[schoen]

Interestingly, the U.S. Supreme Court surprised many people in 2001 by putting limits on government use of infrared imaging. (They didn't ban it entirely, but they said that it would be regulated as a search, normally requiring permission from a judge.)

https://en.wikipedia.org/wiki/Kyllo_v._United_States

This means that police may not be able to routinely use imaging technologies, including active radars, to look through the walls of people's homes.

(Interestingly, this is a way in which police now have fewer powers than the general public, since in most places there are no laws preventing you as a civilian from using infrared imaging to look at someone's house.)

[keithg]

Presumably citizens are allowed because they don't have the power to charge & convict you of some alleged crime. If the citizen's imagery were somehow brought into a legal matter, then it would be up to the judge to determine its legality. Conversely and unfortunately, law enforcement and government seem to enjoy a defacto legality until someone says otherwise. By limiting their use of this technology, hopefully it mitigates the defacto and clandestine nature of it, bringing it at least to a level of awareness during legal proceedings.