longer be a Fourth Amendment search.
The second question the Court looks to is the nature of the information that the police obtain when using the surveillance technology. If the device does nothing more than allow the police to gather otherwise public information more easily or efficiently (sometimes referred to as a "sense-enhancing device"), using the device will not usually constitute a Fourth Amendment search. (If the device is gathering massive amounts of public information, which can be processed to reveal private information, using the device could be considered a Fourth Amendment search under the mosaic theory, as described below in Section 6.10[D].) But if the device allows the police to access information that they otherwise could not obtain, then using the device will always constitute a search.
For example, assume the police set up two dozen surveillance cameras in a public park and assign an officer to monitor the video feed from all of the cameras. This surveillance tool will not constitute a search because the police officer is not observing anything that he could not ordinarily observe without the help of the technology — he is merely able to see it more efficiently than before. In contrast, when the police place a wiretap on a telephone, they are conducting a Fourth Amendment search because that surveillance technology reveals information that they could not otherwise have known.
The Supreme Court affirmed these principles in the foundational 2001 case Kyllo v. United States.138 In Kyllo, a federal agent, suspicious that K was using high-intensity lamps in his home to grow marijuana, used a thermal imager to scan the triplex in which K lived. A thermal imager is a device that can "detect infrared radiation, which virtually all objects emit but which is not visible to the naked eye. The imager converts radiation into images based on relative warmth. . . . [I]n that respect, it operates somewhat like a video camera showing heat images." The agent in Kyllo conducted the imaging from his vehicle across the street from K's residence. The scanning showed that the roof of the garage and a side wall of K's home were substantially warmer than the rest of the building. Based on this information and other evidence, the agent obtained a warrant to search the residence. The issue in Kyllo, as Justice Scalia put it for the Court, was "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."
By a vote of 5-4, the Court answered the question in the affirmative and, in the process, announced a new rule to deal with technological advances in existence or in development139 that impinge on the privacy of home dwellers. The majority, quoting language from the pre-Katz era Silverman140 case, stated that:
[w]e 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," . . . , constitutes a search — at least where (as here) the technology in question is not in general public use.
Later, the majority stated the holding of the case this way:
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.141
Although the Kyllo Court did not specifically define what it meant by "general public use," it did provide the following footnote:
The dissent argues that we have injected potential uncertainty into the constitutional analysis by noting that whether or not the technology is in general public use may be a factor. That quarrel, however, is not with us but with this Court's precedent. . . . Given that we can quite confidently say that thermal imaging is not "routine," we decline in this case to reexamine that fact.
Justice Scalia used the Kyllo case again to criticize the Katz test as "circular, and hence subjective and unpredictable," and — presaging his subsequent position in the Jones case — one that may answer the wrong question.142 He stated that it is "difficult" to refine the Katz test in the context of telephone booths, curtilages of homes, and automobiles, but "in the case of the search of the interior of homes . . . there is a ready criterion, with roots deep in the common law." Again quoting pre-Katz Silverman, the majority stated that — "[a]t 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.'"
But what about the fact that thermal imagers only detect relative heat emanations from the home and not intimate details about life inside the dwelling? The Court's answer was: "In the home . . . all details are intimate details, because the entire area is held safe from prying government eyes."143 According to Scalia, "[t]he Fourth Amendment's protection of the home has never been tied to measurement of the quality or quantity of information." A "search" occurs if there is "any physical invasion of the structure of the home, 'by even a fraction of an inch',"144 or if a police officer "barely cracks open the front door and sees nothing but the nonintimate rug on the vestibule floor."
The dissenters would have distinguished between "through-the-wall" surveillance — the type Justice Scalia fears in the future — and "off-the-wall" surveillance. Justice Stevens, author of the dissent, explained:
[T]his case involves nothing more than off-the-wall surveillance . . . to gather information exposed to the general public from the outside of petitioner's home. All that the infrared camera did . . . was passively measure heat emitted from the exterior surfaces of [K's] home. . . . [N]o details regarding the interior of [K's] home were revealed. Unlike an x-ray scan, or other possible "through-the-wall" techniques, the detection of infrared radiation emanating from the home did not accomplish "an unauthorized physical penetration into the premises," nor did it "obtain information that it could not have obtained by observation from outside the curtilage of the house."
Justice Stevens explained that with "ordinary use of the senses" a neighbor could observe the heat emanating from the building, if (as here) it was vented; furthermore, "any member of the public might notice that one part of a house is warmer than another part . . . if, for example, rainwater evaporates or snow melts at different rates across its surfaces."145 Thus, to the dissent, the imager provided information to the police that came "off the wall" and not through it; all the police did is use that information (and tips they had received elsewhere) to infer what was taking place inside.
The Kyllo dissent was correct in one sense: as long as a police officer is present in a lawful vantage point, anything he observes with his naked eye is not a Fourth Amendment search. Thus, a police officer on a public sidewalk who looks through a window into a private home and observes illegal activity has not violated the Fourth Amendment. This is even true if the police officer uses a device to magnify his observations, such as binoculars or a telescope.146 As long as the device is merely "sense-enhancing," use of the device does not constitute a Fourth Amendment search.
A good example of this principle is the pre-Kyllo case Dow Chemical Co. v. United States.147 In Dow Chemical, agents of the Environmental Protection Agency...
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