Not really. It still comes down to a matter of proof. The neighbor that is supposedly eavesdropping can deny everything and the case is dead in the water. This is not enough to get a search warrant because it IS possible that the two of you are conspiring against the other neighbor (not saying that this is the case, only that it is a reasonable possibility) or that a third party overheard your conversation ... or that one or both of you told someone else who in turn told someone who told the other guy. There's just no proof.

I would think that the most the police are likely to do (if they don't blow it off entirely) is to knock on the fellow's door and ASK if he has been listening in on your conversations. If they feel particularly eager they may even ask if they can take a look around inside. But, if he says, "No" and denies commiting an illegal act, the officers will shrug and be gone in a heartbeat.

Yes, I did understand your post the first time. Your inference is reasonable ... but there are other possible explanations even if they are not true. It is the possibility of these other explanations that would prevent a search warrant or any involved investigation.

Unless someone sees him mounting a parabolic mic or wiring the neighborhood for sound, it's going to take more than this to get anyone excited.

If there is already some kind of civil action going on then your friend may want to let his attorney know about this turn of events.

- Carl