Are trees like unruly teenagers, disobedient and rebellious? Or are they just following their instincts and their natural life cycle, when things go wrong? It could be a little bit of both and (as with the teenagers) most often the "parents" or tree owners have more than a little to do with their disruptive behavior.
People will plant the wrong trees in the wrong places. They don't mean to, they just didn't go to the right parenting classes. Monterey pines and many other species just do not belong in small back yards in Marin County. They are often shallow rooted, drop debris, including large branches and are subject to pests and diseases that can ravage them and their neighbor trees. Eucalypts are prone to whole branch failure. You do not want to be under one of them when the wind is blowing.
We have handled several such cases, two most recently, where diseased and in one case, practically dead as a doornail, trees leaned precariously over the homes of nearby neighbors.
Neighbors feared going into their own yards, and were advised by experienced tree risk assessors that the tree could easily pierce the roof. Imagine cowering in corners of your own home, having had to abandon living, dining or sleeping quarters!
Neighborly pleas, arborists' reports and even letters from attorneys fell on deaf ears. In both cases, emergency court orders were the only remedy. Luckily the orders were in place before the trees could do their damage.
So why not mediate your tree issues first, before they become costly court cases? Save time, money and maybe even your relationship with the neighbors. Often taking this route makes everyone feel more kindly toward one another, and neighbors have been known to pitch in to help pay for trimming or removal of the offending tree, maybe even replacing it with a more "friendly" species.