"WASHINGTON (Reuters) - The U.S. Supreme Court ruled on Monday that thermal
imaging to record the amount of heat emanating from a house, a police
practice often used to help detect illegal drugs, represented a search
covered by constitutional privacy protections.

The court's 5-4 ruling was a setback for the U.S. Justice Department ,
which argued the use of a thermal imager by law enforcement officers to
detect the heat emitted from a house was not a search and was not covered
by the privacy protections.

Justice Antonin Scalia said for the court majority that when the
government uses a device not in general public use to explore the details
of a private home that would previously been unknowable without physical
intrusion, the surveillance is a search and requires a warrant."

That was ruled on just a few years ago in the U.S., and undoubtedly pissed off the DEA, because now thermally imaging someone's home is considered a search and requires a warrant. That's only in the U.S. though; I don't know how other countries have ruled, but in the U.S., you have little to fear from thermal imaging. I mean, they fly overhead and point the thermal imager at your home and see the heat from 500 1k lights, THEY have just broken the law, by remotely 'searching' your home without a warrant. Which means that anything they might discover as a consequence of the thermal imaging would be fruit from the poisonous tree and would be thrown out in court.