Suspected plagiarism

Case number:

Case text (Anonymised)

A single author submitted a paper to our journal. A similarity check revealed 48% similarity with another published paper. The published paper was by different authors—5 in total. The similarities between the papers were in the introduction, methods and discussion sections. The submitting author did not reference the published article.

We queried the corresponding author but have not received a response. 

Question(s) for the COPE Forum
• What shall we do given this circumstance? 
• Should we withdraw/reject the article and embargo the author.
• Should we contact the author’s institute without receiving any clarifications from the author?
• How long should we wait for a response from the author before reporting to the institute?


The Forum would advise contacting the author one more time, and specifically stating that if no response is received within a given time frame, then the editor will contact the author’s institution and ask them to investigate. The editor should be very clear about the date by which a response is expected. That may provide the motivation for the author to respond.

The Forum asked what is the percentage similarity that should raise concerns? This varies widely—by discipline, even by editors within the same discipline. The similarity index needs to be reviewed carefully, and experienced editors will look at all aspects of the article and the sources when deciding if there is significant overlap. Is there a minimum cut-off score below which there is no need to check for plagiarism? One study found a cut-off value of 15% to be useful (

If the editor believes that there was no malicious intent on the part of the authors, an educational approach may be appropriate—for example, if the authors are junior researchers. The editors could explain what is expected of authors in terms of attribution of text, and best practice in this area. However, the editor may not be in a position to know the intent of the authors and this would be better addressed by the institution.

The journal cannot proceed moving this article forward until some of these questions are answered. COPE would never advise banning authors because of the legal implications.