The basic defenses applicable to ordinary individual defamation, of truth, privilege (including fair comment), and consent, also apply to group defamation. Most past group defamation cases have held that language including all members of a given group,or positively identifying the plaintiff, must be used. Tort actions have been upheld when small groups are defamed; tort claims are generally disallowed in the defamation of large groups unless the public readily recognizes the defamation as being directed at one individual. A number of "group-hate" statutes have been enacted by various states, making it a criminal offense to defame a class of citizens. Defenses based on truth are difficult to establish because of the statistical complications encountered in groups of large numbers. The best defense to these statutes appears to be based on fair comment and the constitutional guarantees of the First Amendment.
Richard J. Quigg, Defenses to Group Defamation Actions, 13 Clev.-Marshall L. Rev. 102 (1964)