Just to follow up with a brief excerpt:

Does one have the right to eavesdrop on one’s own property? It is a hot summer evening, and the house that I own has no air conditioning. I therefore park myself outdoors under one of the eaves and hope that a breeze will supply some relief from the heat. While there, I overhear a conversation that takes place in my living room: the windows of the living room are open, because the occupants also are hoping for a breeze. Have I violated the right to privacy of the living room’s occupants? It is possible that the occupants did not want me to hear what was being said, but the space underneath the eave where I parked my body belonged to me, and parking myself there violated no one else’s right: I was using property that was rightfully mine in the manner that I saw fit. If the occupants of the living room had not wanted me to hear the conversation, they could have closed the windows (actually, because I owned the windows, the occupants would have needed my permission to open or close them).

Now let us consider the case of the eavesdropper who eavesdrops on someone else’s property. An eavesdropper parks himself without my permission under one of the eaves of my house, and he overhears some of the conversation of the parties inside the house. The fact that he overhears a conversation is beside the point. The eavesdropper has violated my right to property, because he is using my property without my consent, and that violation would have occurred even had he not overheard the conversation—even if there had been no conversation. What the second eavesdropper is guilty of is not violating someone else’s right to privacy; he is guilty of trespass, which itself is a form of theft. A right to privacy either is subsumed under the right to property, or it simply does not exist.