It's important to know the fencing laws in the state where you live. In some states, it's the owner's responsibility to pen livestock in with fences. In other states with open range laws, the property owner must fence unwanted animals out. Regardless, every state has rules and regulations about fence ownership and who is responsible for its upkeep.
Many states have fencing laws requiring landowners with livestock to fence-in their animals. The fence-in concept traces its roots to English Common Law. Whether or not there is a fence separating a boundary, each landowner must be responsible for his own livestock. Landowners must build a fence to keep large livestock such as horses, cattle, sheep, goats and hogs on their property. Some states include dogs as well. If the animal gets out of the confinement, whether through a broken fence or a gate negligently left open, the owner is still responsible for any damage.
In a fence-out state, if the property owner doesn't want any stray animals on his property, it's his responsibility to keep them out. In states that allow open-range feeding of livestock, the fence-out rule is often in place. The fence-out rule protects homesteads and properties from herds of animals as they forage for grasses and food. If a property owner doesn't fence animals out of his crops, the owner of the roaming livestock isn't liable if the animals get into the crops and devour them.
The Right-Hand Rule
Most states apply the right-hand rule when it comes to fence ownership and maintenance whether fence-in or fence-out rules apply. To determine the owner's portion, he must stand on his property and look at the fence. The right half of it is his, and the left half is the neighbour portion. If the neighbour doesn't have livestock, the property owner that does have livestock builds and maintains the entire fence. The fence builder leaves an accounting of the cost of the fence at the county court house for future reference. If the non-livestock owning party decides at a later date to buy some livestock and run them against the fence, he then has to pay his half of the fencing costs to his neighbour based on the recorded costs. Although it's permissible to have a gentlemen's agreement on the fence ownership, having the details written into both property deeds is preferable.