Kyllo v. United States

Suspecting Kyllo (defendant) was growing marijuana in his home using high-intensity grow lamps, police used a thermal-imaging device from the street outside his house to scan for the heat those lamps would produce; the scan showed part of the house was significantly hotter than the rest, and police used that finding to obtain a warrant, ultimately discovering over 100 marijuana plants inside. Kyllo moved to suppress the evidence from the search, the court denied his motion, and he entered a conditional guilty plea preserving his right to appeal; the Ninth Circuit affirmed the denial, and the Supreme Court granted certiorari.