Kyllo v. United States 533 U.S. 27, 121 S. Ct. 2038, 150 L. Ed.2d 94 (2001)
The police suspected Kyllo of
using grow-lamps to grow marijuana inside of his home.
Realizing that grow-lamps
produce a lot of heat, the police used a thermal imaging camera to take
photos of Kyllo's house from a public street. The cameras showed an
unusual heat source. The police used this information to obtain a
warrant, entered Kyllo's home, found marijuana plants, and arrested Kyllo
for drug possession.
The thermal imaging camera
emits no beams or rays, it is a passive collection system that only
records what is naturally emanating from the target (unlike an x-ray
machine which zaps its target with x-rays).
At trial, Kyllo made a motion
to suppress on the grounds that the thermal camera represented an illegal
search of his house and was therefore a violation of the 4th
The Trial Court denied the
motion to suppress. Kyllo appealed.
The Appellate Court upheld the
conviction. Kyllo appealed.
The US Supreme Court reversed
and granted the motion to suppress.
The US Supreme Court found
that thermal imaging of a home constitutes a 4th Amendmentsearch and may be done only
with a warrant.
The Court found that the
general public does not have access to thermal imaging cameras, and
therefore there is a presumptive expectation of privacy.
In a dissent it was argued
that while thermal imaging cameras are not common, there were other ways
in which the general public could observe thermal emissions from a house
(for example, snow melting on a roof), and therefore there was no
violation of the 4th Amendment.
Compare to United States
v. Karo (468 U.S. 705), where it was
suggested that if something could be done without technology, but was
easier with the technology, it would be ok to use the technology.
The dissent further suggested
that the thermal camera only measures the temperature of the outside wall
of the house, it says nothing about what is inside. Therefore there is no
Technically, since the outer
wall temperature is directly related to the temperature inside the house,
the thermal camera does give
information about what is inside.
Why is it that the color of
your house is clearly public information, but the temperature of your
house is private?
Sense enhancing technologies
have the potential of reducing the core protection that a home is private,
so the Court wanted to draw a sharp line about what was going to be ok as
It is likely that through
the wall technology is coming in the near future.
What if, in the future, the
general public starts wearing x-ray specs? The court suggests that if
something like that happens, then it will no longer be reasonable to
assume that your home is private.