Trespass, in Law, is a physical interference with the person or property of another. However innocent the act, if it be voluntary, a legal wrong is done. Thus, if pursued by a wild beast you deliberately take refuge in another man's house, you commit a trespass; but if you rush there in mere blind fear, you do not. Again, if you drive in so careless a manner as to hurt any one, though unintentionally, this is a trespass. If animals or, indeed, any chattels are on a man's land doing damage, they may be seized and impounded till compensation be made. This remedy is called distress damage feasant. It is similar to distress at common law—e.g. there is no power of sale. If a dog worry cattle or sheep, the owner is liable since 1863. Formerly it was necessary to prove scienter—i.e. knowledge by the master of the animal's vicious disposition. Scienter must still be proved in other cases, and generally when animals, not savage by nature, do hurt—a legal doctrine quaintly parodied in the vulgar saying, that the dog is entitled to his first bite. Even in complete absence of real injury an action for trespass will lie, for, says Lord Denman, those rights are an extension of that protection which the law throws round the person. A verdict of a farthing damages is, however, the frequent and appropriate compensation for injury without damage (injuria sine danno).
As will be seen, there are various kinds of trespass: (1) trespass to goods, which consists in damaging them physically, as asportation—i.e. carrying them away; (2) trespass to the person, which is either battery, assault, or false imprisonment. Battery is an active attack on any one. Assault (q.v.) is an attempted battery; both are criminal offences as well as civil wrongs. False imprisonment is usually classed among the latter. It consists in depriving a man of his liberty without lawful excuse. Compelling any one to submit by the exhibition of superior force, though no actual violence be used, is a wrong of this nature. If a constable intervene, the question is, did he do so of his own initiative, or at the prompting of a third party? In the second case only, even if the arrest be illegal, can the third party be held liable for the false imprisonment. Trespass to the person may be justified on the ground that a man was acting in self-defence, that it was necessary to stop a breach of the peace, to apprehend a felon, or to assist police-officers in the execution of their duty, and that the person arrested was dangerous to himself and others. Various acts give power to arrest those found committing certain specified misdemeanours.
As regards trespass to land, since a plaintiff must succeed by the strength of his own, not by the weakness of his adversary's case, bare possession is a good title as against a wrong-doer; so the occupier may turn out an intruder, using, upon his refusal to depart peaceably, as much force as is necessary. If the possessor be forcibly turned out, he may forcibly re-enter, even though outer doors be broken open to effect the purpose. But this must be done immediately, otherwise the owner, though entitled to possession, will, if he use violence, render himself criminally liable under the statutes of Forcible Entry. In making a distraint for rent, or in levying an execution, but not in executing criminal legal process, it is a trespass to break open the outer door. Although the general rule is that any entry on another's land is a trespass, yet in certain cases of necessity an entry is excused—e.g. to abate a nuisance, or to prevent the spread of fire. A customary right of recreation or right of way will excuse what would otherwise be a trespass. Cut glass or spikes on a wall are allowable as a defence against intruders; but not man-traps or spring-guns (except inside a dwelling-house), at least since 1827. Even before that a trespasser could recover for damages so done to him, unless he had notice of the existence of the engines in question. The mere act of trespassing on another's land is not a criminal offence, but by statute it is when in pursuit of game, on railways, on places where explosives are stored or animals afflicted with contagious disease are confined. Besides the remedies for trespass—viz. forcible expulsion and an action for damages—an injunction may be granted, even for a bare trespass, since the Judicature Act of 1873. The law of the United States is based on the English law.
The term trespass, in Scots law, is borrowed from that of England. It is restricted to trespass to land. The law on the subject is generally the same as in the rest of the United Kingdom. The Trespass Act, 1865, provides a summary form of punishment for those who camp upon open land, or lodge in premises or enclosures without leave. Against mere trespassers an interdict may be obtained. See RIGHT OF WAY, POACHING, GAME-LAWS.