The Wikipedia page on fair use (http://en.wikipedia.org/wiki/Fair_use) states: “In United States copyright law, fair use is a doctrine that permits limited use of copyrighted material without acquiring permission from the rights holders. Examples of fair use include commentary, search engines, criticism, parody, news reporting, research, teaching, library archiving and scholarship. It provides for the legal, unlicensed citation or incorporation of copyrighted material in another author's work under a four-factor balancing test.” The exact wording of U.S. Code § 107 is described in Appendix 1. In plain speak, provided that the ultimate objective is academic or educational, parts of a manuscript can be used to display errors, or to make commentary or criticisms. Since post-publication peer review (PPPR), a tool used to correct the literature through critical analysis of the already published literature (Teixeira da Silva 2015a), often relies on the use of visual aids to make comparisons between duplicated material, to facilitate understanding by the readership, fair use thus plays a central role in PPPR, and forms part of the road map to achieve structured, reliable, understandable and sound PPPR (Teixeira da Silva 2015b). Scientists who wish to engage in PPPR are reticent, as they do not know their legal or ethical limitations. Thus three key questions arise, and answers are provided to address these. 1) Is fair use copyright infringement? No, since it is an exception to copyright law, within reasonable limits. 2) Is fair use duplication or partial duplication (of text, tables, or figures)? No, since the source is fully described and permission is not required to reuse parts of copyrighted material for academic purposes, within reasonable limits, such as PPPR. 3) Is fair use unethical? If used correctly, while referencing the original source of the copyrighted material, there are no ethical constraints. According to the DCMA (http://www.dmca.com/FAQ/Fair-Use), fair use is now widely accepted around the world, and thus the limited academic use of copyrighted material from any country would thus not constitute copyright infringement. It is expected, however, that as more literature becomes challenged, that some publishers may turn to DCMA take-down notices to try and silence the voices of academic criticism.