Misfeasance in public office is a cause of action in the civil courts of England and Wales and certain Commonwealth countries. It is an action against the holder of a public office, alleging in essence that the office-holder has misused or abused their power. The tort can be traced back to 1703 when Chief Justice Sir John Holt decided that a landowner could sue a police constable who deprived him of his right to vote (Ashby v White). The tort was revived in 1985 when it was used so that French turkey producers could sue the Ministry of Agriculture over a dispute that harmed their sales.

Generally, a civil defendant will be liable for misfeasance if the defendant owed a duty of care toward the plaintiff, the defendant breached that duty of care by improperly performing a legal act, and the improper performance resulted in harm to the plaintiff.

In theory, misfeasance is distinct from nonfeasance. Nonfeasance is a failure to act that results in harm to another party. Misfeasance, by contrast, is some affirmative act that, though legal, causes harm. In practice, the distinction is confusing and uninstructive. Courts often have difficulty determining whether harm resulted from a failure to act or from an act that was improperly performed.