Plagiarism is when an author attempts to pass off someone else's work as his or her own. Duplicate publication, sometimes called self-plagiarism, occurs when an author reuses substantial parts of his or her own published work without providing the appropriate references. This can range from having an identical manuscript published in multiple journals, to 'salami-slicing', where authors add small amounts of new data to a previous manuscript.

Plagiarism can be said to have clearly occurred when large chunks of text have been cut and pasted. Such manuscripts would not be considered for publication in an AOSIS journal. However, minor plagiarism without dishonest intent is relatively frequent, for example when an author reuses parts of an introduction from an earlier manuscript. AOSIS journal editors judge any case of which they become aware (either by their own knowledge of and reading about the literature, or when alerted by referees) on its own merits.

AOSIS is a member CrossCheck, an initiative to help editors verify the originality of submitted manuscripts. As part of this process all manuscripts are scanned and compared with the CrossCheck database.

If a case of plagiarism comes to light after a manuscript is published in an AOSIS journal, the journal will conduct a preliminary investigation. If plagiarism is found, the journal will contact the author's institute and funding agencies. A determination of misconduct will lead the AOSIS journal to publish a corrigendum linked to the original publication, with an explanation. Depending on the extent of the plagiarism, the manuscript may also be formally retracted.