Conversion (law)

Conversion is an intentional tort, defined as taking property with the intent to exercise ownership over it in a way that conflicts with the rightful owner’s right to possession. In England and Wales, it is a strict liability tort. Its criminal law counterparts include larceny, theft, and criminal conversion, though in jurisdictions that recognize it, criminal conversion is considered a lesser offense than theft or larceny.

Questions about joint ownership in business arrangements like partnerships typically fall under equity and do not qualify as conversion. Traditionally, conversion occurs when a chattel is lost, then found by someone who appropriates it for their own use without legal authority. It also applies when goods are bailed for safekeeping and are later misused or misappropriated by the bailee or a third party.

As a purely civil wrong, conversion differs from both theft and unjust enrichment. Theft is always an act inconsistent with another’s rights and also constitutes conversion, but not all conversions are thefts because conversion does not require dishonesty. Conversion also differs from unjust enrichment: in a claim for unjust enrichment, the person holding another’s property can raise a change of position defense, arguing they unwittingly used up the assets. For conversion, there must always be an element of voluntarily dealing with another’s property in a way inconsistent with their rights.

The elements of conversion are: intent to convert the tangible or intangible property of another to one’s own possession and use, followed by the actual conversion of that property. Another formulation states that a claimant must show a tortious conversion of the chattel, a right to property in it, and a right to immediate possession that is absolute, unconditional, and not dependent on performing some act.

A common medieval example involved bolts of cloth bailed for safekeeping, which the bailee or a third party took and made into clothes for their own use or sale. Other examples include cutting down trees on someone else’s land and removing them without permission, or taking someone else’s furniture without consent and putting it into storage. The use of a patient’s body parts after surgical removal to treat his leukemia raised conversion questions, addressed in the case of *Moore v. Regents of the University of California*.

Conversion has been called a fascinating tort that has largely escaped legal writers’ attention, with its literature often overlapping with that of trover. Other sources define it as a distinct act of dominion wrongfully exerted over another’s personal property, inconsistent with or in defiance of the owner’s title or rights, without consent or lawful justification. A conversion occurs when a person acts in reference to another’s personal property in a way that amounts to appropriating it for themselves. The action likely developed because English law had no equivalent to the Roman law *rei vindicatio*, a property protection action where a claimant could simply say “that’s mine.” Early cases appear in 1479, referencing an even earlier action on the case where the defendant “converted” goods by changing their character, such as making clothes from gold cloth.

Otherwise, conversion originated in the common law action in trover, as a branch of action on the case. The earliest cases are probably lost, but likely involved finders of lost goods who did not return them but used or disposed of them. A new writ was needed to cover the gap between trespass (for wrongful taking) and detinue (for wrongful detention). By 1554, the claim in conversion had become standardized in *Lord Mounteagle v. Countess of Worcester*, where the plaintiff lost goods, the defendant found them, and instead of returning them, “converted them to his own use.”

There is a distinction between trover and conversion. Trover resolved the old procedural problem of wager of law, which had become a form of licensed perjury and made detinue unattractive for honest plaintiffs suing dishonest defendants. Wager of law allowed testimony from many witnesses unrelated to the litigation, resembling champerty and maintenance. Because trover sidestepped these issues, it was expanded into many forms. The legal device used was to treat the allegation of losing and finding as a fiction, seen in several 17th-century cases. The defendant was not permitted to deny losing and finding, so the only issues litigated were the plaintiff’s right to possession and the conversion as fact. With losing and finding no longer essential, trover became the standard remedy for any interference with a chattel, entirely replacing detinue and largely supplanting trespass to chattels. In 1756, Lord Mansfield stated in *Cooper v. Chitty* that whenever trespass for taking goods would lie—that is, where the taking is wrongful—conversion also lies.