Are thermal detection devices used by law enforcement an invasion of privacy?

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When a confidential informant advised Pennsylvania law enforcers that a suspected drug dealer was growing large quantities of marijuana in his home using artificial lights, a drug task force used a thermal detection device to confirm the report. The device, called a WASP, distinguishes appreciable and noticeable amounts of heat. Using the device, the task force found an unexplainable amount of heat coming from the basement area of the suspect’s home. Because the task force did not have to intrude onto the suspect’s property to use the WASP device, it did not request or obtain a search warrant.

The trial court found that vented heat or heat waste are not issues as to which residents expect privacy. The Pennsylvania Superior Court then heard the issue on appeal and disagreed.

Noting that thermal imaging can measure all temperatures across the exterior surface of a structure, creating an infrared picture of the heat sources and heat-generating activities inside a home, the Superior Court found the use of such devices to be an unconstitutional intrusion. The court noted that a person may suspect that his movements in a car may be tracked or that his suitcase might be inspected during his public travel. However, citizens do not expect that their activities within their own homes will be subject to high technology surveillance. Had the task force requested and secured a search warrant for the use of the WASP device, the Superior Court may not have been troubled by the issue.

It is likely that the technological tools available to law enforcers will be subjected to continual constitutional challenges. Where the use of innovative equipment is accomplished without search warrants, Pennsylvania courts will continue to focus on issues of privacy in determining the propriety of police conduct.