We begin our analysis, in Part I, by considering the rule against plagiarism as a corol¬lary to a complex social norm I refer to as the "norm of attribution." Under this norm, one is permitted to copy another's words or ideas if and only if he attributes them to their original author. One who violates the norm of attribution commits plagiarism, and, if discovered, faces a range of possible sanctions. While the rule against plagiarism has considerable normative strength (most especially in particular sub-communities), however, it is not without ambigui¬ties. Among other things, it is not always easy to distinguish between writing that is copied with the intent of being passed off as the plagiarist's own and writing that is merely subject to the inadvertent "influence" of earlier work.
Green, Stuart P. "Plagiarism, Norms, and the Limits of Theft Law: Some Observations on the Use of Criminal Sanctions in Enforcing Intellectual Property Rights." Hastings Law Journal Vol. 54, No. 1,(2002): 171.