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Kyllo v. United States

Kyllo v. United States
Argued February 20, 2001
Decided June 11, 2001
Full case name Danny Lee Kyllo v. United States
Citations 533 U.S. 27 (more)
121 S. Ct. 2038; 150 L. Ed. 2d 94; 69 U.S.L.W. 4431; 2001 U.S. LEXIS 4487; 2001 Cal. Daily Op. Service 4749; 2001 Daily Journal DAR 5879; 2001 Colo. J. C.A.R. 2926; 14 Fla. L. Weekly Fed. S 329
Prior history On writ of certiorari to the United States Court of Appeals for the Ninth Circuit
Thermal imaging of a home constitutes a Fourth Amendment "search" and may be done only with a warrant.
Court membership
Case opinions
Majority Scalia, joined by Souter, Thomas, Ginsburg, Breyer
Dissent Stevens, joined by Rehnquist, O'Connor, Kennedy
Laws applied
U.S. Const. amend. IV

Kyllo v. United States, 533 U.S. 27 (2001), held that the use of a thermal imaging, or FLIR, device from a public vantage point to monitor the radiation of heat from a person's home was a "search" within the meaning of the Fourth Amendment, and thus required a warrant.


  • Facts 1
  • Opinion of the Supreme Court 2
  • See also 3
  • References 4
  • External links 5


Department of the Interior used a thermal imaging device outside of Danny Lee Kyllo's home in Florence, Oregon. According to the District Court that presided over Kyllo's evidentiary hearing, the device could not "penetrate walls or windows to reveal conversations or human activities. The device recorded only heat being emitted from the home." The device showed that there was an unusual amount of heat radiating from the roof and side walls of the garage compared with the rest of his house. (The assumption is that to grow marijuana indoors, one needs to provide a large amount of light in order for the plants to photosynthesize.) This information was subsequently used to obtain a search warrant, where federal agents discovered over 100 marijuana plants growing in Kyllo's home. Kyllo was charged with growing marijuana in his Oregon home. Kyllo first tried to suppress the evidence obtained from the thermal imaging search, but then he pled a conditional guilty. Kyllo appealed to the Ninth Circuit Court on the grounds that observations with a thermal-imaging device constituted a search under the Fourth Amendment. At the Court of Appeals, the conviction was upheld. Kyllo petitioned a writ of certiorari to the Supreme Court.

Opinion of the Supreme Court

The Supreme Court ruled 5-4 that the thermal imaging of Kyllo's home constituted a search. Since the police did not have a warrant when they used the device, which was not commonly available to the public, the search was presumptively unreasonable and therefore unconstitutional. The majority opinion argued that a person has an expected privacy in his or her home and therefore, the government cannot conduct unreasonable searches, even with technology that does not enter the home. Justice Scalia also discussed how future technology can invade on one's right of privacy and therefore authored the opinion so that it protected against more sophisticated surveillance equipment. As a result, Justice Scalia asserted that the difference between "off the wall" surveillance and "through the wall" surveillance was non-existent because both methods physically intruded upon the privacy of the home. Scalia created a "firm but also bright" line drawn by the Fourth Amendment at the "'entrance to the house'".[1] This line is meant to protect the home from all types of warrantless surveillance and is an interpretation of what he called "the long view" of the Fourth Amendment. The dissent thought this line was "unnecessary, unwise, and inconsistent with the Fourth Amendment"[2] because according to Scalia's previous logic, this firm but bright line would be defunct as soon as the surveillance technology used went into general public use, which was still undefined.

In the dissent Justice John Paul Stevens argued that the use of thermal imaging does not constitute a search, which requires a warrant, because any person could detect the heat emissions. He argued that this could be done by simply feeling that some areas in or around the house are warmer than others or observing that snow was melting more quickly on certain sections of the house. Since the public could gather this information, Stevens argued, there is no need for a warrant and the use of this technique is not unconstitutional. Moreover, Stevens asserted that the use of the thermal imaging device was merely "off the wall" surveillance because it did not detect any "intimate" details of Kyllo's home. Finally, Stevens commented on Kyllo's trying to incorporate something as intangible, fluid and public as heat into the private sphere. He explained, "Heat waves, like aromas that are generated in a kitchen, or in a laboratory or opium den, enter the public domain if and when they leave a building."

The decision broke apart the traditional "conservative" and "liberal" wings of the court: the majority opinion was written by Scalia, joined by Souter, Thomas, Ginsburg and Breyer, while Rehnquist, O'Connor, Kennedy and Stevens dissented.

See also


  1. ^ 40
  2. ^ 41

External links

Works related to Kyllo v. United States at Wikisource

  • Text of Kyllo v. United States, 533 U.S. 27 (2001) is available from:  Findlaw  Justia  LII 
  • Background from the OYEZ project, Northwestern University
  • Transcript of oral argument
  • Brief of the Solicitor General
  • Amicus brief of the ACLU
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