Citation
Kyllo v. United States, 533 U.S. 27 (2001) (full-text).
Factual Background
A federal law enforcement agent suspected that marijuana was being grown in Danny Kyllo's, but he lacked the probable cause necessary to obtain a search warrant. The agent used a thermal imager to scan the residence. The imager detected infrared radiation coming from Kyllo’s house. The pattern revealed that portions of the house were hotter than the rest of the house and the neighboring homes. The agent concluded that Kyllo was using halide lights to grow marijuana. Using this and other information, the agent obtained a search warrant. Once inside Kyllo’s home, federal agents found numerous marijuana plants. Kyllo was convicted of cultivating marijuana,
U.S. Supreme Court Proceedings
Kyllo appealed on the ground that using a thermal imager without probable cause constituted an unreasonable search under the Fourth Amendment.
The Supreme Court held that the use of thermal imaging was a search as defined by the Fourth Amendment. Justice Scalia, writing for the majority, noted
| “ | 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. | ” |
However, the Court made clear that looking into a home with the naked eye from a lawful vantage point may not be a search (e.g., police on the sidewalk looking into the home through a picture window). The Court indicated that it is not a search if the police use technology to duplicate what the police would see if standing on the sidewalk. The Court added that if technology “in general public use” is used to see more than the naked eye (e.g., telescope, binoculars, etc.) then it is not a search. “General public use” was further defined as that which is generally available to the public.
However, the majority’s opinion expressed the concern that more advanced technologies could reach into the privacy of the home. The Court said that “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 Court then detailed what it had in mind:
| “ | The ability to “see” through walls and other opaque barriers is a clear, and scientifically feasible, goal of law enforcement research and development. The National Law Enforcement and Corrections Technology Center, a program within the United States Department of Justice, features on its Internet Website projects that include a “Radar-Based Through-the-Wall Surveillance System,”“Handheld Ultrasound Through the Wall Surveillance,” and a “Radar Flashlight” that “will enable law enforcement officers to detect individuals through interior building walls.” | ” |
The Court applied the Katz test and held that Kyllo had a reasonable expectation of privacy that the police would not use technology "not in general public use." The Court implied that if thermal imagers had been in common use its decision would have been different.