Trespass to chattels is a tort whereby the infringing party has intentionally interfered with another person's lawful possession of a chattel. The interference can be any physical contact with the chattel in a quantifiable way, or any dispossession of the chattel (whether by taking it, destroying it, or barring the owner's access to it). As with all intentional torts, it is "actionable per se" so no proof of damage is required.
The origin of the concept comes from the original writ of trespass de bonis asportatis . As in most other forms of trespass, remedy can only be obtained once it is proven that there was direct interference regardless of damage being done, and the infringing party has failed to disprove either negligence or intent.
In some common law countries like the United States and Canada, a remedy for trespass to chattels can only be obtained if the direct interference was sufficiently substantial to amount to dispossession, or alternatively where there had been an injury proximately related to the chattel. (See Restatement (Second) of Torts, 1965.)
Damages from a trespass claim are limited to the actual harm sustained by the plaintiff (which can include economic loss consequent on the trespass - e.g. loss of profit on a damaged chattel). In cases of dispossession, the plaintiff is always entitled to damages if they can prove the dispossession occurred, even if no quantifiable harm can be proven.
A related tort is conversion, which involves an exercise of control over another's chattel justifying restitution of the chattel's full value. Some actions constitute trespass and conversion; in these cases, a plaintiff must choose which claim to make based on what amount of damages they seek to recover.
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