“Plagiarism, which many people commonly think has to do with copyright, is not in fact a legal doctrine. True plagiarism is an ethical, not a legal, offense and is enforceable by academic authorities, not courts. Plagiarism occurs when someone — a hurried student, a neglectful professor, an unscrupulous writer — falsely claims someone else’s words, whether copyrighted or not, as his own. Of course, if the plagiarized work is protected by copyright, the unauthorized reproduction is also a copyright infringement.” Paul Goldstein, Copyright’s Highway 12 (1994).
“That the supporting evidence for the accusation of plagiarism may on occasion be elusive, insufficient, or uncertain, is not the same as thinking that the definition of plagiarism is uncertain. The gray areas may remain resistant to adjudication without being resistant to definition. It may be perfectly clear what constitutes plagiarism (‘using the work of another with an intent to deceive’) without its being clear that what faces us is truly a case of this.” Christopher Ricks, “Plagiarism,” in 97 Proceedings of the British Academy 149, 151 (1998).