Effective today, all Subscriber Content on Stack Overflow and the Stack Exchange network will be available under the terms of version 4.0 of the Creative Commons Attribution-ShareAlike (CC BY-SA) license.

This change follows our last Terms Of Service (ToS) update where we inadvertently introduced a point of confusion: the new ToS links to version 4.0 of the CC BY-SA license in support of defining the use of a Creative Commons license, where the previous terms linked to version 3.0 of the license. That’s not a problem itself, but the footer section of our websites continued to specify version 3.0 of the CC BY-SA license; this was an oversight.

It was our intention to update the footer information in a manner that was commensurate with the updated terms. We'd like to thank those from our communities that thoughtfully pointed out the issue and we have subsequently improved our review process.

Today's change will bring things into alignment by updating the information in the footer and we will continue forward under version 4.0 of the CC BY-SA license. This change encompasses all Subscriber Content as described in our ToS including data dumps as well as any content previously made available by Stack Exchange under the terms of version 3.0 of the CC BY-SA license.

If you have any questions about how licenses may or may not impact your business or personal projects, it's better to speak with your own attorney — we can't provide advice specific enough to be of much use in most cases.

4.0 has many advantages, and we encourage you to read the announcement letting the world know it was ready as a starting point if you're curious about the improvements.

We're happy to hear any thoughts about this, particularly from those in our international communities. If you've got questions pertaining to the change, we'll do our best to answer them, as long as we can answer without giving specific advice.

Update: Please read our update on Creative Commons Licensing for more follow up on issues that stemmed from the change in license described above.

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    For those curious, see what's new in 4.0 here. – TylerH Sep 5 '19 at 15:04
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    Just a curious question, why is the whole footer lowercase except your company name? I'd like to see CC BY-SA properly capitalized as it's some kind of abbreviation? – iBug says Reinstate Monica Sep 5 '19 at 15:17
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    The Stack Overflow ToS can be interpreted to read that SO receives a CC-BY-SA license from users and additional rights. This relicensing is not possible under the CC license and can only happen if SO has additional rights. Is this confirmation that SO does not consider itself bound by the CC license? Or alternatively, does SO assume to have received a license under all CC-BY-SA versions so that it can choose which version it passes on to the public? I'd just be interested to hear an argument why you've been allowed to do what you've already done. – amon Sep 6 '19 at 8:01
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    I don't know if version 4 is really better than version 3 and I wonder if there really was a need for change, but what I really miss is this running ideas concerning the user generated content through the community before. I mean, what if users didn't like CC-BY-SA-4.0 It's more like announcements. Not sure if it ever was different, but somehow it feels like it. Anyway, doesn't really matter. – Trilarion Sep 6 '19 at 17:38
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    Tim, has this retroactive change been run by the legal department? I'm no lawyer, but I highly doubt you have the ability to change the license of content that doesn't belong to you. When I have posted answers, I gave you a nonexclusive license under CC BY-SA 3.0. I am the only one who can change that. – jhpratt Sep 6 '19 at 23:43
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    @jhpratt, I strongly recommend you read the terms of service: the rights you grant to Stack Exchange are considerably broader than a simple CC-BY-SA. – Mark Sep 9 '19 at 19:50
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    @Mark I have read the "subscriber content" section, which is the relevant part here. It's pretty clear that Stack Exchange has the right to use it pursuant pursuant to Creative Commons licensing terms (CC-BY-SA). This post makes clear that that was CC-BY-SA 3.0. Apart from reiterating the commercial side of things, I see nothing else that specifies that Stack may relicense content whose copyright I retain. Perhaps you could point me to something I'm missing? If you're looking at the opening section, that's Stack's content, not user-submitted. – jhpratt Sep 9 '19 at 21:35
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    @DarrenCook Code in questions and answers never was covered by an MIT licence. The MIT licencing plan that you linked to was postponed indefinitely, as you can see for yourself if you click through. – Emil Jeřábek Sep 10 '19 at 8:44
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    It's been almost two weeks. Will there be any followup to this at all? Zero staff engagement since these concerns about our content were raised, unless there's been another post that I've missed. Footer still says 4.0. – Lightness Races in Orbit Sep 15 '19 at 17:30
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    The silence on the part of SE is troubling. Several people have raised the fact that this change does not comply with the Creative Commons guidelines for upgrading to 4.0 from previous versions of the licenses, yet there has been no response. To me, the biggest concern is that SE is misrepresenting the license under which content that I have previously provided is available. The second biggest concern is that this demonstrates a lack of a grasp on legal matters and licensing agreements with contributors. Both are serious concerns. – Thomas Owens Sep 17 '19 at 0:16
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    What implications might this have for those who have used content under the provisions of 3.0, not just for the submitters? Granted the real-world changes might be minimal, and may in fact me more lenient, but a retroactive application of a license change could have unintended consequences in that regard too. – Dan Sep 19 '19 at 10:41
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    Just for reference, my request for an update on the legal status of this change currently has the same score (+29) as this. It's also far less controversial, with an upvote:downvote ratio of 10.7 versus 1.3 for this. If that isn't telling, I'm not sure what is. – jhpratt Sep 25 '19 at 0:02
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    Happy three weekiversary everyone! – Lightness Races in Orbit Sep 26 '19 at 10:36
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    In case you don't have answers sorted newest first, Tim Post's answer on this question is here. – I say Reinstate Monica Sep 29 '19 at 1:32

24 Answers 24


I like CC BY-SA 4.0. IMO, it's better than 3.0. I'd prefer to use it. I've chosen to use 4.0, instead of 3.0, on projects of my own. However, my preference doesn't affect the current situation with respect to existing content on Stack Exchange.

Stack Exchange doesn't have the right to unilaterally change the license of previously submitted content.

Beyond what might exist in the CC BY-SA 3.0 license, I've seen nothing that indicates Stack Exchange has the right to change the license for previously submitted content. No version of the TOS which I've read grants the additional right to Stack Exchange to re-license prior existing content, or, in the future, to re-license content submitted under the current TOS.

If you believe such a right was granted outside of the CC BY-SA licenses, I would appreciate knowing what wording in which document you feel grants that right.

Migrating from CC BY-SA 3.0 to CC BY-SA 4.0

The primary issue is migrating from CC BY-SA 3.0 to CC BY-SA 4.0. Unfortunately, Stack Exchange unilaterally shifting the existing license on older subscriber content from 3.0 to 4.0 isn't permitted, or at least that's the opinion of the Creative Commons, who wrote the licenses.

Creative Commons has a 4.0 upgrade guidelines document, which says in part (emphasis mine):

Upgrading from prior versions to 4.0

Existing content:

  • Who owns the rights?
    • ...
    • If the contributors, then need permission to relicense. Without permission (via terms of use or otherwise), then that content remains under prior version.

Adaptations of existing content:

  • Who owns the rights to the original?
    • ...
    • If the contributor, then can license new contributions to an adaptation under 4.0 but original contributions remain under prior version unless express permission to upgrade is obtained.

You can change what happens with respect to old contributions moving forward by mutual agreement with the user that submitted the content (i.e. each question, answer, comment, tag excerpt/wiki, and edit). In other words, you can get permission from each author to re-license the content they submitted, but you can not do so unilaterally.1 You could change the TOS such that new use of the site relicenses old contributions by that user, but that's something you should discuss with your lawyers.

However, as a practical matter, you will never be able to get permission from every contributor to switch to the new license for all previously submitted content (e.g. users who never return to the site), which means you must deal with mixed licenses in some manner.

Was this change planned and intentional?

This announcement says that you "inadvertently introduced a point of confusion". This can be read many different ways. One is "the person who was updating the TOS mistakenly typed a 4 instead of a 3 when linking to the CC BY-SA license." The wording you've used makes it sound like the change was a mistake that you just decided to go with. It doesn't sound like you put planning into making such a change.

The fact that the change from linking/saying CC BY-SA 3.0 to CC BY-SA 4.0 did not happen close to seamlessly in all places on the site (or at least most) argues that this was not a planned change. In particular, that CC BY-SA 4.0 has been linked in the TOS for more than a year and you are only getting to making an announcement and other on-site changes now, really makes it look like the change was, at least initially, just a mistake.

Please, run this by your lawyers.

If this was not planned and/or you have not yet run this by your lawyers, I strongly recommend that you inform your lawyers of the current situation and ask for their advice.

My belief is that by making this change you've created a quite complex situation, which is difficult to resolve. My understanding is that the resolution recommended by the Creative Commons requires changes to how you display subscriber content (i.e. indicating the applicable license individually for each question, answer, comment, tag excerpt/wiki, and edit).

You might be able to get away with just making it clear as to the date that the license changed, but doing that will require every user who copies content from Stack Exchange to individually determine which license is being used for each portion they copy.

I am not a lawyer. This is not legal advice. This is just my interpretation from reading the license, the current TOS, my memory of the old TOS, etc. I strongly recommend that you seek the advice of your lawyers.

  1. You can change your TOS unilaterally, but that doesn't change what agreements are in place from the past. Changing those existing agreements (i.e. the existing licenses) requires action on the part of the other party (i.e. your users).
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    Comments are not for extended discussion; this conversation about legal issues has been moved to chat. – Monica Cellio Sep 8 '19 at 3:44
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    @FedericoPoloni volume, no sign that the discussion was winding down, and flags. Chat works much better for the kind of back-and-forth that people were having; there's at least rudimentary threading in chat, unlike comments, and even though meta is fundamentally about discussions, there are still practical limits. There might be other threads that should be moved too, but flags drew me to this one. – Monica Cellio Sep 8 '19 at 21:19
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    I have written to the real lawyers (legal stackoverflow com, at least I hope there will be real lawyers) about this issue some days ago. As soon as I get an answer, I will post it here. I also included my explicit disagreement with the attempted re-licensing, just in case that makes a difference. – Trilarion Sep 9 '19 at 13:58
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    @called2voyage Silence so far. If I don't hear anything by Friday I'll send a second inquiry. All I can do. Feel free to also send them a message of your own. Whoever gets a reply first can post it. – Trilarion Sep 11 '19 at 7:53
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    I'd like to point out that they also changed Area 51 to CC BY-SA 4.0 from 2.5. – Peilonrayz Sep 11 '19 at 21:25
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    @trlkly That answer has previously been mentioned/linked in an earlier comment (see comments moved to chat). As my answer here says, the Creative Commons, the people who wrote and published the licenses, very explicitly disagree with what the answer you have pointed to says (as I've quoted in bold in this answer). In addition, and importantly, what Stack Exchange provides is a Collection, which is explicitly barred from being an Adaptation (stated twice in the license). Thus, the section of the license which that answer is relying on, 4(b), can not apply (it applies only to Adaptations). – Makyen Sep 16 '19 at 5:57
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    @Zaibis Thanks. I will do that. However, currently there is no danger. I don't need a permission of anyone to publish an empty string. :) – Trilarion Sep 18 '19 at 8:24
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    Didn't get any response (wrote three times to legal stackoverflow com). Now wrote also to the FSF. Nothing more I can do. (meta.stackexchange.com/a/333745/260073) – Trilarion Sep 24 '19 at 11:53
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    "You can change what happens with respect to old contributions moving forward by mutual agreement with the user that submitted the content." Please heavens don't have this turn into, "Your continued use of this site indicates your agreement with this and any future change in licensing." I miss Joel. – ruffin Sep 25 '19 at 2:06
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    @Kruug not true at all. According to the ToS, SO is granted a perpetual license to use the content; that does not automatically give them the right to relicense it, only "access, use, process, copy, distribute, export, display and to commercially exploit" it. – KutuluMike Sep 25 '19 at 23:44
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    So... time to test out the arbitrator that SO had us all waive our class action rights in favour of? – mbrig Sep 26 '19 at 15:53
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    @JeffAtwood Since, unlike the current powers that be, you seem to be actually interested in communication, would you care to brielfy explain what did you consider back then to be the legal basis for unilateral relicencing of the content from 2.5 to 3.0? – Emil Jeřábek Sep 30 '19 at 8:25
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    @JeffAtwood We didn't "forget"; OrangeDog pointed this out three weeks ago, like two pages down from your comment. We let it pass at the time, but we shouldn't have. Certainly, "we did this before" is not a justification to do it again! And "get some context, folks!" isn't a constructive way to engage with people who are so rightfully upset. – Lightness Races in Orbit Sep 30 '19 at 10:43
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    @JeffAtwood You avoided the part in the license where it says unilateral, retroactive applications of licenses are not allowed. Get some context. Perhaps it's necessary for the users of the site to start a lawsuit against Stack Exchange in order to remedy everything. – The Anathema Oct 20 '19 at 5:11
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    @JeffAtwood what do you mean? "Did you forget we broke the law back then so we can do it again? Get some context." – Prof. Falken Nov 4 '19 at 15:23

I have some serious concerns with this, especially after the last round of licensing fiascos around the MIT license.

I want to be clear: I like the Creative Commons licenses for text. I think that CC-BY-SA is appropriate for content contributed to Stack Exchange. I think that CC-BY-SA 4.0 is a fantastic license and I use it myself.

However, you have not obtained my permission to change the license of the content that I have contributed. The Terms of Service did not require me to grant that permission as part of using the service (and even if you added it, you would need to handle the case where someone decides to stop using the service but does not grant permission for existing content) and I have not received a request for permission to update the license of my content.

My biggest concern here, like it was in the last rounds of licensing discussions, is a fundamental misunderstanding of the rules and laws around licensing. This does not give me confidence.

I'd like to make my concerns more explicit.

Before September 5, the Stack Exchange Network Terms of Service was an agreement between the users (myself) and SE that I agreed to by using the service.

One of the agreements in the pre-September 5th TOS was an agreement that I license "and and all content" that I provide to the public Network be "perpetually and irrevocably licensed to Stack Overflow on a worldwide, royalty-free, non-exclusive basis pursuant to Creative Commons licensing terms". Per the TOS, this is a "perpetual and irrevocable right and license to access, use, process, copy, distribute, export, display and to commercially exploit such Subscriber Content".

I would point out that I do not grant anyone the right to change the license of my contributions without permission in the Terms of Service, so we must consult the Creative Commons licensing terms that I am granting.

The Creative Commons licensing terms linked to was CC-BY-SA 3.0. The original answer here makes it clear that at some date, CC-BY-SA 3.0 was linked to. During an update, the wrong version (4.0) was linked to. This appears to be unintentional and wasn't communicated in change notes to users to give adequate information to make an informed decision on accepting the new Terms of Service.

For the sake of argument, we can say that this change to the ToS is fine - SE can arbitrarily require new contributions to be licensed under whatever they ask. It is up to the users to understand that. The issue is with past contributions.

To be clear on definitions, an individual contribution to a site on the SE network is a Work (see 1.h). A set of questions, answers, and comments that is made available is a Collection (see 1.b). I'd point out that SE content is not an Adaptation (1.a).

When I submit a post to an SE site, I granted SE a perpetual and irrevocable right and license to that post under CC-BY-SA 3.0. They then use this license to make my post available to others but also to form a Collection with other posts also submitted under CC-BY-SA 3.0. Prior to September 5, both the individual Works by various people plus the Collection were CC-BY-SA 3.0.

4.a in CC-BY-SA 3.0 states that "You may Distribute or Publicly Perform the Work only under the terms of this License". In this case, "You" is someone who received the Work under the license. This is a prohibition on relicensing Works. This section also addresses Collections - "This Section 4(a) applies to the Work as incorporated in a Collection, but this does not require the Collection apart from the Work itself to be made subject to the terms of this License."

4.c in CC-BY-SA addresses distribution of the Work in a Collection. It requires that all copyright notices remain intact. Prior to September 5, the Collections were also distributed under CC-BY-SA 3.0.

8.a makes this even more clear: "Each time You Distribute or Publicly Perform the Work or a Collection, the Licensor offers to the recipient a license to the Work on the same terms and conditions as the license granted to You under this License." Again, "You" refers to SE distributing individuals Works in a Collection.

The new Terms of Service require new contributions to be licensed under CC-BY-SA 4.0. This is OK and acceptable - totally fine for SE to do at any point in time. However, due to the fact that permission to relicense was not granted, the license of existing works cannot be unilaterally changed.

CC provides upgrade guidelines for applying 4.0. For existing content, contributors own the rights and granted SE a license. The guidelines say that the publisher will need permission to relicense. Without permissions (which can be granted via terms of use), the content remains under the prior version and there are guidelines for dealing with mixed-version content. The guidelines for adaptations do not apply since SE is not an adaptation, but a collection.

Given that the ToS did not grant permission to relicense works and CC-BY-SA 3.0 explicitly prohibits relicensing works and the CC guidelines for migrating Works were not followed, I'd like an actual answer from SE identifying (with quotes) exactly what sections of the Terms of Service or CC-BY-SA 3.0 are believed to grant them the rights to relicense my contributions.

I'd note that I am not objecting to the collection of works being licensed under CC-BY-SA 4.0. I'm also not objecting to new content being licensed to SE under 4.0.

I simply want SE to demonstrate a basic understanding of copyright and licensing - right now, I'm very quickly losing trust in SE to appropriately handle my contributions.

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    MIT License fiasco? Can you link me? – George Stocker Sep 6 '19 at 14:36
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    @GeorgeStocker Googling the term 'Stack Overflow MIT license' gave me this as the top result: meta.stackexchange.com/questions/271080/… – TylerH Sep 6 '19 at 14:44
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    @TylerH Yeah, that's it. The linked post that is lower than -300 is kind of what I was thinking of. – Thomas Owens Sep 6 '19 at 14:46
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    So much this. I had a real deja vu moment when I saw this post. Everything I can find says they can't just change the license on existing works, yet that appears to be what they are trying to do. – NathanOliver Sep 6 '19 at 14:50
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    @TylerH Even that at least said all new code contributions. That little three-letter word "new" makes an awful lot of difference here. – user Sep 7 '19 at 10:48
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    @hakre See the Creative Common's guidelines for upgrading to 4.0, specifically the section on updating existing content from prior versions. Per the Terms of Service, I continue to own my content but granted SE a CC-BY-SA 3.0 license to it. In order to upgrade, they must get my permission. Terms of use is acceptable, but I need to explicitly accept those terms of use. The prior terms of use did not grant them the right to upgrade the license from 3.0 to 4.0. CC says that what SE has done is not allowed. – Thomas Owens Sep 17 '19 at 0:08
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    @hakre Stack Exchange is a not an Adaptation. That does not apply. A question on Stack Exchange is a collection that includes the content of the question, the content of all of the answers, and the content of all of the comments on either. Each part (question, answer, comment) is also an independent work that is licensed to Stack Exchange individually by its creator. – Thomas Owens Sep 17 '19 at 14:20
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    @hakre No, it does not because 4.b only apples to adaptations and SE content is not an adaption. If SE made an adaptation of something I licensed to them, then they could release that adaptation under a license that meets the criteria defined in 4.b (which would be CC-BY-SA 4.0). However, since it's not an adaptation, they need my permission to share my work under a modified license. 4.a and 4.c apply where 4.a applies to my specific contribution and 4.c applies to the collection that contains my contribution along with other contributions and neither of those permit changing the license terms – Thomas Owens Sep 17 '19 at 14:53
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    @hakre This is not about an incompatibility. As a content creator, prior to September 5th, I granted SE a CC-BY-SA 3.0 license to use my work. Under 4.a and 4.c of CC-BY-SA 3.0, they cannot change the license of my contributions - my individual questions, answers, and comments remain CC-BY-SA 3.0. However, on September 5, the documented license changed. They can require a CC-BY-SA 4.0 license for new contributions, but do not have the right to distribute previous contributions to others under anything other than CC-BY-SA 3.0. – Thomas Owens Sep 17 '19 at 16:48
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    Just FYI: The TOS actually linked to CC BY-SA 4.0 at least as far back as 2018-05-02, but was CC BY-SA 3.0 on 2018-04-28. However, that's just a detail as to when the license granted by contributors for new content changed from a 3.0 license to a 4.0 license. Ironically, it brings up an additional issue of the year+ where SE was distributing content actually licensed under 4.0 as being licensed under 3.0. – Makyen Sep 28 '19 at 21:01
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    @JeffAtwood Just because it was done in the past doesn't make it right or legal. Also, I didn't have the knowledge that I do now of copyright and open source licensing in 2009 to raise objections, or I would have done so then as well. The fact that this has been done in the past only makes it even more confusing since there may be multiple undocumented licenses for content out there and people don't know what license it is available under. – Thomas Owens Sep 30 '19 at 0:31
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    @JeffAtwood I'd agree that each version is supposed to be better. However, the license terms are pretty clear, as are the CC guidelines for upgrading to 4.0 - the author must grant permission, and the TOS does not require me to grant that permission. From my POV, the solution is easy - I just need to be officially asked if I'm OK with letting them license my content CC-BY-SA 4.0. Until then, it's under the license that the TOS at time of submission said it is. – Thomas Owens Sep 30 '19 at 1:28
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    @JeffAtwood You may well feel it's reasonable to make the assumption that a later version of the license "benefits all involved" but appeal to common sense doesn't give you the right to unilaterally make that decision on behalf of the copyright holder. – Ant P Sep 30 '19 at 9:35
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    It's not even difficult to grasp. I mean, this is literally the entire foundation of what a licence is. An agreement between two parties. What's hard to comprehend about that?! – Lightness Races in Orbit Sep 30 '19 at 10:43
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    @TomBlodget Given their thorough misunderstandings and/or disregard of multiple legal topics, I doubt very much that such data would be correct. And, in the first place, I doubt very much they have it. Eg. as the license of a public post shouldn't be secret in any way, why isn't it anywhere in the data dumps they publish? – deviantfan Oct 10 '19 at 4:06

As animuson wanted this phrased as a question:

Are you sure you're legally allowed to relicense all content without asking the copyright holders (i.e. all contributors) individually for permission? If so, by what justification? As detailed in other answers it looks like CC-BY-SA 3.0 doesn't allow it.

The question has been asked before, but never answered definitively.

The previous relicensing plan explicitly did not apply retroactively.

I just saw that in April 2011 you unilaterally changed all content from 2.5 to 3.0 without any legal explanation. I imagine back then almost nobody noticed. It seems this was after a similar accidental change to the terms.

Also asked as a separate question.

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    Hopefully the lawsuits SE will now get won't make it go bankrupt, it's still useful. – Shadow Wizard Wearing Mask V2 Sep 10 '19 at 11:52
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    meh... surely people will find ways around it. – Shadow Wizard Wearing Mask V2 Sep 10 '19 at 11:57
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    @aCVn oh yeah. I think I did that :) – OrangeDog Sep 10 '19 at 12:41
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    @aCVn That's wonderful for those of us that never did because they never provided the secure means that was promised. – jhpratt Sep 10 '19 at 15:20
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    Of course, any former contributors who stopped using Stack Overflow before May 2018 will not have agreed to the new ToS with the binding arbitration clause in any form, nor can they have consented to this license change (unless they somehow did so in advance, e.g. announcing on their user profile that SE is free to relicense their contributions under any CC-By-SA version). There seem to be quite a few such users, even ignoring those who have deleted their accounts. – Ilmari Karonen Sep 11 '19 at 13:25
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    @OrangeDog: EU citizen here, I can just waive that whole "mandatory arbitration". And to counteract all those caps, I HEREBY WAIVE MANDATORY ARBITRATION. – MSalters - reinstate Monica Sep 17 '19 at 13:32
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    Heh, I'd forgotten I'd commented on that 2.5->3.0 post. Ofc that was ignored too – Lightness Races in Orbit Sep 23 '19 at 10:14
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    @rene We have absolutely not "moved on". This is an ongoing dispute that is still very much in progress. Don't let its one-sided nature fool you. – Lightness Races in Orbit Sep 27 '19 at 8:49
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    @LightnessRacesinOrbit: we could write to every single Stack Overflow user via their email address, and ask them to fill in a questionnaire about whether they have "moved on" or not! ;-) – halfer Sep 27 '19 at 23:24
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    Take a look at the stackoverflow site footer in the wayback machine circa Jan 2009. Note the CC version. Note the current CC version. Same process, different year. – Jeff Atwood Sep 30 '19 at 0:29
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    @JeffAtwood indeed, and I’m not sure it was legal then either, nor was it ever justified with reference either to the TOS or license. I mentioned that in my answer. – OrangeDog Sep 30 '19 at 7:43
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    @JeffAtwood so you broke the law before, it's okay now too. – Prof. Falken Dec 11 '19 at 9:48
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    @OrangeDog well, such clausr abou arbitration need not be valid for EU contributors, if I undetstood some previous discussions correctly. – yo' Jan 15 '20 at 8:16

Another subtle way in which the move to 4.0 is problematic is the following: CC-BY-SA 4.0 requires that any change made to the source material must be explicitly marked. And two changes that SE makes automatically to all published content are:

These changes must now be explicitly marked as modifications.

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    Insofar as these count as modifications that need to be marked under CC-By-SA 4.0, there are plenty of others that SE also automatically makes to all posts. Besides the big and obvious one (submitted content is in Markdown, SE converts it to HTML for presentation), there's also code syntax highlighting on SO, MathJax rendering on Math.SE, automatic conversion of YouTube links to embedded iframes on Movies.SE (which is not even currently shown in the edit preview!), etc. All of these may also change at any moment, even if the post is not edited by its author or anyone else. – Ilmari Karonen Sep 6 '19 at 8:37
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    @IlmariKaronen Personally I consider them to be two different categories. What you mention is simply "rendering" the Markdown code in a convenient way; it is an operation that alters form but not content. Changing the target of a hyperlink the content creator has provided is something different. – Federico Poloni Sep 6 '19 at 8:53
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    Certainly some of the changes I listed can be regarded as mere technical modifications needed to convert the content from Markdown to HTML; but then, so can the addition of nofollow attributes, given that the Markdown link syntax provides no way to specify whether a particular link should have the attribute or not. And the YouTube link-to-embed conversion most definitely does change the URLs, even beyond the fact that it turns them from clickable links into iframes. (It basically just extracts the video ID and the start time from the URL, and discards all the rest.) – Ilmari Karonen Sep 6 '19 at 9:18
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    @FedericoPoloni If the HTML is just a presentation of the content then adding nofollow does not change the content, it's just something added to the presentation with no visible difference. – Giacomo Alzetta Sep 6 '19 at 9:20
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    Anyway, I have no particularly strong opinion on whether the changes you mention are desirable (if anything, I rather wish SE wasn't so eager to slap nofollow on all the links) or something that needs to be marked as modifications under CC-By-SA 4.0. I merely wanted to point out that you seem to have cherry-picked two specific controversial parts of the SE Markdown-to-HTML conversion process and ignored all the rest. – Ilmari Karonen Sep 6 '19 at 9:23
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    OK, let's forget about nofollow for a second; how is rewriting affiliate links part of the presentation? There is no visible change in the landing page on Amazon up to now (only to someone's wallet), but nothing guarantees that it will always be the same. It's Amazon's proprietary API, they are changing some HTML get parameters. – Federico Poloni Sep 6 '19 at 9:55
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    It also says "For trivial modifications, such as correcting spelling errors, it may be reasonable to omit the notice." I would consider your examples as more trivial than that, even if they were made to the actual content and not the presentation. – OrangeDog Sep 6 '19 at 16:57
  • 1
    If this is true, is stackoverflow.com/help/referencing now out of date? Is an extra bullet point required? If the content is from the stack exchange network, indicate whether you have modified the original in any way. – dbc Sep 6 '19 at 17:42
  • @dbc No, those guidelines apply to quotations and similar things. Referencing != reproducing. – Federico Poloni Sep 6 '19 at 19:54
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    @FedericoPoloni - I'm specifically thinking of a situation where I copy some code from another question or answer and make some modification. I've been following those rules in such situations: 1) Give a link; 2) Copy only the necessary code; 3) Name + link of the original author. Do I now need to do 4) Explicitly indicate whether & how I modified the code? – dbc Sep 6 '19 at 20:09
  • @dbc No, if I understand correctly you just need to write that you modified the code, not how. – Federico Poloni Sep 6 '19 at 21:21
  • OK that's not hard then. But it sounds as though stackoverflow.com/help/referencing now needs an update. I'll add an answer pointing that out. – dbc Sep 6 '19 at 21:27
  • @FedericoPoloni A quotation is a reproduction. The example given by CC is a quoted excerpt. – OrangeDog Sep 7 '19 at 9:24
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    @OrangeDog There are two different issues here that are often confused: plagiarism, and copyright matters. I can legally use a (short) quote from a book, even if it is copyrighted. But, even if I reproduce a public-domain source, I am still supposed to state explicitly who the author is instead of trying to pass it as my own writing, to avoid plagiarism. Plagiarism is a moral/professional/academic issue, copyright is a legal one. The page stackoverflow.com/help/referencing explains how to avoiding plagiarism, not copyright infringement. – Federico Poloni Sep 18 '19 at 13:49
  • @FedericoPoloni only in some jurisdictions. Regardless, the authors of the license say that a quotation is a reproduction. Further, quoting != referencing. – OrangeDog Sep 18 '19 at 13:53

Right after this announcement here from Tim Post made on Sep 5th, I wrote to the legal department of the Network (legal at stackoverflow dot com) on Sep 7th in the hope of getting a clarification. I wrote a very polite message expressing my explicit disagreement with the re-licensing of existing content, doubting the legality of the re-licensing and asking for an explanation.

For a week, I did not receive a reply, so I wrote a nice reminder again on Sep 16th. I carefully checked my spam folders but until today, Sep 24th, I did not get any reply at all. That's why, against all hope, I just wrote another message, explicitly but politely asking them to please explain to me how they can legally issue a new license, not being the copyright owner of the subscriber content.

However, I don't really expect an answer anymore and I think from the legal department of the Network (or the community department judging by the lack of communication regarding the issue) there is no interest whatsoever to explain the legal reasoning behind the announced re-licensing of the existing content.

Because this might be a breach of the copyright and because a re-licensing might not only have positive repercussions, I also wrote to the Free Software Foundation (info at fsf dot org) just now and explained the situation, asking for their professional evaluation of the situation as well as publicity in case they agree with my depiction of the case.

Nothing more I can do to clarify the issue short of going to court and that is unfortunately very expensive and I could not afford that. Maybe a larger amount publicity (Twitter, Reddit, ...) would do some good there, not sure though.

If ever any late response arrives from the legal department, I will add it here, but I doubt it will happen.

On Sep 25th, I also wrote to the EFF (info at eff org) with a message similar to the one I sent to the FSF.

On Sep 27th, I received a reply from the EFF. They could not be an attorney in this matter, but can facilitate the contact to their cooperating attorneys. For information (I will not use the offer), I attach the essentials of the reply (I would rather attach a reply from the Network).

[..] While EFF cannot be your attorney for this matter, we can offer to try to facilitate a referral to one of our Cooperating Attorneys for you to find you someone who could dig into this with you a bit more. Our Cooperating Attorneys mailing list is composed of attorneys who have volunteered to offer help in cases the EFF cannot handle itself. Information about the list can be found at https://www.eff.org/pages/legal-assistance#coopattys.

If you would like a referral, please explicitly confirm in your reply that you would like me to post a referral to the Cooperating Attorneys list and include the following, even if you have already told me:

  1. Where you are located.
  2. Who the opposing party is and where the opposing party is located.
  3. A brief description of the situation and the legal assistance you are seeking.
  4. Whether you can pay for representation. We cannot guarantee pro bono help.
  5. If any of the info you've given to me should not be sent to the list, please let me know since we cannot guarantee that someone related to the opposing party is not on the list. [..]

When we hear back from someone who's interested in working with you, we will forward you their contact information. We can't guarantee that we'll be able to refer you, but we're happy to try. Please also note that we do not and cannot screen the attorneys on our referral list. In most states you can check with the State Bar website for the current status and record of lawyers in that state, but you need to make your own judgment about which attorney is right for you. [..]

On 22th of November I got a late response from the FSF (by Ineiev) where they apologized for the late reply (being a "nonprofit organization with very limited resources"), which is more than I ever received from the legal department of StackOverflow (nothing so far).

They stated:

Irrespectively of who the copyright holders of the work in question are, the CC-BY-SA-3.0 section 4b(ii) grants the permission to distribute the work under any later version of the license, so anyone may choose a newer license when distributing.

-- I am not a lawyer, this is not a legal advice.

This is identical to the answer by trickly here, who draw inspiration from Can I “upgrade” the version of CC BY-SA from 3.0 to 4.0 in my modification?, where however the highest voted answer by user amon says that CC are upwards compatible but do not easily migrate.

On 20th January 2020, I replied to the FSF along the lines of explaining the reasoning of these answers here and why it would disagree with their advice and asking if this would any difference to their opinion.

March 1st 2020: Until now, I did not receive anything from SE Inc. and I did not receive another reply from the FSF.

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    The lack of responses is a bit disappointing, but that's companies for you: they want something from you, they are quick; you want something from them, no way. – Trilarion Sep 24 '19 at 12:16
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    I'm not sure the FSF would be very interested. Have you considered writing to the Electronic Frontier Foundation, though? – user Sep 25 '19 at 8:21
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    Are we sure they still have a legal department? – Zoe the 1337 Princess Sep 25 '19 at 9:57
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    @aCVn Thanks for the suggestion. The EFF homepage looks like they could be helpful. I have written them. – Trilarion Sep 25 '19 at 10:45
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    @PrincessOlivia The terms of service mention this email address specifically in case of requests for information. The StackExchange Network is a rather big company, they should have a legal department. The current simplest explanation is that they don't want to talk with us. – Trilarion Sep 25 '19 at 10:49
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    Maybe we need to start a gofundme to build a legal fund. I know I opted out of arbitration and AFAIK, anyone in the EU does not have to to abide by the mandatory arbitration clause. – NathanOliver Sep 25 '19 at 13:00
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    For what it's worth, I have contacted Stack Exchange directly twice and received no response either. I intend on contacting an attorney if they do not respond by tomorrow evening. The EFF (and possibly FSF) are good contacts to have as well. I made a meta post that is highly upvoted (a score double that of the announcement), and it has received no response either. They have even refused to "feature" it on meta, providing no explanation. – jhpratt Sep 27 '19 at 3:05
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    @jhpratt Your and my experiences seem to be consistent. If you really contact an attorney, please don't hesitate to ask for financial help here. – Trilarion Sep 27 '19 at 8:23
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    @jhpratt if there is a need to raise funds for a lawyer, I'd be willing to donate to a gofundme page or petition – cegfault Sep 27 '19 at 15:50
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    @jhpratt Do you have any update on this? – Lightness Races in Orbit Sep 30 '19 at 10:44
  • @LightnessRacesinOrbit I have not yet heard back. – jhpratt Sep 30 '19 at 17:11
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    @cegfault Just launched a GoFundMe. link. Share as you want, but I won't be making a post here on meta. – jhpratt Nov 7 '19 at 22:45
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    @Trilarion Just launched a GoFundMe. link. Share as you want, but I won't be making a post here on meta. – jhpratt Nov 7 '19 at 22:45
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    @NathanOliver-ReinstateMonica Just launched a GoFundMe. link. Share as you want, but I won't be making a post here on meta. – jhpratt Nov 7 '19 at 22:45
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    @LightnessRaceswithMonica Just launched a GoFundMe. link. Share as you want, but I won't be making a post here on meta. – jhpratt Nov 7 '19 at 22:45

I'm no lawyer, but it seems to me that Stack Exchange is running a serious risk of losing their rights to ALL content because of their failure to address this issue.

As is clearly stated in the Creative Commons FAQ:

How can I lose my rights under a Creative Commons license? If that happens, how do I get them back?

All of the CC licenses terminate if you fail to follow the license conditions. If this happens, you no longer have a license to use the material.

In the 4.0 licenses, your rights under the license are automatically reinstated if you correct this failure within 30 days of discovering the violation (either on your own or because the licensor or someone else has told you). Under the 3.0 and earlier licenses, there is no automatic reinstatement.

If you have lost your rights under a CC license and are not entitled to automatic reinstatement, you may regain your rights under the license if the licensor expressly grants you permission. You cannot simply re-download the material to get a new license.

Note that you may still be liable for damages for copyright infringement for the period where you were not in compliance with the license.

As others have pointed out, Stack Exchange does not have the right to unilaterally change the license of previously submitted content without our approval. In fact, your attempt to do so might revoke your rights to the content altogether.

  • 2
    That's what I've been wondering as well. Would be very interesting if that was possible. What if enough users make a case out of this, and SE would be forced to delete millions of questions and answers? – GolezTrol Oct 2 '19 at 14:12
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    If that were to happen, @GolezTrol, it would be devastating... for everyone. Stack Overflow (and to a lesser extent the rest of SE) has a reasonable claim on being one of the most important sites on the Internet, potentially even the single most important site (on the grounds that many important companies, including ones providing some of the other most important sites, use SO themselves; it's highly likely that SO is in part responsible for solving problems they faced while designing/maintaining those sites, and thus in part responsible for their ongoing functionality and usefulness). – Justin Time - Reinstate Monica Oct 2 '19 at 18:44
  • If we lose it, and/or the knowledge contained therein... there is actually a very good chance that it's only a matter of time until development slows significantly worldwide. Many problems would need to have their solutions re-engineered, and a new resource/solution collection would need to be provided; sadly, the latter would very likely be fractured, spread across many sites instead of mostly being on one. – Justin Time - Reinstate Monica Oct 2 '19 at 18:47
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    @JustinTime It's not that bad. 99% of the content on SO can be found as well on any of the next search results that come after SO. SO is good at SEO (better than at building a search engine), and at providing many different entry points to that same information, so it's easier to find. Most of the information is in no way lost, though. – GolezTrol Oct 2 '19 at 19:41
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    @JustinTime all stack exchange data is publicly released in data dumps over bittorrent. It's not possible for them to delete the data. This (a) makes their legal standing way way way worse because they can't undo the harm, and (b) even if they delete questions and answers on the site, that content is still publicly available worldwide via bittorrent – cegfault Oct 2 '19 at 20:51
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    @cegfault That last comment is an over-reaction. The bit-torrented data dumps were made available under (the correct) CC BY-SA 3.0, so they do not represent a license violation. However, any future dumps of old content released under 4.0 (almost certainly) do represent a violation; it's unclear to me where it puts SE if those dumps are downloaded by others and redistributed under the 4.0 license. – E.P. Oct 2 '19 at 21:55
  • I'm looking at what would happen if the data actually was lost, @GolezTrol, if they were forced (or chose) to delete it in a way that rendered it unrecoverable. So, basically examining the worst-case (and IMO most likely) result of them truly being forced to delete all that data. I'll admit I wasn't actually aware of the data dumps cegfault mentioned, though, they're a big relief. – Justin Time - Reinstate Monica Oct 2 '19 at 22:41
  • @JustinTime I don't think it would take very long at all for SO to get totally MySpaced by a new coding skillshare site... hopefully one lacking analogues to all the cringeworthy SEs. – StackOverthrow Oct 2 '19 at 23:48
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    @E.P. I mistakenly thought the latest data dump was after Sep 5 and therefore under 4.0, but I was wrong; you are correct the last one was under 3.0 ... they probably won't release a 4.0 dump until December so they have time. In any case, the point that they cannot truly purge data from the past. That is, if people demand millions of questions/answers get purged, they'd be purged only from the website, not from the torrent. – cegfault Oct 3 '19 at 11:58
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    @JustinTime I meant to say that there is very little information that exists exclusively on Stack Overflow (or other Stack Exchange sites). There is still official documentation, books, blogs, other forums and Q&A sites and so on. SO is very searchable, because every question has been asked and answered dozens of times, but it's in no way the only source of information, and most of the answers here are adaptations of content that exists elsewhere, so if they would be forced to delete all that data, and the dumps wouldn't be there, it's still not like everybody would be completely lost. – GolezTrol Oct 4 '19 at 11:49
  • That's fair, @GolezTrol. Hopefully all of the other sources are properly licensed, too! 😛 – Justin Time - Reinstate Monica Oct 5 '19 at 21:56
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    Based on my reading of BY-SA-3.0, SE has not only already terminated its rights under CC, furthermore they never had them in the first place, because they claim content is licensed "perpetually and irrevocably" even though BY-SA-3.0 has an explicit termination clause. "You may Distribute or Publicly Perform the Work only under the terms of this License. …You must keep intact all notices that refer to this License...with every copy of the Work You Distribute...." and "This License and the rights granted hereunder will terminate automatically upon any breach by You of the terms of this License." – Clement Cherlin Oct 11 '19 at 21:01
  • Except that we all grant SE another separate license to use the content in any way they please, regardless of CC. So they'll be fine. – JonathanReez Nov 6 '19 at 0:53

While we are here ....

This is related enough to be mentioned here.
When images are copied to Imgur they are not only notionally assigned CC-by-whatever-the-current-flavour-is rights BUT also are subject to Imgur's TOS for unpaid Imgur posts. These are draconian. I raised this issue some years ago and was assured at the time that the Imgur conditions applied to paid Imgur contributions would be applied. However, in 'no time flat' the language used made it clear that committing an image to Imgur storage was (allegedly) waiving your rights to it.

But wait - it's worse ... If you LINK to an image because embedding it would result in SE CC-by-xxx ing it, and Imgur making off with it, and if somebody then converts the link to an Imgur stored image, as people'helpfully' do on an ongoing basis, then notionally the helpful editor has assigned CC-by-xxx to your image and given Imgur the right to have their irrevocable way with it without you knowing, let alone having been asked what you think.


Rene helpfully located my question and its "answer" from 7 years ago here

There Imgur is cited as saying
"Although we don't sell the images or grant usage for them at all, it is in the terms that we have the right to do so." That is what I was querying then.
Does this apply now?

'Back then', Jaydies, on behalf of SE said "We have a contract with Imgur LLC that explicitly states:

Imgur will make no claim of copyright to any images stored by SE on the Image Server (other than Imgur's own copyrighted images and other works, if any)."

But, the question is not whether they own copyright but whether they have or claim to have been granted the right to have their way with images in an unlimited manner. That they believed that they had the right then appears to have been the case, quite regardless of copyright.

"While we don't .... we have the right ..." is precisely what the current question is attempting to deal with.

Also relevant:

imgur, copyrighted images from the web, and imgur accounts

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    I would expect that a third party, such as your mentioned helpful editor, cannot give Imgur, nor any other entity, a valid license to the image as it is not theirs to license in the first place. That of course raises the new question about whether they have the right to upload it to Imgur at all, or if that should technically constitute copyright infringement. (By whom; the editor, or Imgur, or both?) – user Sep 8 '19 at 20:08
  • @aCVn I agree with your points. These have been raised directly or by implication in past discussions afaik. This does not stop people giving Imgur an invalid licence (and it happens), both to images owned by SE posters and to images they have cited. ||We also seem to have reverted to the state where "Imgur OWNS your images" once they are posted to Imgur, even though they had CCbyxxx status while transiting SE. [People posting images to Imgur using a free account are effectively assigning open slather rights to them in perpetuity. ] ... – Russell McMahon Sep 9 '19 at 7:03
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    @aCVn ... AFAIK the SE status of Imgur hosted images is the same. I was assured that this would be changed when I noted it some while ago but we seem to be back where we were.]. – Russell McMahon Sep 9 '19 at 7:04
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    I assume SE pays imgur for their service so I doubt the "unpaid" claim is at play here. Imgur will make no claim of copyright to any images stored by SE on the Image Server (other than Imgur's own copyrighted images and other works, if any) source – rene Sep 9 '19 at 16:29
  • @rene I'll leave this here incomplete and start another comment: I discussed this with [person at other end of a link]. The written terms were as for the unpaid service. | I was assued by an (as I recall) SE person that this would be changed. Indications have been for some while that the wording is now and/or still as it was. | A wade through the Imgur terms that were applied made it clear that they for practical purposes owned the copyright. – Russell McMahon Sep 9 '19 at 19:14
  • @Rene That is (as you will no doubt be aware) my original query from 7! years ago. | Looking at the edit history (which I just did) shows that some of the explicit Imgur comments have been edited out of my post and it is uncertain what the situation is BUT it looks as though it applies as I say above. Back then Imgur said: "Although we don't sell the images or grant usage for them at all, it is in the terms that we have the right to do so. If you delete your image, we no longer have the right, so it is perpetual for the duration of its time on our website.". BUT they also note that on ... – Russell McMahon Sep 9 '19 at 19:20
  • @rene ... free accounts images are HIDDEN (not deleted) so the last N only are visible. To delete them you'd have to keep track of the ones visible and may or may not be able to locate the hidden ones. || If we are having this discussion re V3 to V4 licence change and whether it is potentially onerous or whether the V3 licence prevents a change to V4 without user permission - the WHY do we think it's clear that the SE site CC (3 or 4 or ?) licence prevents Imgur's terms applying? – Russell McMahon Sep 9 '19 at 19:25
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    Again: IMGUR themselves said "Although we don't sell the images or grant usage for them at all, it is in the terms that we have the right to do so." – Russell McMahon Sep 9 '19 at 19:25
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    What is the source for the claimed statement from Imgur in your question that you keep repeating? Who asked them, what exactly they asked them, and where is it recorded? There is an actual answer posted by an actual Imgur employee that says something completely different. – Emil Jeřábek Sep 10 '19 at 8:24
  • @EmilJeřábek 1. Did you read my post from 7 years ago [here]()? 2. Please provide a link to and identify what you mean when you say "There is an actual answerposted by an actual imgur employee ..." 3. Have you noted that you retaining copyright to your material does not stop imgur doing whatsoever they wish with it IF you licence them to do so? ... – Russell McMahon Sep 10 '19 at 14:07
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    What you just quoted are terms of Imgur’s public free hosting service. They are irrelevant to the usage of SE’s paid private Imgur account, whose terms of service are given solely by the contract between SE and Imgur. Your 7 year old question is answered by authoritative answers of both an SE emplyee (Jaidles) and an Imgur employee (rrrah), who make it clear that as per the contract, no rights to the hosted images are transfered to Imgur. As far as I can see, you are just spreading baseless FUD. – Emil Jeřábek Sep 10 '19 at 16:14
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    You have not provided any reference whatsoever for your claim in meta.stackexchange.com/q/137714 that “Although we don't sell the images or grant usage for them at all, it is in the terms that we have the right to do so” (that you keep repeating here), nor you have answered any questions that I raised about it. This is FUD plain and simple. The two answers that I mentioned are also in meta.stackexchange.com/q/137714 . I assumed that you read that, since you keep telling everyone else to do so. – Emil Jeřábek Sep 11 '19 at 6:35
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    @EmilJeřábek I'd hoped we might be able to settle down to a somewhat more reasoned discourse. || Thanks for the source of the 'rrrah' comment - I'd missed that name. She quotes a lawyer reiterating what Michael Pryor said - and then quotes an excellent example of my XXX / YYY dichotomy. | She says "We have a contract with Imgur LLC that explicitly states: Imgur will make no claim of copyright to any images stored by SE on the Image Server (other than Imgur's own copyrighted images and other works, if any)." || This in NO WAY says that Imgur does not claim the right to use your images ... – Russell McMahon Sep 11 '19 at 11:02
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    ... in any way they wish - it just says that you retain copyright. That matches my above XXX / YYY case. [Copyright retention is not necessarily not loss of all rights] || I will be very happy if someone authoritative in one place provides links to the agreements that exist. 'Simply' stating that "we have agreed xxx" which implies "yyy" and asking people to take it on trust (with or without the statement that I do NOT at present have a link to) does not make the claims true. As above, I am not saying that purposeful falsehood is intended. – Russell McMahon Sep 11 '19 at 11:07
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    @Zhaph-BenDuguid " ... Not that ..."-> There's always "take down", but you'd hope that i- there would not be a need in the 1st place ii - the system would be able to allow deletions of additions that were manifestly improper . – Russell McMahon Sep 26 '19 at 9:08

I think it would be better to provide a choice (like YouTube, DeviantArt and some other websites do): CC BY-SA 4.0 as default value for new content, and 3.0 for old content. And of course MIT :)

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    In theory, this could be a good solution, especially if the selected license is shown somewhat prominently along with the answer text. In practice, it seems to create uncertainties of its own. What if I change my mind after posting the answer? (In either direction: less restrictive to more restrictive, or the other way around.) What if I change my mind back again later? What if someone else makes an edit and they want their (perhaps substantial) edit to be under a different license? What if an unrelated third party changes the license? (You'd hope that doesn't happen, but in theory it could.) – user Sep 7 '19 at 10:53
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    @aCVn you cannot revoke any of the licenses, so changing your mind is irrelevant – OrangeDog Sep 7 '19 at 11:41
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    @aCVn just see solutions in any existing open-source project, for example Linux that has many edits :) Changing a license can simply be disabled after publication. – andreymal Sep 7 '19 at 14:17
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    I like this idea for most sites, but there's a problem. For a post with a block of code that meets the bar for copyright protection, you would probably need two licenses. The CC licenses are inappropriate for code, and code licenses (like MIT) are inappropriate for text and images or combined work of text, images, and code. – Thomas Owens Sep 7 '19 at 15:08
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    @andreymal The Linux kernel is for all intents and purposes stuck at GPL 2 only precisely because that's the license that was set early on (and as I recall, even that was a relicense from Linus' original, more restrictive license). That's a big reason why a lot of free software that's under the GPL specify "GPL/LGPL/AGPL/... version X, or at your option any later version", for some value of X. – user Sep 8 '19 at 10:45
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    @OrangeDog Two words: dual licensing. Though you're right, rescinding an already offered license is a different kettle of fish. It raises the question though what happens if someone only comes across the content after the license change. Generally, I stand by my main point: good idea in theory, very complex in practice. – user Sep 8 '19 at 10:46
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    @aCVn "What if I change my mind after posting the answer?" -> Toooo late except if the old terms are not violated by anything in by the new. . | "What if I change my mind back again later?" -> As above. "What if someone else makes an edit and they want their (perhaps substantial) edit to be under a different license?" -> As above only. All "GPL" type licences expressly state that alterations editions ... must follow the original terms AND perpetuate them. "What if an unrelated third party changes the license?"-> Unpermitted and it can't legally in any way EXCEPT as above. – Russell McMahon Sep 9 '19 at 8:55
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    So, we will allow clueless newbies that can't write anything in proper English asking why their nooby javascript code prints "undefined" to choose how they want to license their question including all the code that they just copied from somewhere else in the internet, even if they don't know nor care anything about licensing? – Victor Stafusa Sep 9 '19 at 17:05
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    @aCVn, Linus Torvalds hates GPLv3, so it's disingenuous to claim Linux is stuck at GPLv2 only because that's what was chosen early on. – Wildcard Sep 9 '19 at 19:31

I wonder if this means that compatibility of the content with Wikipedia content is broken now. I think Wikipedia still uses CC-BY-SA-3.0 and typically these licenses are not backward compatible.

Could I use newly generated content from here still in Wikipedia?

If this isn't the case, I don't like it.

  • 4
    So it is, link: en.wikipedia.org/wiki/… – dbc Sep 6 '19 at 17:48
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    "According to the WMF legal team, CC BY-SA 4.0 is not backwards compatible with CC BY-SA 3.0. Therefore, mixing text licenses under 3.0 and 4.0 would be problematic" - WP:COPYPASTE – OrangeDog Sep 7 '19 at 11:38
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    In general you couldn't use content from here in Wikipedia anyway, due to WP:SOURCE. – OrangeDog Sep 9 '19 at 14:04
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    @OrangeDog Do you mean that SO is not authoritative? At least for the more useful questions and answers the content is made by professionals in the field. – Trilarion Sep 10 '19 at 8:25
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    @Trilarion there are very very few answers that would be suitable encyclopaedia content, are not tertiary sources themselves, do not reference Wikipedia and are written by verifiable authorities. – OrangeDog Sep 10 '19 at 8:29
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    @OrangeDog Jon Skeet has hundreds or thousands of answers with a score higher than 100 alone. Would he count as a verifiable authority? I don't know. I would probably count him as verifiable but not everything he posted here as notable. – Trilarion Sep 10 '19 at 9:49
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    @Trilarion read the Wikipedia policy. You can cite his books no problem. You can legally copy his (CC-BY-SA 3.0) answers into Wikipedia, but you'd need citations for that content beyond the content itself. – OrangeDog Sep 10 '19 at 9:54
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    @OrangeDog: There are plenty of secondary sources (linking directly to language specifications, which are primary by definition). Some of those answers are even written by the very same people who co-wrote the primary source. IMO, the chief problem with using SO content Wikipedia would be a disagreement what stands above primary sources. On SO, that would be math and logic, on WP it's generally the page owner's opinion. – MSalters - reinstate Monica Sep 17 '19 at 13:40

Can you please at this time also remove the trademark violating demand that attribution be given in specific bespoke ways from the footer link and help centre, as I believe was your plan when the new TOS was adopted. (TL chat link).


I see that the link at the bottom of Area 51 now goes to version 4.0 of the license, instead of version 2.5 as it did previously.

However, the footer continues to specify the name of the license as "CC-Wiki", which is an old, deprecated alias name of the CC BY-SA license that was discontinued back when the 3.0 licenses rolled out:

CC-Wiki name used on Area 51

Can that please be changed to say "CC BY-SA 4.0" instead of "CC-Wiki"?

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    Or put it back to what it was before until the legal problems with this change have been resolved. – Lightness Races in Orbit Sep 9 '19 at 22:00

The Help Centre links to the CC BY-SA 3.0 license and also needs updating.

  • curiousdannii, these short link only answers end up in the VLQ. This would have been better as a comment, even using the Contact Link; this update has been done, in any event. – Rob Sep 30 '20 at 12:46
  • @Rob normal rules don't apply to Meta, and especially not to announcements like this. The company was using this discussion like a bug tracker, and requested feedback. Cross referencing other feedback is perfectly fine. If it had been a comment it would've been lost and probably deleted as they periodically prune the comments. – curiousdannii Sep 30 '20 at 22:21

The Terms of service back in Nov 5 2017 were (bold emphasis mine)

You agree that all Subscriber Content that You contribute to the Network is perpetually and irrevocably licensed to Stack Exchange under the Creative Commons Attribution Share Alike license. You grant Stack Exchange the perpetual and irrevocable right and license to use, copy, cache, publish, display, distribute, modify, create derivative works and store such Subscriber Content and, except as otherwise set forth herein, to allow others to do so in any medium now known or hereinafter developed (“Content License”) in order to provide the Services, even if such Subscriber Content has been contributed and subsequently removed by You.

So all subscribers are granting content to Stack Overflow under two licenses :

  • Creative Commons Attribution Share Alike
  • The previous quoted paragraph starting with "You grant Stack Exchange..."

The current text is different:

You agree that any and all content, including without limitation any and all text, graphics, logos, tools, photographs, images, illustrations, software or source code, audio and video, animations, and product feedback (collectively, “Content”) that you provide to the public Network (collectively, “Subscriber Content”), is perpetually and irrevocably licensed to Stack Overflow on a worldwide, royalty-free, non-exclusive basis pursuant to Creative Commons licensing terms (CC-BY-SA), and you grant Stack Overflow the perpetual and irrevocable right and license to access, use, process, copy, distribute, export, display and to commercially exploit such Subscriber Content, even if such Subscriber Content has been contributed and subsequently removed by you as reasonably necessary to, for example (without limitation):

But it is still the same two licenses.

As a non-lawyer I get the impression that the second license pretty much lets Stack Overflow do anything they want with subscriber content including but not limited to publish it under CC-BY-SA-4.0 without agreement from original poster.

Though it can be argued that neither of those paragraphs include the term "relicense". We are granting only the right to "use, copy, cache, publish, display, distribute, modify, create derivative works, store and, [...], to allow others to do so [...]". So that and only that, nowhere are we granting the right to do any of those things under different conditions, which is what a change of license means.

Which interpretation is right about this 2nd license allowing the unilateral change to CC-BY-SA-4.0 can only really be discerned by a lawyer judge. But in both cases I consider the 2nd license to be excessive and granting way too many privileges to Stack Overflow while stripping contributors from the protections that CC-BY-SA aims to achieve.

Which is why I propose:

  • Granting of 2nd license of the ToS should be removed from now onwards. Stack Overflow should not have a privileged license which other users don't have. As a user of SO I contribute content as a means to share knowledge equally with everyone. SO is a medium and I don't mind if they profit from providing such medium, we also profit from using it. But I most certainly dislike contributing while being stripped of CC-BY-SA protections by having to agree to this 2nd license. One of those CC-BY-SA protections being that license terms can't be changed by the licensee (this protection is stated in Section 4 of CC-BY-SA 3.0) .
  • ToS should explicitly state that content is provided under CC-BY-SA versionX or later. So as to not encounter ourselves in the potential future situation of being stuck with a then old CC-BY-SA version with known problems.
  • 3
    If you disagreed with the much more permissive licence SE has, you're free to post elsewhere. Its just something that I suspect gives them leeway and what they need to do, well stuff like this – Journeyman Geek Sep 8 '19 at 13:42
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    There is an important distinction. Even with the additional license (which should be nuked from orbit, I agree), I grant Stack Exchange the right to do whatever they do with my posts. Nowhere is it written that this right is transferable. If SE republishes my content under CC-BY-SA-4.0, they are not only displaying, exploiting, etc. my work, which is their right, but they are also granting everyone else the right to do the same under that license. And they can't do this: they don't own these posts, they just have obtained special permissions on them by their rightful owner. – Federico Poloni Sep 8 '19 at 15:14
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    @FedericoPoloni That is a very good point. Indeed nowhere does it say "relicense". I'm going to incorporate that in my answer. – Anonymous Coward Sep 8 '19 at 21:40
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  • 1
    @FedericoPoloni if I'm reading the terms correctly, it does let them relicense it as they get the full rights to the work. A lawyer would be required. – JonathanReez Sep 25 '19 at 22:16

Stack Exchange and Stack Overflow have moved to CC BY-SA 4.0

Wait… what?

Funny how one has to learn about this stuff months after it happened, just because one accidentally stumbles upon some link in the comment section of another meta post. That’s not OK. Also, I didn’t get any email telling me about this change and I wasn’t asked if I am OK with my content being re-licensed either. (Sending a typical system email notification to existing users isn't that hard — SE does that multiple times a week; eg when your posts get a comment.)

To react to this MetaSE post, I feel forced post my two cents here. Not only because this Q&A seems to be the appropriate place to do so, but also to clarify the legal parts that Stack Exchange Inc. obviously ignores.

License Notice

On September 5, 2019, Stack Exchange, Inc. declared it re-licensed all content from CC BY-SA 3.0 to CC BY-SA 4.0, including all previous contributions. The network's terms of service allows Stack Exchange Inc to use the licensed material made available to them, as users provide a non-exclusive license to allow for commercial use among other purposes. However, it also makes clear that content is provided to other people viewing the site under the CC BY-SA license. Stack Exchange Inc's re-licensing announcement displayed at Stack Exchange and Stack Overflow have moved to CC BY-SA 4.0 states and confirms that content was previously licensed under version 3.0. Pursuant to that license.

Stack Exchange Inc does not have the right to unilaterally change the license of previously submitted content. Since I am the original copyright holder of my posts, Stack Exchange Inc. needs my permission to re-license the content I made available under the license in effect and mutually agreed upon at the time of posting. Without my permission to change the license, all my content remains licensed under CC BY-SA 3.0.

To be clear: I did not and do not intend to give Stack Exchange Inc. active or passive permission to re-license my content to any other license or license version; resulting in the fact that CC BY-SA 3.0 remains in effect for all my contributions.

As a reminder: Stack Exchange Inc is licensee of the content I posted here. It's not the other way around.

Under no applicable law — neither international laws, nor US laws, nor any EU laws (I, the licensor, am located in the EU) — are licensees permitted to bluntly re-license work which was provided to under a specific license and license version by the licensor — me .

Stack Exchange Inc. is generally welcome to express their objections and/or seek re-licensing allowance by contacting the copyright holder – me – in writing via email and/or postal mail. I would like to remind Stack Exchange Inc. about the fact that Stack Exchange Inc. has my email address on file. Any related contacting efforts via the Stack Exchange network itself (eg the internal website messaging system, website chat, MetaSE posts like this Q&A, etc), or any other means of communication (eg phone, telefax, Twitter messages, etc), can and will be ignored. Simpler stated: communication about legal issues or license changes will only be accepted in writing, using the usual communication means that businesses normally use when discussing such changes and potentially targettinf contract changes.


Based on the legal issues Stack Exchange Inc. introduced with their sneaky and unacceptable “re-licensing” attempt and the following related action(s), I am herewith halting all further contributions to the Stack Exchange network websites. This is not likely to change, unless Stack Exchange Inc. resolves the re-licensing issuey they introduced by not asking for my consent as the copyright holder and licensor.

Reserved Rights

Being the copyright holder amd licensor of my posted content, it should be logic and clear that I generally reserve all rights to enforce and secure my rights now and at any given time in the future if I deem it to be necessary to do so to protect my intellectual property against misuse by Stack Exchange Inc. or any other licensee.

The licensee — in this case Stack Exchange Inc. — is meanwhile given time to revert the unacceptable re-licensing attempt, or to seek permission from me to use my content under another llicense on yet-to-be-discussed terms and conditions.

Nota Bene

Last but not least, I herewith benevolently remind Stack Exhchange Inc that one-sided contract changes are against both national as well as international laws, and therefore generally void. Ignorance of that fact does not magically legalize unauthorized license change attempts.

No! That's not how this works!


For what it's worth, here's how we deal with this in the Fedora Project. We have a contributor agreement ­which provides for a default license for any contributions which do not already have one. For code, that's currently MIT; for content, it's CC-BY-SA 3.0 supplemented by Moral Rights Clause Waiver and GPL Relicensing Permission. But we also say:

The Fedora Council may, by public announcement, subsequently designate an additional or alternative default license for a given category of Contribution (a "Later Default License"). A Later Default License shall be chosen from the appropriate categorical sublist of Acceptable Licenses For Fedora.

Once a Later Default License has been designated, Your Unlicensed Contribution shall also be licensed to the Fedora Community under that Later Default License. Such designation shall not affect the continuing applicability of the Current Default License to Your Contribution.

You consent to having Fedora provide reasonable notice of Your licensing of Your Contribution under the Current Default License (and, if applicable, a Later Default License) in a manner determined by Fedora.

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    This would've been a great thing to include in the TOS before the license change. – curiousdannii Oct 3 '19 at 14:28

Sticks in my craw to ask questions in an answer, but...

What's the practical difference between 3.0 and 4.0?

What protections does it lend me as a content creator, and do I lose anything from the change?

  • 6
    One important change is that it supplies a 30-day grace period for people who use the work without following the license to correct the violation. – Sonic the Anonymous Hedgehog Sep 8 '19 at 17:08
  • 1
    Another difference is that you can use CC 3.0 content to write a CC 4.0 answer (assuming they're both CC-BY-SA specifically) but not the other way around. So if we stayed on 3.0, eventually it would become harder to write SE answers because we'd be able to reuse less content. However, that has nothing to do with relicensing old questions and answers, which is what all the fuss seems to be about. – Kevin Sep 9 '19 at 15:53
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    The first undeleted comment under the question currently links to a 'whats new in 4.0' page, btw. – TylerH Sep 9 '19 at 15:58
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    The biggest change in terms of "rights lost" is that under 4.0, you agree to waive database and moral rights to the greatest extent possible. In terms of protections, an end user explicitly gains the right to break any DRM applied, while an author gains the right to include a URI as part of the attribution, and to request removal of attribution at any time for any reason. Most of the rest of the changes are minor adjustments to make the CC licenses easier to comply with in various situations. – Mark Sep 9 '19 at 20:10
  • @Mark, I read prohibited in: "When a database is subject to sui generis database rights, extracting and reusing a substantial portion of the database contents is prohibited absent some express exception", so I wonder if my country of origin matters? The EU copyright laws do impose sui generis database rights, but if I somehow were to share a huge database on SE (true content; not just a link to some EU server), then maybe USA laws apply? – Arjan Oct 5 '19 at 11:35

If this is being done to bring the licensing footer, TOS, and everything else into agreement, well... that's a not awful reason, though it is problematic.

There is some suggestion that this is being done to have everything under a better and more consistent license and changing the license on past contributions... that gets problematic. If Stack Overflow corporate is claiming that they have the rights to relicense contributions under a different creative commons license, do they have permissions to relicense under a 5.0 version in the future (that may be objectionable) or under CC0 now?

This strongly echos the GPL and that there are people who agree with GPL2 but not GPL3.

If Stack Overflow claims the rights to relicense from CC 3.0 to CC 4.0, do they also have the rights to relicense to CC0? Or CC-BY-NC?

If there is permission to relicense to a specific set of licenses, where is this spelled out?

If there is permission to relicense to any license, where is this spelled out?

Saying "we're doing this, its good for you, trust us..." well, a lot of trust has been burnt in the past and this isn't likely helping.

  • 4
    "This strongly echos the GPL and that there are people who agree with GPL2 but not GPL3." That particular one is rarely a big problem in practice, though. You generally have two cases with the GPL specifically; licensing under (for example) "GPL v2" (specifying an exact version) or, say, "GPL v2 or, at your option, any later version". In the first case, the version is fixed; in the second case, it allows the licensee to choose, but said licensee has to comply with the full terms of the license version they choose. – user Sep 8 '19 at 20:14

They had a license-change case also with OpenZFS (after ZFS was made closed source), and the question has been raised why the OpenZFS develoeprs didn't take the chance to change the license to fit with Linux. The answer according to the OpenZFS website was that:

...changing the license would involve contacting anyone who contributed code to the current OpenZFS implementation (including the initial, common ZFS code till OpenSolaris) and get their permission to change the license. Since this job is near impossible (because some contributors may be dead or hard to find), they have decided to keep the license they have.

See also their Wiki FAQ: http://www.open-zfs.org/wiki/FAQ#Do_you_plan_to_release_OpenZFS_under_a_license_other_than_the_CDDL.3F


(Since there's a potential point of confusion - I'm a community moderator here and my viewpoints are in no way official except when quoting an official source, neither do they represent the views of the moderation team or anyone other than myself. I know as much, or as little as any of you.)

Since this came up during a conversation on chat, and there's no official answer pointing this out...

We've actually had a license switch before. Amusingly, it was similarly messy with two or three different licence names. There was a lot less fuss then and Stack Exchange apparently survived this.

To quote Shog on chat:

Because, that's really what the CC license is about here: protecting y'all from us. Or from whoever buys us. If you look at the history that motivated licenses like this, that was generally the thing that happened: company solicits user contributions, then makes 'em private, then sues former users for trying to reuse their own content.

The main goal here is so Stack Overflow (the company) or their successors cannot take their ball and go home. They can't do a hyphen site, hide everything we've done so far behind a paywall then go full evil and try to sue users for posting their own content as was on SE.

So, let's talk about some practical considerations. I've been under the impression so far that we license our content to SE - under the understanding that it would be released under the CC BY-SA license and other additional conditions - as per this other answer.

First, it would be practically impossible to contact every single user who has ever contributed anywhere on the network to get an agreement.

If we're looking at extreme legalistic interpretations...let's start with:

Stack Overflow reserves the right, at its discretion, to modify these Public Network Terms at any time by posting revised Public Network Terms on the public Network and by providing notice via e-mail, where possible, or on the public Network.

And well, they provided notice on the public network that they were changing the version of the CC license in use. In theory, and in practice, I don't think anyone would fault anyone else for reproducing content as per the CC licence in use at the time when something was republished.

There's no major change in how we post things and how SE uses them - only how a third party is allowed to use them. This is pretty important. I doubt anyone would fault the use of the CC-Wiki or 2.5 before April 8, 2011, and 3.0 up until this change.

And practically, by insisting that SE gets explicit permission from every single contributor, well that's throwing a brick wall in front of updating the license version without any real way to get around it. There's literally no room to budge if you take that view.

And fundamentally, outside "they're changing a thing without asking us" I'm unclear as to what's the downside here. It's a newer license covering what you see on the page now if you need to use content you didn't generate.

It's also worth considering how and where these licenses are used - scrapers probably could be a group of people targeted, but otherwise knowledge on SE tends to be used pretty widely with no real barriers.

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    We are not throwing a brick wall in front of updating the license. Stack Exchange threw it themselves by being sloppy when writing the contract: no "3.0 or later" clause, a lot of confusion and unclear terms about which version of the license applies. In this thread we are just pointing at the words that SE wrote in the terms and conditions. – Federico Poloni Sep 9 '19 at 6:21
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    I didn't say we or they. Merely the practical implication of that specific viewpoint. – Journeyman Geek Sep 9 '19 at 6:22
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    Also, note that the clause you mention in your second quotation ("reserves the right ... to modify these Public Network Terms") is not retroactive: a change in the TOS would apply only to newly created content, and is not sufficient to make this relicensing legally sound. – Federico Poloni Sep 9 '19 at 6:24
  • And that's covered by the rest of my answer. That the licence covers content as per the website at the time, that there's precedent and that its not going to retroactively affect content already licenced under previous versions on external sites. – Journeyman Geek Sep 9 '19 at 6:29
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    Side note about "They can't […] hide everything we've done so far behind a paywall." -- Everyone has the right to do this. Only Creative Commons licenses with the "NC" (non commercial) element would prohibit it. – unor Sep 9 '19 at 8:35
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    License confusion like this makes it more complicated for anyone else to legally rehost the content in the event SO becomes paywalled or purchased. I wouldn't put it past an evil buyer to sue over distinguishing 3.0 from 4.0 content, even if only to make the rehoster pay their laywer. If preserving rehostability is the point of the license, this is hurting, not helping. – Jeffrey Bosboom Sep 9 '19 at 8:43
  • @JeffreyBosboom "I doubt anyone would fault the use of the CC-Wiki or 2.5 before April 8, 2011, and 3.0 up until this change." I've tried to address that. – Journeyman Geek Sep 9 '19 at 8:45
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    "There's literally no room to budge if you take that view." What else are contracts for if not to nail down specific parameters so they can't "budge"? If a legal document leaves "no room to budge", well, in the general case that's working as intended, and can be very valuable indeed. If SE wants to change provisions that were already negotiated, well, SE will just need to renegotiate, won't they? That's how contract law works. That's the whole point! – Nathan Tuggy Sep 10 '19 at 3:06
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    "And fundamentally, outside "they're changing a thing without asking us" I'm unclear as to what's the downside here." Creative Commons is designed and intended for the express purpose of making sure (almost) anyone can absolutely rely on being able to legally reuse the material without worrying about someone unilaterally pulling the rug out from under them. If SE thinks they can pull the rug out, even so much as just changing license versions, they are dead wrong and have forgotten the point of the license they chose themselves. – Nathan Tuggy Sep 10 '19 at 3:08
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    @trlkly: There's no way anyone could make "if you don't delete your content you agree to relicense it" fly. Maybe "if you continue to use this site you relicense your content", but there are a lot of users that don't continue to use the site. SE has to either actually get them to agree, or mark their content with a different license. – Nathan Tuggy Sep 16 '19 at 17:28
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    @trlkly Also, the system actively prevents you from deleting quite a lot of your own content, by design. Deletes are only soft deletes; every deleted post is still visible to high-rep users, deleted comments remain visible to moderators, etc. Even if you edit all your questions and answers to replace the content with a suitable permutation of "lalalala" and delete all your comments, the content is still stored in the revision history and posts can be (and often are) restored even by ordinary users. You can request dissociation, but that doesn't in any way affect the content itself. Etc. – user Sep 19 '19 at 9:27
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    There's a very clear course of action for content where they can't contact the original licensor: Delete it. If it's good information, someone else will surely fill the void and provide it again under the new desired license. If it was cruft, it's gone. – user287266 Sep 19 '19 at 19:52
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    @aCVn Yes, something I've come to regret. You don't realize until too late that you don't really get a say in your content anymore, and if you want it gone, too bad, because the ToS prevent you from revoking the license you grant, even if the licensee (SE) has taken actions you want to distance your content from. – user287266 Sep 19 '19 at 19:54
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    I wonder when github will take the same position and relicense all repos hosted on github because it would be too much work to contact all contributors. :P – gman Sep 25 '19 at 12:58
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    How can it "protect us from them" if they are of the opinion they can retroactively change the terms whenever they feel like it? – OrangeDog Oct 2 '19 at 11:08

The post title is a bit confusing, can it be stated; All our network ... in example. (or just the network ...)

I ask as I'am contributor on serverfault.com (same could apply for superuser.com's users), and I seen the new as it's featured. I guess our sites will be on 4.0 version too as inside the post it's told "Stack Exchange Network...", but I had to read it to feel included in the change

I ask as some project are stated for StackOverflow only, and sometime for StackExchange's only, like in your title, but those projects are never done for any sub sites.

A major move like that I hardly imagine that it's not for all the networks.

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    The title of the post says "Stack Exchange and Stack Overflow". Stack Exchange means the whole network, not just the individual site of Stack Overflow. – Rand al'Thor Sep 7 '19 at 15:19
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    @Randal'Thor I think at first it could mean MSE and SO, but yes after reading I seen it’s wrote for all. usually they add network in the title, like seen there; meta.stackexchange.com/questions/300829/… – yagmoth555 Sep 7 '19 at 17:23
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    @Randal'Thor Actually, Stack Overflow is the company and the stackoverflow.com website, Stack Exchange is the network of websites. (from what I understand). stackoverflow.blog/2015/09/15/… – Ismael Miguel Sep 8 '19 at 2:43
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    @IsmaelMiguel Yes. – Rand al'Thor Sep 8 '19 at 7:29
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    @IsmaelMiguel The company is still Stack Exchange Inc (check the footer of this page!), but Stack Overflow is a trading name. – curiousdannii Sep 10 '19 at 15:27

There is something in the ToS that I don't understand.

You agree that any and all content, including without limitation any and all text, graphics, logos, tools, photographs, images, illustrations, software or source code, audio and video, animations, and product feedback (collectively, “Content”) that you provide to the public Network (collectively, “Subscriber Content”), is perpetually and irrevocably licensed to Stack Overflow on a worldwide, royalty-free, non-exclusive basis pursuant to Creative Commons licensing terms (CC-BY-SA), and you grant Stack Overflow the perpetual and irrevocable right and license to access, use, process, copy, distribute, export, display and to commercially exploit such Subscriber Content, even if such Subscriber Content has been contributed and subsequently removed by you as reasonably necessary to...

Does this mean that the content we, users add here belong to Stack Overflow and not to us?

  • 4
    This should probably be a separate question, rather than an answer to this one, but my understanding is that yes, our questions and answers belong to the Stack Exchange community, not ourselves. – F1Krazy Sep 16 '19 at 12:41
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    No - as per... a few answers, it belongs to you, but SE has the right (licence) to use it forever (perpetually) and without a way to go "Nope, I don't want my content there any more". – Journeyman Geek Sep 16 '19 at 14:21
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    Your content belongs to you and you can do with it whatever you want, except revoking the license you gave to StackOverflow. That's the one thing you cannot do. – Trilarion Sep 24 '19 at 11:47
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    @Trilarion Except under the conditions where the license is automatically revoked according to the license itself. – StackOverthrow Oct 2 '19 at 18:05

I was trying to find out whether SO/SE break the license agreement when upgrading. I found this page about upgrading from 3.0 to 4.0. A quote:

Existing content:

  • Who owns the rights?
    • If the publisher, then can relicense under 4.0 as specified above.
    • If the contributors, then need permission to relicense. Without permission (via terms of use or otherwise), then that content remains under prior version. [If this is the case, see the section below about dealing with mixed-version content.]
      • A couple of options for obtaining permission to relicense:
      • upon upload by contributors, have a prompt box to obtain agreement to relicense previous uploads;
      • general outreach to contributors seeking agreement to upgrade. [Note that this is easier to do with discrete artifacts (an article, a photo) as opposed to other contributions such as comments on wikis and similar, where one person's contribution is intermixed with others.]

Long story short, if the publisher (the network) holds the license, they can also do the upgrade. I think it is, and was, in the terms of use that the content users post is licensed to the SE network, so if I understand correctly, the upgrade is legit.

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    Stack Exchange doesn't own our posts, but only has a non-exclusive license to them. – curiousdannii Oct 2 '19 at 11:25
  • @curiousdannii I guess that depends on the interpretation of the Terms. It reads like contributers (users) grant those rights to the publisher (SE). If they were just (re)publishing it under CC, they would't need that big chunk of Terms anyway, since they could already do that. – GolezTrol Oct 2 '19 at 11:42
  • @Golex Perhaps yes. I think they just want to lay it out so there can be no confusion about what "irrevocably" means. – curiousdannii Oct 2 '19 at 11:48
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    I think you can't irrevocably grant usage, since the CC license agreement states that you can lose the license if you break the agreements, so the license itself is explicitly revocable under some circumstances, and saying 'irrevocably' goes right against that. And that's the issue here. If they don't have the rights, their attempt to relicence it is actually a license breach, and would cause SE to basically lose the rights to even use all the content that was posted before under CC 3.0, as cegfault just wrote in their answer right after me. – GolezTrol Oct 2 '19 at 11:59
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    I hope for SE this is not the case, but in the light of recent events of SE becoming evil in their attempts to become overly correct (and dozens of mods being angry), I'm kinda interested to see if the opposite could be true, and if somebody would actually make a case out of this. * popcorn gets * – GolezTrol Oct 2 '19 at 12:01
  • @GolezTrol What do you mean in your comment by "overly correct"? I'm not aware of the events to which you refer. – Basil Bourque Oct 3 '19 at 4:20
  • @BasilBourque These events. – GolezTrol Oct 4 '19 at 11:43
  • So, as I, not at all a lawyer, understand the further portions of the page which you didn't quote, CC-BY-SA 3.0 is forward compatible, which means that adaptations can be released under CC-BY-SA 4.0 but the original can't be changed without permission. So one solution might be to note that content before some date is CC-BY-SA 3.0 and content after it CC-BY-SA 4.0. That could even be marked in the edit history. – mattdm Oct 4 '19 at 22:16
  • @mattdm If you're talking about the heading 'Adaptations of existing content', that still says that the publisher can only do that if they hold the right to the content, so for adaptations, basically the same applies as for existing content. – GolezTrol Oct 5 '19 at 11:53
  • I'm looking at "If the contributor, then can license new contributions to an adaptation under 4.0 but original contributions remain under prior version unless express permission to upgrade is obtained." from that section, and the section below about mixed content. – mattdm Oct 5 '19 at 12:30
  • Yes, but SO is not the contributor. – GolezTrol Oct 5 '19 at 19:36
  • @GolezTrol I'm confused by your objection. The rights are held by the contributor, not Stack Exchange, so therefore this approach can be taken. – mattdm Oct 6 '19 at 4:40
  • Which approach? Upgrading the license? If contributors own the content, that approach can be taken by the contributors alone, which is the whole point of the ongoing discussion. – GolezTrol Oct 6 '19 at 7:11
  • @GolezTrol I think you're misunderstanding. SO is the publisher and the contributors own the rights. So we are exactly in the situation which that case describes. If the publisher owns the rights, the sentence "If the publisher, then can license all rights to an adaptation under 4.0." applies and everything is simple. – mattdm Oct 6 '19 at 19:43
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    I'm saying: SO has acted as if they own the rights, which they don't. But there's a pretty straightforward different approach to moving to 4.0 which they could take. – mattdm Oct 6 '19 at 19:45

I'm gonna make this a top level answer, because it's been brought up in multiple previous answers.

I believe they are using the CC license itself to grant them the ability to unilaterally move all content from 3.0 to 4.0. I found this Answer when I looked up "how to migrate from CC 3.0 to 4.0". It quotes section 4(b) as saying the following:

You may Distribute or Publicly Perform an Adaptation only under the terms of:
(i) this License;
(ii) a later version of this License with the same License Elements as this License;
(iii) a Creative Commons jurisdiction license (either this or a later license version) that contains the same License Elements as this License (e.g., Attribution-ShareAlike 3.0 US));
(iv) a Creative Commons Compatible License.

I am not a lawyer. However, subsections (ii), (iii), and (iv) all seem to indicate that the license for the content can be upgraded, and still be compatible with the original license.

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    Section 4(b) applies only to "Adaptations" (see 4(b)'s 1st 12 words). Please see the definitions of "Adaptation" and "Collection" in CC BY-SA 3.0. I don't see any way that what SE provides is not a "Collection". If it is a "Collection", then it is explicitly barred from being an "Adaptation" (this is stated in both the definition of "Adaptation" and "Collection"). Thus, section 4(b) does not apply to what SE provides. Note that an individual post which has been edited does become an "Adaptation", but SE provides a "Collection" of those. – Makyen Sep 16 '19 at 6:10
  • @Makyen I can easily argue it's an Adaptation. As you say, any edit makes it an Adaptation, rather than a Collection. Only if the content is shown verbatim can it be considered a Collection. And every single post made here is edited before it is shown. As such, it arguably fits the definition of an Adaptation, and not the definition of a Collection. Just because it is clearly a "collection" doesn't mean it fits the definition of a "Collection." They made that definition rather restrictive. – trlkly Sep 16 '19 at 16:42
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    I'm not a lawyer, but as I understand it, what this section effectively allows you to do is only to license your contributions to the Adaptation under a later CC license version. An Adaptation is legally a derivative work, and can only be distributed with the permission of the copyright holders of both the original work and the derivative. Such permission (a.k.a. a license) can, and usually does, come with restrictions, and if the licenses of the original work and the derivative have different restrictions, you must comply with both of them for the permission to be valid. […] – Ilmari Karonen Sep 16 '19 at 19:15
  • […] For example, if I release a work under CC-By, the license includes an explicit permission for you to make Adaptations of it and distribute them under any terms you want, as long as you (and everyone else redistributing the Adaptation or making further Adaptations of it) also abide by the terms of the original CC-By license (i.e. correctly attribute the original work to me). […] – Ilmari Karonen Sep 16 '19 at 19:16
  • […] CC-By-SA, meanwhile, adds the extra restriction (the "ShareAlike" clause) requiring you to also license your copyright to any Adaptations of my CC-By-SA works under the same license, or a later and/or localized version of it or a CC Compatible License. But that doesn't change the fact that such an Adaptation is still a derivative of the original CC-By-SA work, and may only be distributed in ways permitted by (the specific version of) the original license. So, basically, a CC-By-SA 4.0 Adaptation of a CC-By-SA 3.0 work may only be distributed in ways that comply with both licenses. – Ilmari Karonen Sep 16 '19 at 19:16
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    @trlkly I am the author of the opensource.SE answer you linked. That Q&A only discusses the case of an Adaptation. I also explained in the answer: “In this sense, the CC licenses have a compatibility mechanism but no way to do a license migration”. You are right that SO could make Adaptations of every post and then license that Adaptation under CC-BY-SA 4.0. But Adaptations must still be (creative) works. You can't create adaptations mechanically. Mere format-shifting, trivial edits, or similar transformations don't qualify as a creative work in the sense of typical copyright laws. – amon Sep 16 '19 at 19:54
  • @Makyen: A copy still is a work based on the work (in that very beginning of what an adaption is), the further ongoing of that pargraph goes into more details what an adaption further on would construe (incl. recast if copy is too generic for you what an adaption (with no change) still an adaption is even you don't want to see it so. What this is about is that the user of a work who is not the author gains rights as licensed per the original author. This includes creating his/her own verbatim copies. A collection comes with it's own rights (for the collection itselfs) which explain it's ment.. – hakre Sep 16 '19 at 23:54
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    @hakre: That would prove far too much, as then it would be trivial for anyone to relicense any CC work away to any other license they wanted. That's clearly not the case. – Nathan Tuggy Sep 17 '19 at 3:22
  • @Nathan: Not so sure I get what you write. There are specific restrictions to choice of license, they are named in the (3.0) license. One of the restrictions is to use a newer version of the license (and only with the same elements, e.g. CC-BY-SA here) for the CC-BY-SA 3.0 licensed work. I thought only the scenario to use 4.0 for 3.0 licensed works is on discussion. – hakre Sep 17 '19 at 11:09

Thanks to those who have waited patiently for us to provide clarity here. As this involves passing feedback to our legal counsel, answers can sometimes take time.

As mentioned in the announcement, we are unable to pursue dialogues that would put us (or our counsel) in the position of providing legal advice to you. However, we want to affirm: our counsel is and will continue to be involved and on-board with any steps we take to perform our role as stewards of our sites. Maintaining, updating, and enforcing our Terms Of Service is essential to fulfilling this role.

Another question that sticks out is, what prompted the change? Below is a list of bullets as to why we view this as an essential choice concerning the folks that will be responsible for the content for years to come:

  • More explicit rights to be disassociated. We’ve always honored requests for having a contribution disassociated from your account, whether it was an adaptation or not. Version 4.0 of the license gives you explicit rights to be disassociated from any verbatim copy of your contribution, not just an adaptation. This gives you more footing to deal with scraper sites as an individual if you find it necessary.

  • More rights + more global adaptation = better. There’s a lot of stuff that version 3.0 of the license almost did well, but due to ways certain wording could be interpreted, sometimes fell short. 4.0 is in no way a magic bullet to make the license 100% enforceable in every corner of the world, but it exceeds the efficacy of 3.0 substantially.

  • Better and simpler cure for infringement. Dealing with scraper sites is a time-consuming process, especially when international sites are the ones being scraped. There are also more proxies popping up on temporary domains to get around government censorship. 4.0 gives us better tools to more aggressively pursue bad actors, and more flexibility to work with folks that are responsive and want to comply. Additionally, rights are automatically reinstated if a site falls into compliance within a month of receiving notice which fits our process much better.

  • Clarity across the board. The license is much easier to read which also makes it much easier to translate (and, as necessary, transliterate). If that wasn’t enough, the license has already been ported to most major languages. Our international strategy is going to be an important theme in the years to come.

We feel well-positioned to meet the challenges of curating your contributions on a growing scale, and we’re learning as we go. We take the role very seriously and this was an important step we were very pleased to take.

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    On what basis did your attorneys determine that the retroactive change was allowed? – jhpratt Sep 27 '19 at 19:30
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    We're not asking for legal advice. We're asking a yes/no question that your lawyers have to be able to answer. If they can't, regardless of whether they're giving out legal advice, you're unable to defend your own change. If you can't defend your own change to users asking for clarification, how do you expect to defend it when (yes, when) someone decides to sue you? Personally, I have nothing against the license, but that doesn't automatically make it right to do, and that sure as hell doesn't hold up in court. – Zoe the 1337 Princess Sep 27 '19 at 19:58
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    I'm not a lawyer, so I can't really be sure I understand the details, but that is the same position most people affected by this change are in. To me the by far biggest issue here is that it is somewhat unclear to me whether SE is allowed to unilaterally change the license this way. And my interpretation of this is that if there is actually any legal doubt here, it puts everyone using the content under the new license in a rather awkward position, and might cause all kinds of havoc if the license change were declared invalid. – Mad Scientist Sep 27 '19 at 22:11
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    I would prefer the new CC license, and I have no issue with the relicensing myself. The one thing I really dislike here is having to think about licenses at all, I'm way out of my area of expertise, I'm in no position to get any real legal opinion on this, and I've seen some arguments that are plausible enough that I'm simply not sure how this will play out. This move as it has been done right now increases the uncertainty around the license state of SE content, and uncertainty is the last thing anyone needs in this area. – Mad Scientist Sep 27 '19 at 22:14
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    This does not address the concerns that I have raised. I'd like to know exactly what clause(s) in either CC-BY-SA 3.0 or the Terms of Service before 5 September grant the permission to change the license. My understanding and the official guidance from CC is that my permission is required to change the license and that permission was not granted in the pre-Sept 5 TOS nor in the CC-BY-SA 3.0 license. It's OK for the license of the Collective Work to be changed, but my individual contributions should be marked with the license originally granted until permission is granted for a change. – Thomas Owens Sep 28 '19 at 1:00
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    Also, in case you decide to ignore my comment because you don't think it's serious "thanks to arbitration": there's been a discussion on who can get out of it. Not to forget EU citizens, and people who opted out. The longer you decide to keep this game up, the more likely it is someone decides to sue you. I don't have all the info, but I have a feeling you don't have the budget capacity to handle that either. You have a chance here - don't waste it. – Zoe the 1337 Princess Sep 28 '19 at 9:04
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    I've revised my answer to explicitly walk through and quote the Terms of Service and the license that I granted for my contributions. I'd like these concerns to be addressed by SE. – Thomas Owens Sep 28 '19 at 10:41
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    Justifying the legality of your actions that, on the face of it, look like daylight robbery, does not constitute “legal advice”. – Emil Jeřábek Sep 29 '19 at 10:48
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    Downvoted because this does not address any concerns or questions raised. As is clearly explained in the meta help center : votes reflect the perceived usefulness: well-written, well-reasoned, well-researched posts tend to get more attention and more upvotes. I would suggest you take the time to read the the other discussions occurring, as this post is not at all helpful. People are not arguing the reasoning for using a 4.0 license, there are concerns about the retroactive, unilateral, non-consensual, forcing of it, which seems illegal – cegfault Sep 29 '19 at 12:04
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    Unfortunately this contribution doesn't answer the questions raised and I don't really understand the argument about legal counsel. An explanation on what legal basis a certain change was taken should be straightforward and not fall under legal counsel. Something like "This is not legal counsel, but this ... is why we think we can do that." So simple. No clarity yet, unfortunately. – Trilarion Sep 30 '19 at 8:30
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    I suspect you've misspelled "provide details on our behaviour because we know it's a breach of the CC license and anything we say here would undermine our position in a possible lawsuit" as "pursue dialogues that would put us (or our counsel) in the position of providing legal advice to you". Sorry, Tim, but it's incredibly hard to assume good faith on the part of SE on this one given the complete disregard for community feedback in this answer. – E.P. Sep 30 '19 at 20:04
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    This doesn't address any of the issues raised by community nor giving out proper reply here. why? – Vishwa Oct 1 '19 at 5:12
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    This reads like: "we can't tell you on what legal grounds we think this is OK because it actually very well might not be, but if we told you that we would outright admit to culpability, which our legal department obviously considers undesirable. Please sue us if you'd like to know more, as that's the only time we can actually go into this." The answer would be improved by being a less glaring legal void. – Jeroen Mostert Oct 1 '19 at 8:06
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    A complete non-answer to the questions raised would be just as well if not better served by... not posting an answer. I'm honestly confused how you think posting this could have painted SO in any better light than continued silence would have. – jmbpiano Oct 2 '19 at 18:41
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    There's now a GoFundMe campaign to take legal action against SE over this. Congratulations, your (the company's) inability to reply has gotten you two lawsuits – Zoe the 1337 Princess Nov 8 '19 at 10:10

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