Peter wrote:
The laws differ in each state. Here (Maryland), the neighbor is
legally liable for any of my damages or clean-up costs if he was
negligent in ignoring a hazardous condition that would predictably
lead to my damages. For example, if a large, apparently healthy,
over-hanging branch from his tree broke off and fell into my house or
yard, he is not liable. If his tree was obviously dead and leaning
my way, I would have a case in MD. Bottom line: You need to check
your state laws if the situation cannot be resolved by a neighborly
discussion.

State laws generally do not dwell on situations such as this. They instead
rely on the common law handed down for the past eight centuries.

Drummed into my head over and over in law school was the mantra "Everything
you need to know about contract law can be encompassed by the study of three
things." These three things we Pits, Fences, and one other that I forgot.
I want to say it had something to do with mayonnaise, but I'm sure that's
not right.