Florence, Ore. Nine years ago, members of a narcotics task force stopped in the early morning darkness in front of Danny Lee Kyllo's house and scanned it with a thermal imaging device.
The task force was investigating whether Kyllo's neighbors were growing marijuana. But when they trained the thermal scanner on Kyllo's home, it showed indications of excessive heat.
Based on that scan, electricity records and an informant, investigators got a search warrant to enter Kyllo's home, where they found more than 100 marijuana plants growing under high-intensity lights.
Kyllo contends that his Fourth Amendment rights were violated because the officers did not obtain a search warrant to scan his house with the thermal imager. He pleaded guilty to a federal charge, but reserved the right to appeal the search.
Today, the U.S. Supreme Court will hear oral arguments on his appeal.
Though Kyllo faces only a month in jail if the high court rules against him, experts say the case is likely to bring out an important new definition of the legal limits on police searches of the most sacred of all private places the home.
"In many ways, it is a question that is both scientific and metaphysical," said professor David Schuman of the University of Oregon School of Law. "Does this (scanner) take someone from outside (a home) and put them in or take information from inside and take it out?"
"If the government is free to use technology to look inside our homes, there really won't be anything left of the right to privacy," said Dave Fidanque of the Oregon chapter of the American Civil Liberties Union.
In its brief, the government compared the thermal scan to a police officer watching a house from the outside, which does not require a warrant.
"Thermal imagers do not literally or figuratively penetrate the home and reveal private activities within," the U.S. Solicitor General's Office wrote. "Unlike a hypothetical sophisticated X-ray device or microphone that could perceive activity through solid walls observations that would amount to searches a thermal imaging device passively detects only heat gradients on exterior surfaces."
In past rulings, the high court has allowed police to proceed without a warrant when they put a radio beacon in a car to track its location, send a helicopter over private property to see inside a greenhouse, or use a flashlight to illuminate a darkened car.
However, the court has required police to get a warrant before placing a microphone inside a house or on the outside of a telephone booth.
Defense attorney Kenneth Lerner argues that thermal imaging amounts to looking behind closed doors.
"Since we don't permit police to break into people's homes, should we permit them to use technology to accomplish the same thing?" he said.
"The public justifiably expects that the walls of our homes sanctify a zone of privacy against the government, and represent physical barriers that assure our privacy," Lerner wrote in his brief.
Lower court rulings have been mixed. State supreme courts have come down on both sides.
Kyllo, 35, said he hopes his case will serve to protect people's privacy. "There's an old saying that a man's home is his castle," he said. "I know what I done was wrong. But I know what they're doing is wrong."