Copyright laws require that courts consider at least four factors in determining whether a quotation or close paraphrase of another's unpublished work without permission falls under "fair use." Several cases involving "fairuse" are discussed.
Karen Burke LeFevre,
The Tell-Tale “Heart”: Determining “Fair” Use of Unpublished Texts,
55 Law and Contemporary Problems
Available at: https://scholarship.law.duke.edu/lcp/vol55/iss2/9