Legal Question in Real Estate Law in Illinois

This is something you should consider taking up with your local code enforcement people if they can keep your anonymity. Removing trees isn't cheap. 4 large trees taken down with permits (and stumps ground...) could run into the thousands. Be careful about throwing stones, even if you are getting sticks at you. That aside, as a neighbor you can suggest that his insurance may not cover him in case of damage because he's neglecting the situation, and in a worst case scenario where one of the trees falls, he could become personally liable without coverage.