[8organicbits]

> It's also worth noting that in the case of incidental wifi surveillance, it's likely the plain-sight doctrine would apply

Plain-sight should mean observation with the natural human senses, and I think the courts agree. There is nothing "plain" about radio signals leaking through walls. The thermal imaging example in the article as well.

https://en.m.wikipedia.org/wiki/Aerial_surveillance_doctrine

> the drone observed “each window of Plaintiffs’ residence and outbuildings” and was “outside [law enforcement’s] visual line of sight,” violating both federal and Indiana law.

Placing a device outside a home to collect WiFi signals doesn't sound like "visual line of sight". I.E. clearly a 4th amendment search requiring a warrant.

Collecting records stored by devices that had been in the area already seems plausible, but would presumably require a legal justification to search those (warrant, consent, etc). But to my understanding, devices don't store such records.