Legal Question in Real Estate Law in California

Re: Fallen tree responsibility

If the trunk of a tree was growing on the property line, it is a joint responsibility, as the tree would be considered jointly owned.

If the tree was growing on the property of X it is X's tree, and when it fell onto Y's property, it created a trespass by X to the land of Y, and X is responsible for the cost of removal.

I believe a judge would expect both neighbors to cooperate and coordinate as to access to the site, methods used, choice of contractor, etc., since the removal process itself will almost necessarily involve what would technically be further trespassing unless each gives consent.

In very unusual cases, it could be possible that the collapse of the tree was partially the fault of the neighbor trespassed against by its fall; for example, by creating an unstable soil condition by excavation or release of too much water. Such conditions might result in a reversal of liability from X to Y.