I was recently asked to review a paper (for a very reputable journal). In the cover letter, it says

"This paper has been checked with turnitin to ensure there is no similarity to other papers."

I haven't seen this before (although I have limited reviewing experience). Is this normal? Or does this indicate something strange about the author?

I've never checked any of my own papers for plagiarism. Should I?

EDIT: Also, why would you mention this in the cover letter?

  • 5
    It is a sort of reflection in response to the modern plagiarism related hysterics. No, it is not usual. Yet. Commented Nov 18, 2015 at 16:53
  • 2
    It is very common for editors to check for plagiarism before sending them out for review. Commented Nov 18, 2015 at 17:02
  • 1
    It happens sometimes that in a paper where several authors contributed chunks of text one of the authors behaved dishonestly with the others not aware of it. Perhaps the corresponding author is trying to make sure this didn't happen.
    – Miguel
    Commented Nov 19, 2015 at 6:11

3 Answers 3


I've never put such an assertion in one of my own cover letters, and would find it very strange to do so.

  • It's assumed that I should be behaving honestly and avoiding both plagiarism and self-plagiarism. Saying: "really, I'm not plagiarizing!" just makes me wonder why the person felt they needed to say anything.
  • If I'm not behaving honestly, why wouldn't I lie about the results of plagiarism-checking too?

If I saw this as a reviewer, I would think it reflected an odd but almost certainly irrelevant thing about the authors, and then proceed to ignore it.

  • This is also what I was thinking. Perhaps the author has been accused of plagiarism in the past.
    – user44610
    Commented Nov 18, 2015 at 18:15
  • 1
    And if I was an editor, my first inclination would be "Yeah, I'll be the judge of that, not you..."
    – Fomite
    Commented Nov 18, 2015 at 23:33
  • 2
    (+1). It reminds me of Pilger's law: "If it's been officially denied, then it's probably true".
    – Coder
    Commented Jul 2, 2017 at 9:55
  • "The lady doth protest too much..."
    – Fomite
    Commented Jul 3, 2017 at 4:06

There are two separate questions here.

  1. Do authors normally check their own papers for plagiarism? Don't know, but I would assume that it is not that uncommon, especially if they want to preserve their reputation when working with new people who do they not know well.
  2. Do authors put these things into the cover letters? Absolutely not, this sounds pretty insane and one wonders what was the motivation behind it. Perhaps this was the work of a fresh PhD student, who was required to use Turnitin by his supervisor, just to make sure that he did not plagiarize anything. But I would assume that supervisor would order him to remove such sentence from the cover letter ASAP.
  • For 2, one possibility is that the author is worried that if the editor/referee does a plagiarism check, the fact that it's already been submitted to a plagiarism checker might cause a false positive, especially if edits have been made in between. (I don't know whether such a fear is founded.) Commented May 29 at 10:08

One obvious answer is "I know I didn't plagiarize, so why would I check?"

But the obvious answer is not always right. You may well know that you didn't plagiarize deliberately, but there have been cases of people plagiarizing accidentally. A few of these have been in fairly popular books and have gotten publicity. Surely there are many others that did not get in the news.

Our memories are fallible. They are much more fallible than many of us might think. It's not that hard to read something, remember it, but, over time, "assign" it to our own thoughts and forget where we read it.

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