Conversion is an intentional tort consisting of "taking with the intent of exercising over the chattel an ownership inconsistent with the real owner's right of possession". In England and Wales, it is a tort of strict liability. Its equivalents in criminal law include larceny or theft and criminal conversion. In those jurisdictions that recognise it, criminal conversion is a lesser crime than theft/larceny.
Examples of conversion include: 1) Alpha cuts down and hauls away trees on land s/he knows is owned by Beta, without permission or privilege to do so; and 2) Gamma takes furniture belonging to Delta and puts it into storage, without Delta's consent (and especially if Delta does not know where Gamma put it). A common act of conversion in medieval times involved bolts of cloth that were bailed for safekeeping, which the bailee or a third party took and made clothes for their own use or for sale.
Many questions concerning joint ownership in enterprises such as a partnership belong in equity, and do not rise to the level of a conversion. Traditionally, a conversion occurs when some chattel is lost, then found by another who appropriates it to his own use without legal authority to do so. It has also applied in cases where chattels were bailed for safekeeping, then misused or misappropriated by the bailee or a third party.
Conversion, as a purely civil wrong, is distinguishable from both theft and unjust enrichment. Theft is obviously an act inconsistent with another's rights, and theft will also be conversion. But not all conversions are thefts because conversion requires no element of dishonesty. Conversion is also different from unjust enrichment. If one claims an unjust enrichment, the person who has another's property may always raise a change of position defense, to say they have unwittingly used up the assets they were transferred. For conversion, there always must be an element of voluntarily dealing with another's property, inconsistently with their rights.
Elements of conversion
The elements of conversion are: 1) Intent to convert the tangible or intangible property of another to one's own possession and use, 2) The property in question is subsequently converted.
In another formulation, it has been stated that one claiming conversion must show a tortious conversion of the chattel, a right to property in it, and a right to immediate possession which is absolute, unconditional, and not dependent upon the performance of some act.
History of conversion
Conversion has been described as a fascinating tort, albeit one which has largely eluded the attention of legal writers. The literature frequently laps over into that of trover. Other sources define conversion as a distinct act of dominion wrongfully exerted over another's personal property in denial of or inconsistent with his title or rights therein, or in derogation, exclusion, or defiance of such title or rights, without the owner's consent and without lawful justification.
A conversion occurs when a person does such acts in reference to the personal property of another as amount, in view of the law, to his appropriating the property for himself. The action probably developed because there was no equivalent form of action in English law to the Roman law rei vindicatio. This was an action in protection of one's property, whereby a claimant could simply allege in court "that's mine!". Early cases of conversion are to be found in 1479, where reference to an even earlier action on the case is made when the defendant "converted" the goods by changing their character, making clothes out of gold cloth.
Otherwise, conversion had its origin in the common law action in trover, as a branch of action on the case. The earliest cases are most likely lost. These probably involved cases when the finder of lost goods did not return them to the rightful owner, but used them himself or disposed of them to someone else. It became necessary to invent a new writ which covered the gap between action in trespass which lay for the wrongful taking of a chattel, and detinue which lay for its wrongful detention.
The claim in conversion had become standardized by 1554 in the case of Lord Mounteagle v Countess of Worcester , . The plaintiff was in possession of certain goods, he casually lost them, the defendant found the goods and did not return them, but instead "converted them to his own use."