There isn't an easy or simple solution because in California, you do not have the absolute right to cut or remove branches from your neighbor's tree. Generally speaking, you are entitled to trim the branches which overhang into your property. However, in the case of Booska v. Patel (1994) 24 Cal. App. 4th 1786, the California Court of Appeal held that a neighbor does not have the absolute right to cut encroaching roots and branches so that they end at his or her property line. You must take into account the health of the tree before you start trimming, cutting or chopping. You might be liable for reasonable costs of replacing destroyed tree with identical or substantially similar tree.
Frank W. Chen has been licensed to practice law in California since 1988. The information presented here is general in nature and is not intended, nor should be construed, as legal advice for a particular case. This Avvo.com posting does not create any attorney-client relationship with the author. For specific advice about your particular situation, please consult with your own attorney.
If the neighbor's trees are causing damage to your property, then he could be held responsible for that damage. If you take matters into your own hands, you could end up being sued if you harm the trees.
Try and work it out with your neighbor.
You may need to bring a contractor and/or an arborist in to determine the amount of damage and how to stop it, and could submit a claim to your and/or your neighbor's insurance.