If the trunk extends to both sides of the property boundary (even if it has grown that way after starting completely on one side), then the tree is shared and neither neighbor can take steps to prune, treat, or cut down the tree without the other's consent, and both are responsible for it. When the trunk of a tree is located directly on the boundary line between properties, the tree is called the boundary tree and is assumed to be owned by both neighbors. In the case of neighboring trees, both neighbors benefit by agreeing on how to care for the tree and sharing the costs of pruning and care. Both neighbors must consent to the removal of the tree and both have legal responsibility for its care.
When the trunk of a tree is divided by the property lines of two or more people, it is called the boundary tree. In the case of a boundary tree, all owners own the tree and share responsibility for it.
Felling treeswithout the consent of all owners is illegal. In the rare event that the tree trunk is right in the middle of the boundary between you and your neighbor, then it will be a mutual responsibility to take care of the tree.
Each of you must be careful not to take any action that could damage the tree as a whole, such as digging up the roots or placing dangerous chemicals that could kill it. When wandering tree roots damage a neighbor's property, financial responsibility for the damage lies with the tree's owner. In most states, the annoying neighbor can dedicate himself to pruning the tree or cutting the roots himself, and has no lawsuit against the tree owner. However, you must take care that any maintenance you do on the branches of the tree does not damage the rest of the tree.
However, disputes over trees near the property boundary can involve large sums of money, especially if the tree is damaged or dies. Trees whose trunks are within the boundary of your property are considered part of your property and, therefore, your responsibility. And according to NOLO, there is case law that grants damage to homeowners if their neighbors have pruned a tree to the point where the tree is no longer pleasing to the eye. If your neighbor took reasonable care to maintain the tree branch, and the tree branch didn't seem to a reasonable person to be threatening to fall, probably not.
You want to prune the branches of the offending trees, but the tree is located on the property border between your house and your neighbor's house. These regulations allow you to sue your neighbor to force your neighbor to remove a tree (or the branches of a tree) that is blocking your panoramic view. Even if the tree trunk is on your neighbor's property, anything from the tree that falls on your property is your responsibility. On the other hand, if the tree was not properly maintained and your neighbor knew or should have known that the tree or its branches posed a threat, then your neighbor could be responsible for the damage caused.
In most cases, a whole tree (trunk, branches and roots) is owned by the person who controls the land where the tree was originally planted, usually the owner.