i. Facts: A federal agent used a thermal imaging device to detect heat emanating off of defendant’s home. The presence of increased heat sources implied the use of additional lighting for marijuana growth. The agent then obtained a warrant to search the home and marijuana was indeed found. The defendant argues that use of thermal imaging equipment is a “search” and, in the absence of a warrant, is a violation of his Fourth Amendment rights.
ii. Holding: Thermal imaging of a home constitutes a Fourth Amendment "search" and may be done only with a warrant.
iii. Reasoning: Obtaining information by sense-enhancing technology that would otherwise require intrusion into constitutionally protected areas constitutes a search, when technology is not in general public use. Furthermore, the information gathered is not visible to the naked eye and the device is capable of determining the intimate details of happenings inside the home. The home is sacred and deserves the highest standard of protection against unreasonable searches.
iv. Stevens’ Dissent: The Justice argued that any person could detect the heat emissions; this could be done by simply feeling that some areas in or around the house are warmer than others or observing that snow was melting more quickly on certain sections of the house. Since the public could gather this information there is no need for a warrant and the use of this technique is not unconstitutional. Moreover, the use of the thermal imaging device was merely "off the wall" surveillance and did not detect any "intimate" details of Kyllo's home. It was absurd of Kyllo to try to incorporate something as intangible, fluid and public as heat into the private sphere. "Heat waves, like aromas that are generated in a kitchen, or in a laboratory or opium den, enter the public domain if and when they leave a building."