I can feel your pain. Obviously the neighbor doesn't care. Call the cops every time there is a an altercation. If you can catch the dogs, ask that the sheriff impound the dogs. When his dogs attack yours, take them to the vet every time and send him the bill. Make the neighbor go through the hassle of dealing with the cops every time. If the neighbor tries to do anything to your dogs, well that's a whole 'nother story.

I'm a dog lover but just can't stand aggressive dogs and stupid people.