This came up in the comments on Controlling magic through words - possible?, in which the author of the question did not want to detail background elements for fear that others might copy the idea. Based on that, a discussion insured as to whether or not utilizing the ideas presented in a question (or, in a broader context, answers) would make the work using the material derivative.

While not a lawyer, I do have a very strong (unflattering) opinion of copyright law, which has led me to take an interest in it. My understanding is that to constitute a derivative work, direct references would need to be made: either content would need carried over (characters, setting, etc.) or actual portions of the text would need copied (including translations). Indeed, only the second is entirely clear-cut, with situations like LOTR’s elves and dwarves being prominent staples of fantasy. Merely taking an idea and using it without direct use or reference to the source would not constitute derivation.

The only case in which (again, by my understanding) the Worldbuilding license would apply is direct reproduction of material: say, a Q&A book on common writing problems.

While this is perhaps a broad question for meta, I think it is important: if members here believe they can (and possibly intend to) take legal action if their answers are utilized, that needs to be made very clear to all involved, regardless of what the answer to this question is. I very much doubt the majority of people asking questions here intend to place their works under by-sa.

I think someone with direct legal background or perhaps a member of the StackExchange staff would give the most valuable response to this question.

Note that this is not the same question as Using content from answers?, which seems to refer to direct copying of material (as with my Q&A book example above).


2 Answers 2


I'm fairly sure any official answer will just say "read the license, that tells you what you can do." Any attempt to "explain" the license, particularly from anyone official, just dilutes the license as people can try to point to the explanation as well.

The Open Source style licenses are generally written to be clear and non-confusing. It should be possible for anyone to read them and understand what they can and cannot do.

Having said that everything posted to Stack Exchange is licensed under CC-BY-SA as part of the agreement you signed up to when joining the site. That means that this summary page applies:


The question as to whether an idea from a question is copyright is not addressed there however...

  1. I am not a lawyer.
  2. It is generally true that you cannot copyright an idea. That is what Patents are for.

If in doubt talk to a lawyer.

This discussion is also relevant: Re-using ideas or small pieces of code from stackoverflow.com


Ideas cannot be copyrighted. Content can. Stack Exchange licenses under CC-BY-SA the content that users post to the site.

This means, in theory, that anyone using content or derived content has to attribute and link.

Derived content is, I think, the contested point here. My pseudo-legal1 view is that

  • work using the concepts expressed in content in an answer does constitute a derivative work;
  • it would be hard to use the ideas expressed without retaining some semblance of similarity to the original post, which can be used in a legal claim.

Moreover, the license has been put in by Stack Exchange to protect users' content - and they have a legal team who I don't doubt considered it pretty carefully.

tl;dr - your content is protected.

1 I live with two lawyers. That still doesn't mean this is full legal advice. Also, I live in the UK and I do not know US court process (but license interpretation should be the same).

  • $\begingroup$ "Stack Exchange copyrights the content that users post to the site, using the CC-BY-SA license." This is wrong, and it renders your answer wrong. The user posting to Stack Exchange fully owns the copyright to their contributions, which are licensed to Stack Exchange under the CC-BY-SA license, which in turn allows sublicensing under the same terms (so Stack Exchange is allowed to further license, under CC-BY-SA, what you post to others who visit the network). §3 of the terms. You the original creator of the content retain the right to license to others, under CC-BY-SA or any other license. $\endgroup$
    – user
    Commented Jun 6, 2015 at 20:54
  • $\begingroup$ @MichaelKjörling - a product of ambiguous phrasing. I mean what you say. Stack Exchange applies a "sub-copyright" to the user's content when it is posted, through the license; the user still owns it. $\endgroup$
    – ArtOfCode
    Commented Jun 6, 2015 at 21:24
  • $\begingroup$ I think there might be some differences in locality cropping up between my understanding / Tim B's answer (both US) and the UK. $\endgroup$
    – user5083
    Commented Jun 6, 2015 at 21:43
  • 1
    $\begingroup$ @WilliamKappler I'm UK. The UK and US are not very far apart on this. $\endgroup$
    – Tim B
    Commented Jun 9, 2015 at 19:32
  • $\begingroup$ @TimB Sorry, I thought you mentioned the US in your post, but I seem to have been mistaken. $\endgroup$
    – user5083
    Commented Jun 9, 2015 at 20:09

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