Currently there's a big controversy over SE changing the licensing from CC 3.0 to CC 4.0. Regardless of whether this change was legally solid or not, could someone provide a specific example of how this licensing ambiguity affects our ability to copy, share and reuse content published on SE in the past?

Let's say I find an interesting piece of code on Stack Overflow from 2017 and add it to my open source project with attribution, citing CC BY SA. Could the author of this piece of code claim a copyright violation somehow, given the licensing ambiguity? The way I see it - the code is licensed under either 3.0 or 4.0 and the difference between the licenses is so small in practice that knowing the exact version shouldn't matter. Whoever wrote the code couldn't suddenly claim that the licensing change completely revoked their original CC attribution, making it impossible for others to reuse their content.

Note that I'm not interested in whether or not the licensing change was legal/moral/appropriate/cool. I'm merely asking about how it affects my rights to reuse content posted on SE.

Relevant posts on other sites:

  1. How do you write an attribution if there's ambiguity over which version of Creative Commons applies?
  2. In which context would the difference in licensing rules between CC BY-SA 3.0 and CC BY-SA 4.0 actually matter?
  3. Is there an official guideline from Creative Commons on how a CC-BY-SA 3.0 website could "upgrade" to CC-BY-SA 4.0?

The aspect in which the uncertainty about the license change affects me most in terms of practical considerations is that the usage of the content outside of Stack Overflow is suddenly subject to complicated considerations.

If I don't know if the content is really CC-BY-SA-3.0 or 4.0, I cannot mix with other CC-BY-SA-3.0 content (because the content could be 4.0) and still claim it's 3.0 (because CC-BY-SA is not backwards compatible). I don't even know what license I should write below this content. ("Hey, this is some content that is either under CC-BY-SA-3.0 or 4.0."). Before I was in safe legal territory, now suddenly I'm not even sure what the license is at all. And people who then want to use my mixed content then will even be more unsure about the license. That's really bad and will surely impede innovation.

For me this is a huge practical hindrance. For Stack Overflow Inc. it may not matter that much because they can use the content for their purpose anyway (independent of 3.0 or 4.0) but for all other thinkable uses of the content it is essential to determine the license beyond doubt (because CC-BY-SA-3.0 is not 4.0). Apart from the differences in the license itself, the most practical problem is indeed the uncertainty about it. And the company has done zero to help bringing certainty. I know it because I have asked them for clarification multiple times and never got any answer. That's why I'm a bit unsatisfied with them.

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    In almost all cases, you can know the license. If it was posted before September 5, 2019 and hasn't been edited since then, it is under CC-BY-SA 3.0 (Creative Commons licenses can't be revoked) and may be under CC-BY-SA 4.0. If it was posted on or after September 5, 2019, it is under CC-BY-SA 4.0 and is not under CC-BY-SA 3.0. If it was posted before the changeover and edited after, it's almost certainly available under CC-BY-SA 4.0, since editing probably counts as creating an "adaptation" for the purposes of the license, which permits upgrading from 3.0 to 4.0. – Mark Nov 8 '19 at 20:24
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    @Mark Is there a way to see the license for each question or answer? – endolith Nov 8 '19 at 21:16
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    @Mark, that's interesting; does that mean that anyone who wants to use a currently 3.0-only post under the 4.0 licence merely needs to edit the post (minorly reword some stuff, for example), and it will automatically become 4.0? – Nate S. Nov 8 '19 at 21:52
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    @Mark Another slight wrinkle: any post made before April 8, 2011 is actually licensed under CC BY-SA 2.5, not 3.0. – Sonic the Anonymous Hedgehog Nov 9 '19 at 0:31

There are two other changes that are relevant:

  • If you violate the terms of the license, with version 3.0 your rights to use the content are immediately revoked, whereas with 4.0, you're given a 30-day grace period to correct any violation.

  • While you can use 3.0 content in a 4.0 work, you generally can't use 4.0 content in an exclusively 3.0 work. For example, code snippets published after the license change on Stack Overflow can't be posted to Wikipedia, an exclusively 3.0 work. (As far as I can best tell.)

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    can't be posted to Wikipedia. [en.wikipedia.org/wiki/Template:Cc-by-sa-4.0](License template). This template is used on approximately 11,000 pages. Someone should probably tell them 😓 – Pace Nov 7 '19 at 23:19
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    @Pace "This template should only be used on file pages. The text of Wikipedia is a 3.0 work, while other things are licensed under Wikimedia Foundation's terms of use under which the 4.0 license is compatible. – Sonic the Anonymous Hedgehog Nov 7 '19 at 23:23
  • But you can always quote (a short section) regardless of license. – curiousdannii Nov 8 '19 at 4:05
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    @curiousdannii Yes, that falls under "fair use" as defined in U.S. copyright law, and applies to all copyrighted works. – Sonic the Anonymous Hedgehog Nov 8 '19 at 4:09
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    That's of course only true if you are in the US. I am not and there is no "fair use" where I live. – Josef says Reinstate Monica Nov 8 '19 at 11:38

In your specific scenario of incorporating code into your project, the difference between 3.0 and 4.0 is irrelevant. Section 4b of the 3.0 license has the following clause:

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...

By incorporating the code into your project, you are unambiguously creating an "adaptation" as defined in section 1 of the license, and are free to use the code under either CC-BY-SA 3.0 or CC-BY-SA 4.0 (or any later version of CC-BY-SA).*

The Creative Commons website has a page on the differences between license versions. In general, as a re-user:

  • You could assert database rights over the content under 3.0, but can't under 4.0.
  • 4.0 explicitly grants permission to crack any DRM applied to the content; under 3.0, this was ambiguous.
  • If you're violating the terms of the license, you've got a 30-day grace period to fix the violation; under 3.0, the license is terminated immediately.
  • Under 3.0, the author can assert moral rights to a greater extent than under 4.0.
  • 4.0 grants slightly more flexibility in how you comply with the attribution and license-notification provisions, but also changes what elements must be included for proper attribution.

For most re-users, it's the attribution changes that are most likely to cause problems. It's possible to simultaneously be in compliance with 3.0 and 4.0, but it requires being careful about what you're doing.

*Note: you'd need to license the entire project under the license if you do this, and Creative Commons does not recommend using CC licenses other than CC-0 for software.

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    Note that if you do that, you have to license your entire project as CC-BY-SA. – OrangeDog Nov 8 '19 at 10:38

The difference wouldn't matter much. What matters is that the whole content on Stack Exchange has no valid license and you are not allowed to use it at all (except content completely created after the illegal license change).

There is at least one user here who thankfully tries to get clarity about the license change by suing Stack Exchange if needed. I will donate to their GoFundMe and if you want to know if you are allowed to use any Stack Exchange content at all without breaking the law you should too!

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    What about the data dumps containing the old content? Since they're still available, isn't all SE content from the past licensed as 3.0 in perpetuity? – JonathanReez Nov 8 '19 at 15:10
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    @JonathanReezSupportsMonica The original license was revoked the second they violated it. – jhpratt GOFUNDME RELICENSING Nov 8 '19 at 18:41
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    @jhpratt if I download a data dump from SE, how can any actions taken by SE later on revoke said license? Same applies for copies of posts hosted on archive.org - they're licensed under CC-BY-SA no matter what, aren't they? – JonathanReez Nov 8 '19 at 18:42
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    @JonathanReezSupportsMonica To be clear, Stack Exchange loses the right to use the content under CC. This also means they can no longer distribute it under those terms. The end user presumably has nothing to worry about. – jhpratt GOFUNDME RELICENSING Nov 8 '19 at 18:44
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    Josef - IMO, you'd need a lot more than $1000 to sue SE over this. $30k was estimated by Monica's lawyer and that's a much simpler defamation case. Here we're talking about complex licensing issues with few precedents. $100k would be a realistic starting figure. – JonathanReez Nov 8 '19 at 18:47
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    @JonathanReezSupportsMonica, Monica is willing to accept a settlement other than a monetary payout, and in fact would prefer such a settlement, so the lawyer needs to be paid up-front. A copyright-infringement suit is likely to involve a monetary payout, in which case the lawyer can expect to be paid mostly from the settlement funds. – Mark Nov 8 '19 at 21:30

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