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Limits On Thermal Imaging Technology
In The War on Drugs


Drug War Uses Thermal Imaging Technology
To Probe Private Homes

A News Analysis  By Terence T. Gorski

Justices Say Warrant Is Required 
in High-Tech Searches of Homes (New York times Article)

Excerpts From Supreme Court Ruling 
on Limits on Surveillance Technology

Terry Gorski and Other Members of the GORSKI-CENAPS Team Are Available To Train & Consult On Areas Related To Drug Law Reform & The War on Drugs
Gorski - CENAPS, 17900 Dixie Hwy, Homewood, IL 60430, 708-799-5000,, 

Drug War Uses Thermal Imaging Technology
To Probe Private Homes

A News Analysis  By Terence T. Gorski
GORSKI-CENAPS Web Publications
Published On: June 12, 2001          Updated On: August 07, 2001
© Terence T. Gorski, 2001

Above is thermal FLIR infrared picture of a building.  The human eye would see nothing but total darkness.  Note the body heat signatures of a row of people on the bottom level in the center of the building.  Devices similar to this have been used to examine private homes without a search warrant.  Supreme Court decision has now stopped that practice.

The drug warriors are continually searching for more intrusive ways to stamp out the use of illegal drugs in this country.  One of the potentially most intrusive is the use of thermal imaging technology that is capable of detecting patterns of heat coming from private homes.  Recently various generations of this technology have been deployed by police to search for in home marijuana cultivation by detecting the heat emitted from growing lamps.  The most widely used technologies detect patterns of heat escaping from the surfaces of homes and cannot detect details of occupants movements.  The more sophisticated technology is capable imaging the bodies in the house and tracking their movements by detecting their heat signatures.  Thermal imaging technology has been deployed from ground vehicles and from low flying helicopters. 

On June 11,  2001 the Supreme Court validated the constitutionally guaranteed right to privacy by ruling that the use of thermal imaging technology and any similar future surveillance technologies requires a search warrant.  Read about the details in the article below.

Justices Say Warrant Is Required in High-Tech Searches of Homes


WASHINGTON, June 11 — In an important declaration of the constitutional limits on new privacy- threatening technology, the Supreme Court ruled today that the use by the police of a thermal imaging device to detect patterns of heat coming from a private home is a search that requires a warrant.

The court said further that the warrant requirement would apply not only to the relatively crude device at issue but also to any "more sophisticated systems" in use or in development that let the police gain knowledge that in the past would have been impossible without a physical entry into the home.

"We must take the long view, from the original meaning of the Fourth Amendment forward," Justice Antonin Scalia wrote for a 5-to-4 majority that cut across the court's usual ideological division. [Excerpts, Page A29.]

Justice Scalia said that to take any other approach "would leave the homeowner at the mercy of advancing technology — including imaging technology that could discern all human activity in the home."

The decision overturned a ruling by the United States Court of Appeals for the Ninth Circuit in San Francisco — often regarded as the most liberal of the federal appeals courts — which held in 1999 that the warrantless use of a device that revealed patterns of heat suggestive of an indoor marijuana-growing operation did not violate the Fourth Amendment's prohibition of unreasonable searches.

In a dissenting opinion today, Justice John Paul Stevens — who in turn is usually described as the court's most liberal justice — said the Ninth Circuit was correct and that the police activity in the case "did not invade any constitutionally protected interest in privacy." He said that for the court today to make a constitutional rule about future technology was "unnecessary, unwise and inconsistent with the Fourth Amendment."

Those who joined Justice Scalia in the majority were Justices David H. Souter, Clarence Thomas, Ruth Bader Ginsburg and Stephen G. Breyer. Chief Justice William H. Rehnquist joined the dissent, as did Justices Sandra Day O'Connor and Anthony M. Kennedy.

The case, Kyllo v. United States, No. 99-8508, was a federal drug prosecution that began in 1992, when two federal agents trained a device called Agema Thermovision 210 on a home in Florence, Ore., where, on the basis of tips and utility bills, they believed marijuana was being grown under high-intensity lamps. While the imager cannot see through walls, it can detect hot spots, and in this case disclosed that part of the roof and a side wall were warmer than the rest of the building and the neighboring houses.

The agents used that information to get a warrant to enter and search the home, where they found more than 100 marijuana plants growing under halide lights. The resident, Danny Kyllo, entered a conditional guilty plea while continuing to contest the validity of the search. He served one month in jail.

When Mr. Kyllo's Supreme Court appeal was argued in February, the government strongly defended use of thermal imagers on the ground that in detecting heat loss, the devices neither reveal private information nor violate the "reasonable expectation of privacy" that is the Supreme Court's test under the Fourth Amendment.

But in the home, Justice Scalia said today "all details are intimate details, because the entire area is held safe from prying government eyes." Noting that the court's precedents draw "a firm line at the entrance to the house," he added, "That line, we think, must be not only firm but also bright."

Despite its forceful language, the decision was undoubtedly not the court's final word on the subject of privacy and technology. Justice Scalia's emphasis on the home raised the prospect that warrantless imaging of other locations might be upheld. And it is far from clear under the court's precedents that a person in a home that belonged to someone else would have standing to challenge the use of an imager.

Further, the majority limited its holding to devices that are "not in general public use," without explaining that limitation. In his dissenting opinion, Justice Stevens said this limitation was "somewhat perverse because it seems likely that the threat to privacy will grow, rather than recede, as the use of intrusive equipment becomes more readily available."

Nonetheless, the decision was important and "surprisingly broad," said James J. Tomkovicz, a law professor at the University of Iowa who filed a brief for the National Association of Criminal Defense Lawyers and the American Civil Liberties Union.

"It was important for the court to say that there are general limits on the ability of technological developments to erode Fourth Amendment privacy," he said in an interview.

The vote today underscored the unpredictable, if not incoherent, nature of the court's rulings on the Fourth Amendment, currently an extremely active area of the court's jurisdiction. Last year, for example, the court ruled that police officers had conducted an unconstitutional search when they walked down the aisle of a long-distance bus and squeezed passengers' overhead luggage to look for contraband. Chief Justice Rehnquist wrote the 7-to-2 opinion in that case, Bond v. United States, while Justices Scalia and Breyer dissented.

On display today was Justice Scalia's insistence that the Fourth Amendment be interpreted according to the understanding of its framers.

Requiring a warrant to use technology that displaces an old-fashioned search "assures preservation of that degree of privacy against government that existed when the Fourth Amendment was adopted," Justice Scalia said.

For Justice Stevens, on the other hand, the problem with the majority opinion appeared to be its sweeping nature.

In crafting "an all-encompassing rule for the future," Justice Stevens said, the court "has unfortunately failed to heed the tried and true counsel of judicial restraint." He added, "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."

Excerpts From Supreme Court Ruling on Limits on Surveillance Technology


WASHINGTON, June 11 — Following are excerpts from the Supreme Court's decision today that the police must obtain a warrant before using a heat-sensing device to search for illegal activity in a home. The vote in Kyllo v. United States was 5 to 4. Justice Antonin Scalia wrote the majority opinion, and Justice John Paul Stevens wrote the dissent.


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 "the 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." With few exceptions, the question whether a warrantless search of a home is reasonable and hence constitutional must be answered no.

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." 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), "the 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, 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.

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. For example, as the cases discussed above make clear, the technology enabling human flight has exposed to public view (and hence, we have said, to official observation) uncovered portions of the house and its curtilage that once were private. The question we confront today is what limits there are upon this power of technology to shrink the realm of guaranteed privacy.

The Katz [v. United States] 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 that exists, 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" 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.

Terry Gorski and Other Members of the GORSKI-CENAPS Team Are Available To Train & Consult On Areas Related To Addiction & Mental Health
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