I have a similar situation in Missouri... My neighbor's tree branch fell on another neighbor's car. They claim it was hanging over the property line of our apartment and was therefore the responsibility of our landlord to take care of. It's pretty clear the branch went straight up and was not over the property line. The only reason I seriously believe they may be liable is because another tenant told me this happened 3 years ago when another giant branch smashed another car. There seems to have been reasonable notice that the tree was a danger... Anyone have any thoughts?