Antonin Scalia

“ 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. [3] The dissent’s reliance on the distinction between “off-the-wall” and “through-the-wall” observation is entirely incompatible with the dissent’s belief, which we discuss below, that thermal-imaging observations of the intimate details of a home are impermissible. The most sophisticated thermal imaging devices continue to measure heat “off-the-wall” rather than “through-the-wall” ”

“ The dissent offers no practical guidance for the application of this standard, and for reasons already discussed, we believe there can be none. The people in their houses, as well as the police, deserve more precision. [6]
We have said that the Fourth Amendment draws “a firm line at the entrance to the house,” Payton, 445 U.S., at 590. That line, we think, must be not only firm but also bright–which requires clear specification of those methods of surveillance that require a warrant. ”

“ The Agema Thermovision 210 might disclose, for example, at what hour each night the lady of the house takes her daily sauna and bath–a detail that many would consider “intimate”; and a much more sophisticated system might detect nothing more intimate than the fact that someone left a closet light on. ”

“ This case presents the question whether the use of a thermal-imaging device aimed at a private home from a public street to detect relative amounts of heat within the home constitutes a “search” within the meaning of the Fourth Amendment.
I In 1991 Agent William Elliott of the United States Department of the Interior came to suspect that marijuana was being grown in the home belonging to petitioner Danny Kyllo, part of a triplex on Rhododendron Drive in Florence, Oregon. Indoor marijuana growth typically requires high-intensity lamps. ”