ASHINGTON, Feb. 20 — The Supreme Court wrestled today
with how to apply the Fourth Amendment's ban on unreasonable
searches to a technological development the Constitution's
framers most likely did not have in mind: a thermal imaging
device that the police can use from outside a home to detect
patterns of heat being generated from inside.
The specific question in the hourlong argument was whether
use of a thermal imager by the police is a search that, no less
than an actual entry into a house, requires a warrant. The
underlying question was how the Constitution should take account
not only of changing technology but also of society's changing
understanding of technology's threat to privacy.
Under the court's precedents, the Fourth Amendment protects
only those expectations of privacy that are "reasonable."
Someone who conducts business in front of an open living room
window, for example, may be deemed to have forfeited any
reasonable expectation of privacy.
In the case today, Kyllo v. United States, No. 99-8508, the
lawyer for an Oregon man convicted of growing marijuana in his
home argued that the police engaged in an illegal search by
using a thermal imager to detect the distinctive heat pattern
made by the high- intensity lights that are often used for
marijuana cultivation. The police used the information as the
basis for obtaining a warrant to search the house.
People have a reasonable expectation of privacy in what goes
on behind the opaque walls of their homes, the lawyer, Kenneth
Lerner, told the justices.
What the thermal imager captures "really is molecular
information that migrates through our walls," Mr. Lerner said,
adding, "If we are now saying that we can capture that kind of
information without a warrant, we can reduce our whole world to
that type of wave and molecule, and our walls mean nothing."
But Michael R. Dreeben, a deputy solicitor general arguing
for the government, said people did not have a reasonable
expectation of privacy "in the heat that's on the exterior
surface of their walls."
"Heat loss is an inevitable feature of heat in a structure,"
Mr. Dreeben said. "That's why there is an insulation
industry."
Justice Stephen G. Breyer objected that the expectation of
privacy "is not in heat loss, it's in what is going on in the
house."
Justice Breyer said the question was whether "you have a
reasonable expectation that the kind of thing you're doing in
the house will not be picked up by somebody out of the house,
not a law enforcement officer, but just ordinary people."
"Where you're walking in front of the window," he continued,
"the answer is no. Where you're walking in front of the window
and people pick it up with binoculars — every bird-watcher has
binoculars. Where they're picking it up with flashlights — every
Boy Scout has a flashlight. Who has a heat thermal device?
Nobody, except a few."
Justice Breyer said it was at least open to argument whether
people had a valid expectation of privacy that when they took a
long hot bath, that fact would not be disclosed to the world by
the use of a thermal imaging device.
Mr. Dreeben replied that while the device can detect heat,
"it will not tell you what's going on inside the house."
Justice Breyer was not satisfied. "It'll just tell you it's
hot in there, which happens to be just the thing they want to
know," he said. "They want to know if it's hot or if it's
cold."
Mr. Lerner, representing the defendant, Danny Lee Kyllo, also
came in for tough questioning.
"Why don't your reasonable expectations of privacy include
technology?" Justice Antonin Scalia wanted to know. Inasmuch as
there are thermal imagers in the world, why not expect people to
guard against them just as "you pull your curtains if you want
privacy because you know people have binoculars," Justice Scalia
said.
"The burden," Mr. Lerner said, "really is improperly placed
on the citizen to anticipate what type of technology the
government may come up with."
Justice David H. Souter asked: "Are you saying, in effect,
that if thermal imaging becomes very common and every school kid
has a $5 thermal imager, that at that point it really would be
unreasonable not to expect that the government was going to use
it to figure out what's going on in the house?"
Mr. Lerner said the court would then have to step in just as
it has to prevent indiscriminate use of wiretapping, a
technology that everyone knows is available yet is still
regarded as an unconstitutional invasion of privacy except in
limited circumstances.
Mr. Lerner's client entered a conditional guilty plea while
challenging the use of the thermal imager. He first won his case
before the United States Court of Appeals for the Ninth Circuit,
in San Francisco, but the appeals court changed its mind and
issued a new opinion after one of the original members of the
three- judge panel retired. Mr. Kyllo served a month in jail on
his marijuana conviction.
The court issued a decision today in another Fourth Amendment
case, ruling 8 to 1 that police officers who have probable cause
to search a home for easily destroyed contraband can keep a
suspect from entering his own home during the brief time it
takes to get a search warrant.
The decision, Illinois v. McArthur, No. 99-1132, overturned a
ruling by an Illinois appellate court that found the detention
to be a seizure that violated the Fourth Amendment. Justice
Breyer wrote the decision, concluding that the brief detention
met the Fourth Amendment's test of reasonableness.
Justice John Paul Stevens dissented, saying the Illinois
court correctly "placed a higher value on the sanctity of the
ordinary citizen's home than on the prosecution of this petty
offense."
The offense was possession of drug paraphernalia and a small
quantity of marijuana, both misdemeanors under Illinois
law.
