In Kyllo v. United States (2001), Justice Scalia introduced a test to determine whether the use of a thermal imaging camera, a novel technology that could not be known at the time of the founding, constitutes a search for purposes of the Fourth Amendment.

“The Fourth Amendment is to be construed in the light of what was deemed an unreasonable search and seizure when it was adopted, and in a manner which will conserve public interests as well as the interests and rights of individual citizens.” Carroll v.United States, 267 U.S. 132, 149 (1925).

Where, as here, the Government uses a device that is not in general public use, to explore details of the home that would previously have been unknowable without physical intrusion, the surveillance is a “search” and is presumptively unreasonable without a warrant.

In 2001 when this case was decided, the thermal camera was not in common use. However, this has changed. I blogged in 2013 that DARPA was working on shrinking thermal cameras to a handheld device.

Today, the Wall Street Journal reports that you can add a thermal camera to your iPhone or Android with a $250 accessory.

Heat-vision cameras have been used widely in many industries for decades: Soldiers find targets through heat-vision rifle sights, police mount them on helicopters to search for people on the ground and contractors use the sensors to look for cold air seeping into homes. Now you can buy a simple smartphone attachment to reveal the widely varying temperatures of the people and things around you.

The author recommends the Flir One:

The other big difference, one that ultimately makes Flir the better choice for most people, is that the Flir One actually has two cameras on board, a low-resolution traditional one in addition to the thermal. The real-time image on your phone is a composite of the two camera feeds, with high-contrast “edges” from the full-color camera providing much-needed definition to all of the thermal blobs. This is most helpful when you go back to look at your images later. In many cases, you’d otherwise have no clue what you’re looking at. …

But Flir currently has the edge in software. When browsing its in-app gallery of still photos, you can swipe between the full-color image and the thermal one. Seek gives you a live side-by-side view, using the built-in iPhone camera, but the images don’t line up well, and the tools Seek does offer to make use of this don’t work very well. Besides, the full-color images aren’t saved with the thermals.

So, Justice Scalia, is this is “general public use?” Maybe we can tell by how many downloads it gets in the App Store?

We’ve come a long way in the last century, as this German postcard from 1900 illustrates the X-Ray police force!

 

H/T Adam A.