Originally Posted by mugaliens

The legal terminology is a "reasonable expectation of privacy."

Your neighbor, talking on his phone, as a reasonble expectation of privacy. That no longer holds, however, if he's out in his backyard, talking on the phone loudly, or worse, using a speakerphone, and you're in your backyard, laying in the sun, sipping tea, and taking all of it in.

. . .

On the other hand, the jury's still out on whether or not he has a reasonable expectation of privacy is he's broadcasting in the clear. Personally, I think it's the same as a neighbor talking loudly in his backyard, but some would disagree.