Kyllo v. United States, No. 99-8508 (argued Feb. 20)

The Fourth Amendment protects only against "unreasonable" searches and seizures. The question of when a search is unreasonable, like the question of when the police must obtain a warrant before conducting a search or seizure, has been the subject of much discussion in the courts, a trend that has only accelerated as the police seek new ways to wage the “war” on drugs.

Drug War Technology
By scanning the outside of a house with a thermal imaging device, police can determine whether there are unusual "hot spots" that may indicate the use of high-intensity grow lights, which are often used in indoor marijuana growing operations.

The question posed in this case is whether police must obtain a search warrant before using these thermal imaging devices to scan a home. Ultimately, the defendant says, the question is "whether the 4th Amendment's guarantee of personal security in your home must yield to scientific advances that make traditional barriers of privacy obsolete."

The Case Based on an informant's tip, the police looked at Danny Lee Kyllo's utility records and concluded that he was using an unusual amount of electricity. So they decided to scan his house with a thermal imaging device at 3 a.m. one January morning. The thermal imager did show a concentration of heat coming from the roof and one wall. The police used that information to obtain a search warrant, and when they searched the house, they found an indoor growing operation.

Kyllo argued that the police needed to obtain a search warrant before they could employ the thermal imaging device.

When the Ninth Circuit concluded that no warrant had been needed because the thermal scan did not amount to a search at all, Kyllo appealed to the U.S. Supreme Court. The dissent and majority opinions in the Ninth Circuit show that this case is developing into a battle of analogies. The Ninth Circuit judges compared the new thermal imaging technology to these other, more familiar situations in which they thought a reasonable person would or would not have a reasonable expectation of privacy:

• A camera
• A telescope
• Setting out the garbage
• Chimney smoke
• Putting a listening device on the outside of a phone booth

The dissent suggests that even if the current generation of thermal scanners might be crude in terms of what they can tell police about what's going on inside a house, the next generation of scanners might be far more intrusive.

More about Thermal Imaging
What is thermal imaging? Read one company's illustrated account of how thermal imaging devices work and how they have been used in other drug cases.

In Kyllo, the Ninth Circuit Court of Appeals concluded that thermal image scans are not a "search" at all within the meaning of the Fourth Amendment.

Read the Ninth Circuit's opinion upholding the police's decision to employ thermal imaging technology without first obtaining a search warrant.

The defendant, a homeowner whose house was searched after a thermal image scan identified "hot spots" that could be created by the heat given off by an illegal indoor marijuana growing operation, has appealed to the Supreme Court. Ultimately, he argues, the issue is "whether the Fourth Amendment's guarantee of personal security in your home must yield to scientific advances that make traditional barriers of privacy obsolete."

More about the Case

Read a feature article about this case from Preview of United States Supreme Court Cases.

Read the Supreme Court's decision.

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