When someone enters the property of another without permission, or legal authority, he or she is trespassing. Trespassing law is a part of both civil and criminal codes in the United States, but this is not always true in other countries. For example, in the United Kingdom, trespassing law is most often a civil matter, with a few exceptions, and property owners cannot always rely on the police to enforce trespass laws.
Trespassing does not have to be a matter of one person walking onto someone's property: Building an addition on a home that crosses a property boundary line, dumping garbage into a neighbor's yard, or parking in another's driveway all can qualify. Animals, such as dogs, can also trespass on a neighbor's property, making the pet-owner liable for the pet's conduct.
In the United States, a property owner is generally obligated to enforce trespassing law on his or her private property. If a neighbor builds onto his property or routinely uses the property for storage, walking, or vehicle parking, the owner risks losing his or her rights over his property, or even the property itself. If a property owner wishes to come to an understanding with a neighbor or anyone else who wants or needs to enter or build on the owner's property, the property owner can enter into a written agreement with that individual that sets out the terms of the encroachment. This agreement can include a time frame along with other terms that can protect the property owner's rights.
Hunters should be aware that in some regions, trespassing law prescribes harsher penalties for someone carrying a firearm. Laws may also protect a hunter against a charge of trespassing if the hunter enters private property in pursuit of a dead or wounded animal.
A property owner, or his or her employee, can use reasonable force to protect his property against trespassers in both the United States and the United Kingdom. However, the definition of "reasonable" can vary, and a homeowner who uses force, particularly deadly force, against a trespasser can be subject to criminal and civil liability. For example, using a booby trap to discourage trespassers is generally against the law. Shooting at a neighbor's pet who has not posed a threat to the safety of the property owner is also likely to be frowned upon by law enforcement and the courts. Calling upon law enforcement and using the civil courts is likely a safer way to resolve a conflict with a trespasser.