The right of reproduction and the right of adaptation are the main rights infringed upon through actions of “plagiarizing” or “copying”. When the plaintiff claims that the defendant has plagiarized his works, the plaintiff needs to prove that the works meet the protective elements of the Copyright Act, and that the defendant has engaged in reproduction, whether tangibly or intangibly. If there is no direct evidence for the latter, the plaintiff should present evidence to prove that the defendant had access to the works, and that there is substantial similarity between the expression of the defendant’s and plaintiff’s works. The so-called “substantial similarity” means that the defendant’s works cite substantial and important expression of plaintiff’s works, measured from both qualitative and quantitative perspectives. The judgment of substantial similarity needs to take into account the nature of the plaintiff’s works. For example, the content, which the plaintiff claims to be plagiarized, is a factual work based on material in the public domain. Since it is difficult to fabricate, its space for elaborating is limited and its information resources may overlap. Therefore, it calls for a stricter standard for the elements of “substantial similarity”; it not only needs to be similar literally, but also adopts a higher quantitative requirement. On the contrary, if the content belongs to a more creative genre such as fiction, science fiction or poem, the literal requirement could be lowered. The judgment of substantial similarity also has to do with the number of options to express the same idea in different ways, the nature of the similar parts, etc.

Meaning of Plagiarism, Criteria and Elements of Substantial Similarity