By their nature, trees can grow and do damage via their branches or roots. There has been a great deal of litigation on this issue, and the rules are well established. First, ownership of the tree is governed by location of its trunk. If the tree trunk stands entirely on one owner’s land, he or she owns the tree, even if its roots go under the border or its branches over the border. Civil Code Section 833. If, on the other hand, a tree trunk stands, in part, on the land of several owners, the tree is owned in common by all of them. Civil Code Section 834. Commonly owned trees cannot be cut down without the consent of all owners.

If a tree is owned by one party, but extends its roots or branches into the property of another party, those encroaching roots or branches may be considered a nuisance by the law. If a tree owned by one party drops branches on the house of a neighbor, the owner of the tree may be liable for damages. The party whose land is encroached upon by the roots or branches may sue for money damages, sue for injunction or simply trim the roots or branches him or herself. Bonde v. Bishop (1952) 112 Cal. App. 2d 1. The landowner whose property is encroached upon may not, however, go onto his or her neighbor’s land and cut down a tree, whose trunk is entirely on his or her neighbor’s property. Flick v. Nilson (1950) 98 Cal. App. 2d 683.

Earlier California court decisions suggested that there was an absolute right by an adjoining landowner to cut roots or branches, which encroached on his or her property. A recent decision limited that logic. In Booksa v. Patel (1994) 24 Cal. App. 4th 1786, one neighbor cut the encroaching roots of an adjoining landowner’s tree. The owner of the tree believed that the roots were not damaging the neighbor. The owner further asserted that the way in which the roots were cut was careless, and forced the tree to be cut down entirely, which was not necessary.

The owner of the tree sued for damages. The trial court ruled for the neighbor, holding that the right to cut encroaching roots was absolute and subject to no limits. The Court of Appeal reversed this decision. It held that encroaching roots cannot be cut, unless they are doing damage, and it further held that the way in which they are cut has to be reasonable.