Conversion is an intentional tort under common law that protects an owner's right to possess and control their chattels (movable personal property). It occurs when a defendant assumes dominion over the plaintiff's property in a manner inconsistent with the plaintiff's ownership rights — for example by taking, destroying, withholding, selling, or substantially altering it. Unlike trespass to chattels, which compensates for minor interference, conversion treats the interference as so serious that the defendant is effectively required to pay the full market value of the item, as if a forced sale had occurred.
The classic elements are: (1) the plaintiff's ownership or right to immediate possession; (2) the defendant's intentional act of dominion or control; (3) interference serious enough to justify full damages; and (4) resulting harm. Intent refers to the act itself, not to wrongdoing — a good-faith purchaser of stolen goods can still be liable. Mistake or ignorance of the true owner is generally no defense.
In the United States, conversion is codified in the Restatement (Second) of Torts §222A, which lists factors courts weigh to distinguish conversion from lesser interference: extent and duration of control, the actor's intent to assert a right inconsistent with the owner's, good faith, harm done, and inconvenience caused. English common law traces the action to the old writ of trover.
Typical remedies include damages measured by the property's fair market value at the time and place of conversion, plus consequential losses. Some jurisdictions also allow replevin (recovery of the item itself) as an alternative.
Modern disputes increasingly involve intangible property — domain names, cryptocurrency, electronic records, and trade secrets — and courts are split on whether conversion doctrine extends beyond tangible chattels. New York's Court of Appeals expanded the doctrine to certain electronic records in Thyroff v. Nationwide Mutual Insurance Co. (2007), while other jurisdictions remain more restrictive.
Example
In *Thyroff v. Nationwide Mutual Insurance Co.* (2007), the New York Court of Appeals held that an insurance agent could sue Nationwide for conversion after the company seized electronic records and customer data stored on its leased computer system.
Frequently asked questions
Theft is a crime prosecuted by the state requiring criminal intent, while conversion is a civil claim brought by the owner for damages. The same conduct can give rise to both, but conversion does not require proof of dishonest intent — even a good-faith taker can be liable.
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