Docket No. 99-8508

FOURTH AMENDMENT
Is the Thermal Imaging of a Home an Unreasonable Search, a Reasonable Search, or Not a Search at All?

By William P. Weiner
William P. Weiner is a professor of law at Thomas M. Cooley Law School in Lansing, Mich.

Case at a Glance
The police scan a home with a thermal imager, a camera-like device that records and depicts infrared radiation. It displays escaping heat. While the local utility company might use such a device to determine whether the homeowner needs new windows or better insulation, in this case the police use it to help them develop probable cause to believe that marijuana is being grown inside the home. Is this high-tech observation controlled at all by the Fourth Amendment?

Argument Date: February 20, 2001
From: The Ninth Circuit

Both technology and increasing technological advancement have become central features of modern life. Some of this technology has clear and obvious application to law enforcement, yet it can threaten personal privacy. In this case, the Supreme Court faces a conflict between the technology of thermal imaging and the privacy of the home.

Issue
Is the use of a thermal imaging device to detect heat that is either within a home or radiating from it a “search” under the Fourth Amendment?

Facts
Just over nine years ago, on Jan. 16, 1992, a member of the Oregon National Guard pointed an Agema 210 thermal imager at Danny Lee Kyllo’s home. The imager operates like a camera. It gathers infrared radiation just as a camera gathers visible light. The imager converts the infrared radiation into a visible image displayed on a screen. Warm areas appear white, cool areas are displayed as black, and in-between areas look gray on the screen. The Agema 210 imager shows heat patterns in a relative sense. It does not measure temperature in degrees like a thermometer does.

The guardsman’s thermal scan showed high heat levels coming from the garage roof and also from a side wall. It also showed that Kyllo’s house, part of a triplex, was giving off more heat than the other houses in that triplex. Based on prior observations, the guardsman felt that the heat patterns were similar to those of other marijuana growing operations. This information was combined with other information. For example, police subpoenaed Kyllo's utility records, and these revealed high electrical use at Kyllo’s home. U.S. Bureau of Land Management agents then obtained a search warrant.

When officers executed the search warrant on Jan. 27, 1992, they found marijuana in Kyllo's attic. They seized the marijuana and the growing equipment. They also arrested Danny Kyllo. After his indictment for manufacturing marijuana, Kyllo moved to suppress the seized evidence. The trial court (the U.S. District Court for the District of Oregon) denied this motion and ruled that thermal imaging was not a search for Fourth Amendment purposes. Because the Fourth Amendment was not violated, the results of the thermal imaging could be used to develop probable cause for the search warrant.

This case’s appellate history is both mixed and lengthy. The Ninth Circuit first vacated the conviction and remanded the case to the trial court for an evidentiary hearing. The issue was the intrusiveness of thermal imaging. After a substantial consideration of the capabilities of thermal imaging--how it works, what can it “see,” and how this technology is advancing--the district court decided that thermal imaging was not a Fourth Amendment search.

The Ninth Circuit then reversed, finding that there was indeed a search. The court again remanded the case, this time for a determination of whether there was enough evidence, absent the results of the thermal imaging, to support probable cause for the search warrant. The Ninth Circuit then reheard the case. Meanwhile, one of the original three judges retired and was replaced. On rehearing, Kyllo’s 2-1 victory became a 2-1 defeat, with the Ninth Circuit now agreeing with the trial court that thermal imaging is not a Fourth Amendment search.

The United States Supreme Court then granted certiorari.

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