Kyllo v. United States, 533 U.S. 27 (2001)

Having been enlisted in a surveillance effort led by federal law enforcement agencies investigating alleged illegal drug operations, an Oregon National Guard sergeant used a thermal-imaging device to monitor heat emissions coming from inside the home of Danny Lee Kyllo. With the aid of the device, which is able to detect heat emissions from sources that are invisible to the naked eye (for example, people standing behind doors, ovens in use, steam from hot water), the sergeant noticed considerable heat loss coming through the roof and one wall, leading him to infer that Kyllo was growing marijuana. Federal agents then acquired a search warrant for the home and charged Kyllo with multiple drug offenses.

Writing for the Court majority, Justice Antonin Scalia found that the authorities had overstepped their bounds, exceeding the normal allowance for surveillance with the naked eye and violating one of the core principles of the Fourth Amendment: ‘‘the right of a man to retreat into his own home and there be free from unreasonable governmental intrusion.’’ Of note as well, however, is the dissent written by Justice John Paul Stevens, who asserted a constitutionally significant distinction between direct observations (that is, what one might see or hear) of a private area, on the one hand, and indirect deductions, or ‘‘thought processes used to draw inferences from information in the public domain,’’ on the other.

Although Kyllo makes a strong case for the assumption of privacy within the home, the debate over what constitutes an ‘‘invasion’’ will continue, especially as law enforcement agencies draw on evermore sophisticated surveillance technology.

BRIAN K. PINAIRE

References and Further Reading

• Amar, Akhil Reed. The Constitution and Criminal Procedure. New Haven: Yale University Press, 1997.

Cases and Statutes Cited

• Kyllo v. United States, 533 U.S. 27 (2001)

See also Electronic Surveillance, Technological Monitoring, and Dog Sniffs; Privacy; Search (General Definition)