What is Trespass?
To trespass, in law, is a transgression or wrongful act, including in its broadest sense any injury to the person, property, or other legally protected interest of another. A trespass is a civil injury, as distinguished from a violation of criminal law which is called a crime, felony, or misdemeanor. It is often defined as the doing of an unlawful act or of a lawful act in an unlawful manner, and has been held to include many torts, such as battery, conversion, deceit, libel, negligence, and alienation of affections. A mere omission to perform a duty is not a trespass.
In its narrower and more common usage, trespass means an unauthorized invasion of real estate in the possession of another. The legally protected interest affected by trespass is that of exclusive possession, rather than ownership, of land. In general, any entry on land without premission is a trespass, whether or not force is used and whether or not damage is done. A trespass need not be committed in person, but may be effected by causing or permitting an inanimate object (such as a projectile, water, or tree) to pass over or fall upon another's land. A wrongful entry below the surface of land, as well as on or above the surface, is a trespass.
Under modern case law and statutes, however, flights of aircraft at a reasonable altitude are not considered trespassory. Causing a third person to make an unauthorized entry may constitute a trespass. An intentional intrusion on land without the possessor's consent is not a trespass if made pursuant to some privilege conferred by law. Among those so privileged are remaindermen and reversioners making inspections or repairs, persons entering in order to avert a public calamity or disaster, and citizens or police officials making arrests. An officer entering lawfully may later become a trespasser by the performance of a wrongful act.