The use of relatively short direct quotes from a published work does not usually require permission from the copyright holder as it typically falls under the “fair use” provision. However, extensive quoting of text from a copyrighted source can constitute copyright infringement, whether the appropriated text is properly enclosed in quotation marks or correctly paraphrased, even if a citation is provided according to established scholarly conventions. Obviously, the same applies if the material is plagiarized outright. Moreover, the reader should note that intellectual or artistic work does not need to be published in order to be copyrighted. In fact, the moment the work becomes final it is automatically copyrighted. Thus, instances of plagiarism, whether from a published article or even an unpublished manuscript, can also constitute copyright infringement, though, of course, copyright infringement does not always constitute plagiarism. For example, if I were to quote extensively and with proper citation beyond the limit dictated by the publisher of the work from which I quoted, I would be in violation of that publisher’s copyright, but the infraction would not constitute plagiarism as I am letting the reader know, by my use of quotations and a citation, that the material being used is not mine.
Iverson, et al., (2007) cautions the reader that the amount of text that can be taken from a copyrighted source without permission depends on its proportion to the entire work. However, the reader should also note that some publishers, such as the APA, have established word limits for borrowing text. Given the above considerations, it should then be clear that extensive plagiarism and self-plagiarism may also qualify as copyright infringement because the copyright of the plagiarized or self-plagiarized content may be held by the publisher; not by the author. This would certainly be the case if the original article were published in a journal owned by one publisher and the second article were to appear in a journal owned by a different publisher both of which require that authors transfer the copyright of their papers to the publishers. One should note that not all publishers require that authors transfer their copyright to them.