Defamation is the act of harming the reputation of another by making a false statement to a third person. Although the distinction is generally not made in caselaw, defamation may divided into libel or slander. Libel means to defame someone in a permanent medium, usually in writing. Slander is defamation in a transitory form, normally speech. Although libel and slander are for the most part governed by the same principles, there are two important differences: (1) Libel is not only a tort, but may also be a criminal offense. Slander is strictly a civil injury. (2) Damages for slander--unlike those for libel-- are not presumed and thus must be proved by the plaintiff.

Defamation is almost impossible to challenge with a § 1983 action. The reason for this is that § 1983 actions are for violations of civil rights granted in the Constitution. Since defamation is a matter of state law, it is not a sufficient basis for bringing a § 1983 suit. In the rare case that a § 1983 action is held sufficient for defamation, it is because (1) the plaintiff suffered injury to his reputation from an official’s false statements, and (2) the plaintiff has also suffered burden or alteration of status or rights. The harmful effects of an injured reputation alone will not suffice as a “burden or alteration of status or rights.” A recent case exemplifies the concept of immunity for defamation, and the difficulty in maintaining a § 1983 suit. In Sadallah v. Utica, 383 F.3d 34 (2nd Cir. 2004), the court stated that defamation is an issue of state law, not of federal constitutional law, and therefore provides an insufficient basis to maintain a § 1983 action. The mayor made allegedly defamatory remarks about the physical condition of a restaurant, and the restaurant owner sued. Even assuming the mayor’s statements really were defamatory, the court would not allow for damages against the city and the mayor: “The state- imposed burden or alteration of status must be in addition to the stigmatizing statement. Thus, even where a plaintiff's allegations would be sufficient to demonstrate a government- imposed stigma, such defamation is not, absent more, a deprivation of a liberty or property interest protected by due process.”

Examples of burdens that satisfy the second requirement are the deprivation of the plaintiff’s property, and the termination of a plaintiff’s government employment.