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I’ve seen some similar questions, but was wondering about a more specific case. I wrote a Stack Exchange answer, and would like to use it in one section of a book I’m writing (which will be commercially sold). I also modified the answer, and added to it, but some original passages remain. I’m wondering if, as the author, and with proper attribution that the section is based on my Stack Exchange answer, with a link, this is legally acceptable?

feetwet
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Skeptic
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3 Answers3

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Yes, that’s allowed. Under the Stack Exchange terms of service, content you upload is licensed to Stack Exchange Inc. on a non-exclusive basis under CC-BY-SA 4.0. The terms of service do not give Stack Exchange the copyright to your contributions, and a non-exclusive license means you are not promising Stack Exchange that “only Stack Exchange will be allowed to use this content.” That means you can continue to do whatever you want with your own content and do not need to mention Stack Exchange at all. The only restriction is that you can’t stop Stack Exchange from continuing to use your Stack Exchange content under CC-BY-SA 4.0, and since it’s a Creative Commons license you also can’t stop anyone else from using your Stack Exchange content under that license.

cpast
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    Thank you very much. I’m curious about the “Share Alike” clause. Will this mean that the portion of the text in my book may in general be used onward? I suppose the “attribution” clause means it has to be cited, so in that sense it wouldn’t necessarily differ from quoting any other part of the book. – Skeptic May 15 '22 at 17:08
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    @Skeptic The ":share alike" provision means that if someone else uses the answer(or a work derived from the answer), that person must release it under the same or a compatible license. But the copyright holder (normally the author) of the answer is not bound by the license, and may use the answer in any way that s/he pleases, and need not keep it under anyy CC license. – David Siegel May 15 '22 at 19:41
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    @Skeptic A bookl incorporating part of an answer would be a separate work, under a possibly different license (probably "all rights reserved"). No one would have any different rights to the part derived from the answer than to any other part of the book. However anyone could use the original, unmodified answer, from the original SE post.. But not any rights to any modifications released only with the book. – David Siegel May 15 '22 at 19:45
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    Crucially, you have not given StackExchange the copyright. It's your work, but you're allowing them to show it under a particular license, in the same way that you don't give GitHub the copyright to code you upload to it, merely permission to display the code on their website (assuming your repo is public, of course). So you can still do whatever you wish to the answer you wrote, since it does belong to you. – Silvio Mayolo May 16 '22 at 00:49
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    It may be worth noting in the answer that one ramification of not being able to stop SE from continuing to use the content is that you can’t give anyone else an exclusive license. I don’t know the publishing industry that well, but it wouldn’t shock me if publishers generally expect the contents of things they publish to be exclusively theirs to publish. That couldn’t be the case for an SE answer (though of course an SE answer does not constitute a full book in the first place, and presumably the rest of the book would be exclusive). – KRyan May 16 '22 at 01:12
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    You can always modify your answer just enough to make it a derived work. If you put this derived work into your book, then nobody has the right to copy it from your book, but they can copy the original on stack exchange. – gnasher729 May 16 '22 at 10:53
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    @KRyan enough non-fiction books will deal with quotes that aren't available under exclusive licenses. so they should be able to handle excerpts that aren't under exclusive license – ratchet freak May 16 '22 at 13:08
  • It's also possible that the portion of the book corresponding to the answer would be small enough that copying it would be deemed "fair use". But there's no objective criteria for this, it has to be decided on a case-by-case basis. – Barmar May 16 '22 at 13:54
  • @Barmar Fair use works the other way: the portion of the answer that is copied would have to be small. – wizzwizz4 May 16 '22 at 14:14
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    @wizzwizz4 I was thinking in terms of the book publisher expecting to have exclusive copyright to the book's contents. Even if they do, this one portion might be small enough that copying it would be fair use. – Barmar May 16 '22 at 14:33
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    @KRyan book authors do not normally transfer the copyright to the publisher. – phoog May 16 '22 at 16:00
  • @phoog Wasn’t suggesting that they do, only that they typically (I assume) give a publisher an exclusive license to the bulk of the work. Quotations—including self-quotations published elsewhere like this, I guess—would be an exception. But if they’re not getting an exclusive license to something of value, why should they bother publishing (and publicizing) it? – KRyan May 16 '22 at 16:05
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    @KRyan: I would tend to expect that the rest of the book (which would be exclusive) would be of sufficient value that the publisher would simply write in an exceptional clause for the non-exclusive content (i.e. "this one bit is non-exclusive, but everything else is exclusive"). If that is not the case, then perhaps you shouldn't be getting a book deal in the first place. – Kevin May 16 '22 at 18:58
  • @Kevin Yes, I’ve acknowledged that several times. In the context of an entire book, vs. a single Stack answer, this is almost-certainly a non-issue. But the same legal situation (content you have copyright to but to which you have given someone an indefinite license to use not being eligible for an exclusive license to someone else) could be more significant in other contexts. – KRyan May 16 '22 at 19:25
  • Of course, the improvements others contributed to your answer aren't your property, which might make relicensing your answer a bit more problematic. – Deduplicator May 16 '22 at 20:35
  • By the same token, you would also be allowed to quote anyone's Stack Exchange comments / questions, along with attribution and a link to the license (as per https://creativecommons.org/licenses/by-sa/4.0/) – bittahProfessional May 17 '22 at 15:25
  • @gnasher729 Under US law, that would be considered copyright misuse. To the extent that someone could show that it was more likely than not that you had done that, you could not enforce your copyright. You absolutely cannot deliberately make it difficult for people to determine what content you have and have not given them rights to and then complain when they get it wrong due to the confusion that you deliberately created specificaly to make that hard. – David Schwartz May 17 '22 at 20:58
  • David, one version of the answer is on a stackexchange site, the other is in a book. There is no reason for you to assume that you can copy things you found in a book. And it is clear that you can copy the version on stackexchange. It’s very clear which version they can copy. – gnasher729 May 20 '22 at 07:51
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I also modified the answer, and added to it, but some original passages remain.

If the content is strictly your own plain text and equations that's one thing, but some posts may also contain block quotes from other sources and/or images, and their status will have to be examined separately and individually beyond SE's CC-BY-SA.

uhoh
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I believe there is another issue you may have to consider, and that's your contract with the book publisher. You have already granted some rights to Stack Exchange, and that means you cannot assign all rights to the publisher, which they may by default want you to do.

The thing is, this is between you and the publisher and they will probably be okay if they don't have exclusive rights to a few paragraphs of the book. I am just making the point that the publisher also does have a stake in what you have done with the material before.

I am very much not a lawyer but this might be something to ask more knowledgeable people about.

Mark Foskey
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