Question: I have a backyard with many trees. The branches of some of my trees overhang my neighbor’s yard and others overhang the pedestrian walkway which is adjacent to my backyard. Do I have to cut off any branches that protrude from my backyard?
Answer: There are a number of factors to take into consideration. The first issue is height. The Mishna (two Mishnayos on Bava Basra 27B) rules that if the branches are above a specified height the branches can remain. The height specified in these Mishnayos is the height at which the branches interfere with the neighbor or the public. Thus, the underlying principle which can be derived from these Mishnayos is that if the branches do not interfere with the neighbor’s use of his property or the public’s use of their property, the branches can remain. Not only you do not have to cut down the branches but no one else may cut them down either. The rationale is that one may use another person’s, or public, property to the extent that others don’t suffer any loss as a result of that use. This principle is stated explicitly by the Rivash (end of Responsa 455).
In case the branches do interfere with the neighbor’s use of his property, then the neighbor has the right to cut off the branches.
The issue now is who is responsible for trimming the branches. This is an issue which is discussed by Rishonim. For example, the Rambam (Shecheinim 10, 8) writes, “One whose neighbor’s branches protrude over his property may trim any branches which are lower than the length of a stick above his plow.” It should be noted that the Rambam is quoted verbatim by the Shulchan Aruch (155, 26). Similarly, the Tur (155, 41) records a responsa of a Gaon that one who wishes to tar his roof may cut off the branches of his neighbor’s tree which interfere with the tarring of his roof. The question was whether he was even permitted to trim the branches since they preceded his building of an additional floor. Once again we see that the one who must do the trimming is the one who needs the branches trimmed and not the owner of the tree. This is specifically stated by the Meiri (Commentary to Bava Basra 27B).
The reason for this ruling is a basic principle that governs neighborly relations. A person may not act in a manner which directly damages his neighbor (called “girei delei“-literally to shoot arrows). However, he may act in a way which only indirectly results in damage to his neighbor. Thus, the Mishna (Bava Basra 25B) rules that a person may plant a tree even if the roots or branches will eventually protrude under and above the neighbor’s field because it takes time until the damage occurs. Since the damage is considered to be indirect, it becomes the responsibility of the victim to avoid being damaged.
The final situation which requires consideration is where the branches overhang public property. The first point that should be mentioned is that sometimes they needn’t be trimmed. The Gemara (Bava Basra 60A) records that one of the Ammoraim did not trim his branches because no one complained and so he assumed that the public was pleased with the overhang because of the shade it gave. In case the public is not pleased, the Mishna records that any branches that interfere with the public’s use of their thoroughfare may be trimmed. In the time of the Mishna this meant that if the branches interfered with one who rode a camel they could be trimmed even if the owner of the tree did not desire that they should be trimmed. What remains undetermined is who must trim them: the public or the owner.
The reason there may be a difference between branches which interfere with a neighbor’s use of his field and the public’s use of their thoroughfare is that often the chachomim (See Gemara Bava Basra 24B) shifted the responsibility away from the public and onto the individual. Their reasoning was based on human behavior. Often no one will look after the public’s welfare whereas an individual will generally ensure that his rights are not violated. In order to ensure that the public’s rights will not be violated they shifted the onus from the public onto the individual. Thus the question is whether they did so in this situation as well.
There are several indications from the Gemara that here as well they distinguished between where the victim was an individual and where it was the public. For example, the Gemara (Bava Basra 60A) records that Rav Yanai told someone whose branches overhung public property that he must trim his branches.
Additional proof may be brought from a similar situation. In the time of the Gemara (See Bava Metsia 107B) it was necessary to maintain a path along the banks of rivers in order to allow people to walk on the shore and pull a boat along. Often it was necessary to trim the branches of trees whose branches obstructed the path. The Gemara criticizes one of the Amoraim (Rabbo bar Rav Huno) for not having cut his trees. This implies that it is the tree-owner’s responsibility. This is further indicated by the expression used by the Rambam when (Nizkei Momon 13, 26) he records this halocho and is written explicitly by the Meiri (Commentary to Bava Metsi’o 107B).
In conclusion the answer to your question is:
Concerning the trees which overhang your neighbor: Those which don’t interfere with your neighbor’s use of his property may remain. Your neighbor has the right to trim those branches which do interfere with his use of his property.
Concerning trees which overhang public property: If no one complains, you can assume that the public doesn’t mind, and you needn’t trim them at all. If the public does complain and they truly interfere, you should trim them yourself. If you fail to do so, any person has the right to trim them even against your will.