Duhaime's Law Dictionary Misfeasance Definition: Improperly doing something which a person has the legal right to do. Improperly doing something which a person has the legal right to do. In Proksch v. Bettendorf, 218 Iowa 1376 (1934), the Supreme Court of Iowa adopted these words: "Nonfeasance ... means the omission of an act which a person ought to do. Misfeasance is the improper doing of an act which a person might lawfully do. Malfeasance is the doing of an act which a person ought not to do at all." To legal theorists, negligence can be arguably divided into msfeasance and, in limited cases, nonfeasance whereas malfeasance is an intentional tort. Always looking up definitions? Save time with our search provider (modern browsers only) If you find an error or omission in Duhaime's Law Dictionary, or if you have suggestion for a legal term, we'd love to hear from you!