According to FindLaw, a neighbor has a right to plant trees up to the property line. As long as the tree trunks are in his yard, there is very little a person can do. If the tree trunks are on the property line, they are considered boundary trees and legally belong to both sides. A person does not have a legal right to remove the trees unless his neighbor agrees.
The law regarding trees and tree-trimming is quite specific, according to FindLaw. Any tree that is planted on a neighbor's property belongs to him, and a person can be found liable for up to three times the replacement value if he cuts it down or kills it in any way. Since the value of a mature tree may be anywhere from $500 to $2,500, and ornamental specimens may cost $20,000 or more, damaging a neighbor's trees could be a very costly mistake.
Neighbors do have rights regarding tree-trimming, says FindLaw. Any portion of a neighbor's trees that overhang into a person's yard may be trimmed to the property line at that person's expense. He may not enter his neighbor's yard without his permission, however, nor do anything to damage the tree. Additionally, that person is not entitled to pick or eat any fruit from his neighbor's trees without his neighbor's permission. He is responsible for removal of any leaves, sticks or debris that fall on his property. The law views these as natural products, so the neighbor does not need to remove them or pay to have them removed from the yard.
Issues that occur when a tree is a nuisance or causes property damage are less clear cut, according to FindLaw. For example, if a neighbor's tree falls down and damages a home or car, that person may be entitled to recover the cost of any repairs. He must first prove, however, that his neighbor did not exercise reasonable care to maintain the tree. If the neighbor did, the court is unlikely to award any damages because the accident was an act of God.