X-Ray Vision

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The technology that the nine justices of the Supreme Court wrestled with last week was relatively crude: a heat-sensing gun pointed at a house in Florence, Ore., by federal agents on the lookout for homegrown marijuana. In 1992, a cop using the device had spotted a lot of excess heat coming off high-intensity grow lights. Police searched the house, found more than 100 plants and arrested one of its occupants--a small-time marijuana grower named Danny Kyllo. Kyllo appealed the case all the way to the highest court, arguing that by using infrared technology to pry into his home, the government had conducted an unconstitutional search.

To the surprise of many court watchers, the majority ruled in Kyllo's favor. And the dissenting Justices in the 5-4 decision made it clear that even if they were willing to accept "off-the-wall" technologies like infrared guns--which can pick up signals only from the outside of a building--they viewed with alarm newer "through-the-wall" devices that can see inside.

Through the wall? Yes, indeed. A whole new generation of surveillance technology has been developed since Kyllo was busted. Some of these new devices are already turning up at airports, prisons, border crossings and crime scenes. And while none of them is quite up to the standards of, say, Superman, they can see through clothing and peer into private homes well enough to raise thorny privacy issues for all of us. Among the leading contenders:

X-RAY VISION Today's preferred technology for looking through things is the same one Wilhelm Roentgen used to photograph the bones in his wife's hand in 1895, although the newest X-ray devices are considerably more powerful. Last September, for example, the U.S. Customs Service placed an order worth more than $25 million for 15 truck-based X-ray inspection systems made by American Science and Engineering, Inc., in Billerica, Mass. Using a technique in which images are made from X rays scattered back from objects (rather than passing through them), AS&E's systems can spot--with extraordinary clarity--guns, drugs, plastic explosives and other contraband, even when hidden, say, in the middle of a fully packed banana truck. One of the company's products, called BodySearch, reveals ghostly images of weapons and whatever else--including genitals--might be hidden underneath your clothes.

RADAR FLASHLIGHTS Gene Greneker, a radar expert at Georgia Tech, was fiddling with a radar gun he had developed for monitoring marksmen and archers during the 1996 Atlanta Olympics when he noticed something odd: whenever someone walked on the other side of his laboratory wall, a deflection appeared on the radar screen. One thing led to another, and now Greneker is trying to smooth out the final kinks in his Radar Flashlight, a device that looks like an oversize hair dryer but can penetrate 8-in.-thick nonmetal doors and walls. When radar waves encounter moving objects, like a hostage taker's nervous pacing or heaving diaphragm, the motions are translated into a bar of LED lights in which the height of the bar corresponds with the amount of movement in the room. In more sophisticated radar detectors, like the prototype made by Time Domain Corporation of Huntsville, Ala., the crude LED display is replaced by dancing circles and colored blobs that show both the location and trajectory of moving objects on the other side of an opaque barrier.

BEYOND BAR GRAPHS Some firms are pushing for yet more clarity. Using shorter-wavelength radar waves measured in millimeters, not centimeters, Millivision in Amherst, Mass., makes a device that goes well beyond colored blobs. "What we are doing is real imaging," says Richard Huguenin, chief technology officer. "You see a picture." Actually, it's more like a shadow. The human body, as it turns out, naturally emits millimeter radiation that goes right through clothes. So anything blocking that emission, such as a concealed gun or wallet, shows up as a shadow in the images produced by Millivision's prototype scanners. Huguenin acknowledges the privacy concerns, but he argues that the technology's public-safety benefits outweigh them. "You can tell the boys from the girls" with his device, says Huguenin, "but you usually can anyway."

The Supreme Court was clearly more troubled by the privacy issues than Huguenin. The majority opinion explicitly used the heat-detector case to draw what Justice Antonin Scalia called a firm, bright line blocking the use of this and future imaging technologies to peer into the home or any other place where an individual might have a reasonable expectation of privacy.

But the court also left the police a couple of outs. The first is to get a search warrant. If the cops have good reason to peer inside a house, they can always go to a judge and get permission--just as they do today with a wiretap. The second is to wait for the technology to become ubiquitous. If everybody owns a through-the-wall imager, the court suggested last week, then nobody can reasonably expect any privacy anywhere, even at home.