Orin Kerr writes:

In Kyllo v. United States, 533 U.S. 27 (2001), the Supreme Court held that it violated the Fourth Amendment to direct an infrared thermal imaging device at a home without a warrant to determine the home’s temperature. This post asks whether that result is still good law. I realize that probably sounds a bit nutty at first, as Kyllo is only a few years old. But Kyllo deliberately adopted a test designed to let the result change with social practice . This post asks whether changing social practices already allow the police to use thermal imaging devices without a warrant.

I’ll look at the problem in three steps. First, I’ll explain the relevant Fourth Amendment test from Kyllo. Second, I’ll explain how technology and social practice have changed in the eight-and-a-half years since the Kyllo decision. And third, I’ll put the pieces together and ask whether Kyllo’s result remains good law. My bottom line: I’m not really sure, but there is a decent case to be made that the police can now use thermal imaging devices without a warrant consistently with Kyllo.