In my understanding, the CC BY-SA 4.0 license allows me to redistribute any material posted in Stack Exchange, as long as I put a link back to the original post. Does that mean a user has a right to not allow redistribution of their own posts?

If yes, does that conflict? Do I have to ask them for permission? What if they don't answer?

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    OP grants the license when they share their work. The redistribution has requirements like giving appropriate attribution. But there is no mention of having to ask for permission. The link you show even says: "The licensor cannot revoke these freedoms as long as you follow the license terms." – VLAZ Nov 20 '20 at 8:44
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    Users do not have that right. Nothing in the CC BY-SA 4.0 license grants them that right, nor do the terms of service grant them such rights. – Martijn Pieters Nov 20 '20 at 8:56
  • @VLAZ can the user ask me to not following the license requirement (i.e. allow me to redistribute the content but not attribute the author)? – Ooker Nov 20 '20 at 9:21
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    @Ooker a user should accept the terms of the license in order to post their content. Once they've accepted the terms they can't impose additional requirements."No additional restrictions — You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits." - from the link again. If a user does not want the CC BY-SA license, they should not post their work. – VLAZ Nov 20 '20 at 9:43
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    The user can grant you additional rights at their own discretion, such as allowing you to redistribute the content without attribution. They cannot prevent you from distributing the content under the original CC BY-SA 4.0 license, but under the terms of that license, they may request that you remove their attribution (while still distributing the content under the same license). – Emil Jeřábek Nov 20 '20 at 9:43
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    @Ooker yes that is a possibility. Some users declare such thing in their profile. – Luuklag Nov 20 '20 at 10:04
  • @EmilJeřábek You say: (1) they cannot prevent me from distributing the content under the original CC BY-SA 4.0 license, and (2) they may request me to remove their attribution (while still distributing the content under the same license). I feel like these two contradict each other? Isn't that "prevent" = "request"? – Ooker Nov 20 '20 at 11:25
  • There is no contradiction. Once again: they cannot prevent you from distributing the post under the CC BY-SA 4.0 license, but that license itself happens to give the author the right to request the removal of attribution. If they exercise this right, you can still distribute the post under the license (they cannot prevent that), but you cannot indicate who created it while doing so. – Emil Jeřábek Nov 20 '20 at 11:37
  • @EmilJeřábek If so, then do I need to explicitly say that the user asks me to do this in the distribution? Because the license asks me to attribute. Also, do they have the right to request the removal of attribution anyway? Because probably it's Stack Exchange the company who actually has that right? And my attribution should technically be the post link (property of Stack Exchange), not the author? – Ooker Nov 20 '20 at 14:13
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    No, the author has the copyright to the content. Stack Exchange is only a distributor of the content (under the CC BY-SA license). As for what are the exact legal requirements when redistributing content whose author requested removal of attribution, I don’t know that off-hand, see the text of the license for yourself. Also, see meta.stackexchange.com/q/96732 for how SE itself handles removal of attribution requested by post authors. – Emil Jeřábek Nov 20 '20 at 14:30
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    Note that the attribution requirements under the CC BY-SA licenses are substantially more than "put a link back to the original post". While you will need to make a determination of the requirements on your own, or have a lawyer do so for you, how I, personally, distill the requirements down (for CC BY-SA 3.0) is detailed in this answer on Meta Stack Overflow. – Makyen Nov 21 '20 at 2:05
  • I wonder why this question is downvoted. Any explanation? – Ooker Nov 21 '20 at 6:16
  • Author attribution is also required (I think). – P.Mort. - forgot Clay Shirky_q Nov 22 '20 at 18:05


To quote the page you linked describing the license:

The licensor cannot revoke these freedoms as long as you follow the license terms.

Because posting on the Stack Exchange network grants such an irrevocable license to the content (see "Subscriber content" here), a user is unable to forbid redistribution of material they posted on the Stack Exchange network, as long as the person doing the redistribution follows the license (including, for instance, a link back to the post).

You are not required to ask, because the license has already been granted. Even if they ask you not to redistribute it, you still can, because the license cannot be revoked.

One exception: if the user did not have the right to license the material to Stack Exchange in the first place (for example, it was copied from somewhere else), then there was never a valid license in the first place, and the actual copyright holder could enforce their rights. The user should never have posted this material on Stack Exchange in the first place, but occasionally people break the rules.

  • Who owns the content? Stack Exchange or the user? Would ownership be the same with authorship? – Ooker Nov 20 '20 at 11:28
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    @Ooker the authorship is not really determined. The OP might not be sharing something they've made. Indeed, it's often that people copy an example from a book to ask for explanation. They aren't the authors in that case. The ownership of the content belongs to the user. As in, the whole of the post itself, for example "I don't understand X in <code> - even if the code is from a tutorial, the user owns the content of the entire post. However, the user also grants a license to the site under the terms of CC BY-SA 4 thus allowing the re-sharing and modification of this content. Among other – VLAZ Nov 20 '20 at 12:52
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    @Ooker things, this allows the sites to function. Without re-sharing it's not possible to show a question to potential answerers. Without modification, it's not possible to edit a question or to post an answer that's a transformation of the content of the question (into something that works). Without re-sharing again, it's not possible for others to use the solutions. The problems in this chain is if the original poster wasn't allowed to re-license the work they are asking about. If the user wishes to impose additional restrictions after posting that's in breach of CC BY-SA 4 – VLAZ Nov 20 '20 at 12:52

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