We’d like to provide you with an update to our transition to version 4.0 of the CC BY-SA license. We realize that this is something that you care deeply about, and that our response to your concerns is long overdue. We’d like to thank all of you for your patience while we worked on a plan forward that would address your concerns.
The change to CC BY-SA 4.0 occurred on 2018-05-02 (May 2, 2018) as part of our ToS update. It was updated as part of a process that was not led by the community team and there was an internal disconnect at the time of the release.
Our move forward plan is to switch to a licensing scheme where:
Content contributed before 2018-05-02 (UTC) is distributed under the terms of CC BY-SA 3.0
Content contributed on or after 2018-05-02 (UTC) is distributed under the terms of CC BY-SA 4.0
This will correct any inconsistencies with the prevailing and advertised licenses.
We’re working on ways we can make licensing details easily discoverable on post timelines as well as API calls, and we’ll share ideas as soon as they’re coherent enough to communicate. We anticipate having the new license labeling scheme ready by April 2020 and look forward to posting updates on this as we have them.
We are still investigating the question of substantial edits to content licensed under CC BY-SA 3.0 now that we’ve switched to version 4.0. For the time being, pending final clarification on this, content will be listed with a license based on its creation date. This would mean if a question or answer was created under CC BY-SA 3.0, revisions to it made today would also be released under CC BY-SA 3.0, not 4.0.
Your feedback made it clear that your concerns were mostly about the way the change was handled, and not so much about any specific version of the CC BY-SA license. We’re looking at ways that we, as the custodians of your contributions, can make decisions about the license quickly, in a transparent and informative way, to protect your content as the world’s legal landscape changes. Our network of sites has grown to the point where it’s impossible for us to obtain permission from all contributors if a further update to the license becomes necessary and we may find ourselves in a position where we must act quickly. If such a situation arises, and we need to update to the most recent version of CC BY-SA, we will make sure to let you know. It’s our responsibility to ensure that your contributions remain open and accessible to the world, in the same giving spirit that you provided them.
Thank you, again, for your patience. We’re happy to hear any feedback you might have. Please understand that we’re unable to provide any answers to questions about licensing that could possibly be interpreted as us giving legal advice.
Update from Yaakov: Please see Creative Commons Licensing UI and Data Updates for details on UI updates related to this issue, as well as answers to all open questions left over from this post.