Kyllo v. United States Case Brief

Facts of the case

A Department of the Interior agent, suspicious that Danny Kyllo was growing marijuana, used a thermal-imaging device to scan his triplex. The imaging was to be used to determine if the amount of heat emanating from the home was consistent with the high-intensity lamps typically used for indoor marijuana growth. Subsequently, the imaging revealed that relatively hot areas existed, compared to the rest of the home. Based on informants, utility bills, and the thermal imaging, a federal magistrate judge issued a warrant to search Kyllo’s home. The search unveiled growing marijuana. After Kyllo was indicted on a federal drug charge, he unsuccessfully moved to suppress the evidence seized from his home and then entered a conditional guilty plea. Ultimately affirming, the Court of Appeals held that Kyllo had shown no subjective expectation of privacy because he had made no attempt to conceal the heat escaping from his home, and even if he had, there was no objectively reasonable expectation of privacy because the imager did not expose any intimate details of Kyllo’s life,only amorphous ‘hot spots’ on the roof and exterior wall.

Why is the case important?

The police obtained evidence of a marijuana growing operation inside the defendant, Kyllo’s (the “defendant”) home, by using a thermal imaging device from outside the home. The police used the device to gather evidence to support issuance of a search warrant for the home.


Does the use of a device by the government to obtain evidence from a constitutionally protected area without physical intrusion constitute a search under the Fourth Amendment of the Constitution?


Where police obtain information about the inside of a home without physical intrusion, using a device not normally used by the public, the police action constitutes a Fourth Amendment search and is presumptively unreasonable without a warrant.


The Supreme Court of the United States reversed the appellate court’s judgment and remanded the matter for further proceedings. The Court concluded that obtaining information regarding the interior of a home, which could not otherwise have been obtained without physical intrusion into a constitutionally protected area, such as Kyllo’s private residence, constituted a search, at least where the technology was not in general public use. Since thermal imaging technology was not in general public use, such a surveillance was a search and was presumptively unreasonable without a warrant. Whether the search warrant was supported by probable cause without the surveillance evidence was for the trial court to determine in the first instance.

  • Advocates: Michael R. Dreeben Department of Justice, argued the cause for the United States Kenneth Lerner Argued the cause for the petitioner
  • Petitioner: Kyllo
  • Respondent: United States
  • DECIDED BY:Rehnquist Court
  • Location: Kyllo’s Home
Citation: 533 US 27 (2001)
Argued: Feb 20, 2001
Decided: Jun 11, 2001
Kyllo v. United States Case Brief