上述三个单词均有类似渎职的含义，因而三个单词的定义经常被人混淆。严格说来，三个术语的区别很大，这种区别在判定代理人对第三人的责任时尤为重要[1]。misfeasance应为“作为不当”，指不当履行某人本应合法行使的行为（the improper performance of some act which one may lawfully do)，如在履行合同时犯有过失，其有主动不当行为导致他人损害的含义(active misconduct working positive injury to others) [2]。而 nonfeasance为“不当不作为”，指对某人本应履行的职责采取不作为的态度（the omission of an act which one ought to do)，为消极或未采取对他人的保护（passive inaction or a failure to take steps to protect others from harm)[3]。相比之下，malfeasance 则为“不当作为”，指行使了某人本完全不应当行使的行为（the doing of an act which one ought not to do at all) 。

[1]“There is a distinction between nonfeasance and misfeasance or malfeasance；and this distinction is often of great importance in determining an agent’s liability to third persons. ”Cf. The Publisher's Editorial Staff, Black's Law Dictionary, abridged 6th edition, at p. 729，West Publishing Co. (1991).

[2] Id. at p. 691.

[3] Cf. Daphne Dukelow, The Dictionary of Canadian Law, at p. 688, Thomson. Professional Publishing Canada (1991).

[4] Cf. The Publisher's Editorial Staff, Black's Law Dictionary, abridged 6th edition, at p. 729, West Publishing Co. (1991).