(Kyllo v. United States was decided by the United States Supreme Court in 2001)
In 1991, a federal agent came to suspect that an individual named Danny Lee Kyllo was growing marijuana in his home. Indoor marijuana growth typically requires the use of high-intensity lamps. Early one morning in January 1992, the federal agent and his partner parked outside of Kyllo’s home armed with a thermal-imaging device. A thermal-imaging device can detect relative amounts of infrared radiation; virtually all objects emit such radiation, even though it is not visible to the naked eye. At the time, these devices were used by law enforcement but not generally by the public.
From their car across the street, the federal agents used the thermal-imaging device to scan Kyllo’s home. The imager converted the radiation from the home into images based on relative degrees of warmth – black was cool, white was hot, and shades of gray indicated other differences in heat. In that respect, the imaging device operated somewhat like a video camera showing heat images. The agents’ scan of Kyllo’s home took only a few minutes. It showed that the roof over the garage and a side wall of Kyllo’s home were relatively hot compared to the rest of the home. Also, his home was substantially warmer than neighboring homes within his triplex.
Based on the scan, the federal agents concluded that Kyllo was using high-intensity lamps to grow marijuana in his home. The information from the thermal-imaging scan contributed to a judge’s decision to issue a warrant to search the inside of Kyllo’s home. The agents who searched the home found more than 100 marijuana plants inside. Kyllo was charged with one count of manufacturing marijuana in violation of a federal law. At his trial, he asked the district court to suppress the marijuana evidence because the agents had conducted the thermal-imaging scan without a warrant. He argued that the thermal-imaging scan itself was a search.
Unless an established exception applies, the Fourth Amendment requires the government to have a warrant in order to conduct a search or seize evidence. Was the thermal-imaging scan of Kyllo’s home a “search?”