I don't understand... Your neighbor knows his/her dog has killed EIGHT of your chickens and still doesn't do anything to resolve this situation??? What's wrong with that person? In my opinion, it is more than acceptable for you to react in any way you see fit at this point up to and including deadly force in regards to this dog. Of course, not sure of the legality but on my personal scale of right and wrong I don't see how this is wrong.