Trespass to Chattels

Trespass to chattels is one of the older property torts in the Anglo-American common law tradition, descending from the medieval writ of trespass de bonis asportatis. It protects a possessor's interest in tangible movable property ("chattels") against intentional interference that falls short of the more serious tort of conversion. Where conversion typically results in a forced sale remedy (the defendant pays the full value of the item), trespass to chattels usually yields only damages for the actual harm caused, the diminution in value, or the loss of use during the period of interference.

The Restatement (Second) of Torts § 217 defines the tort as intentionally dispossessing another of a chattel, or using or intermeddling with a chattel in the possession of another. Under § 218, liability attaches only if the possessor is dispossessed, the chattel is impaired in condition, quality, or value, the possessor is deprived of use for a substantial time, or bodily harm results.

The doctrine acquired modern significance through its application to digital and networked property. In Intel Corp. v. Hamidi (Cal. 2003), the California Supreme Court held that sending unwanted emails to Intel's servers did not constitute trespass to chattels absent actual damage to the system. By contrast, CompuServe Inc. v. Cyber Promotions (S.D. Ohio 1997) and eBay v. Bidder's Edge (N.D. Cal. 2000) applied the tort to spam and to automated web scraping that burdened server capacity. These cases shaped early debates over bot traffic, scraping, and the boundaries of computer-misuse law alongside the federal Computer Fraud and Abuse Act.

For researchers, the tort is useful as a lens on how analog property concepts are stretched to govern digital infrastructure, and how courts balance access, automation, and possessory rights. It rarely appears in international instruments but features prominently in U.S., U.K., and Commonwealth tort syllabi.