R2 sounds like the right question. Thanks.

Once again, it's silly to talk about this issue going to court. Wikimedia contributors are not taking other Wikimedia contributors to court over internal disagreements on how the CC-By-SA license should apply. But we're weakening the legitimacy of Wikimedia licenses by not resolving this.

My previous comment probably crossed a line. I'm sorry.

[...] without any reference to the originating author. So if that is the case, Wikipedia has already never been compliant with that license.

@Denny Nobody's copyright is going to be invalidated by your personal beliefs.

the fact that 'London' is called 'Londres' in Frech is rather un-creative

If you really wish for your data to be under CC0, why would you have any preferences at all over what happens to it? CC0 is the license where your wishes don't matter. It's as close to public domain as possible.

The point is not whether Wikipedia (or another project) can "claim infringement" against Wikidata. Nobody would want to be in the absurd and expensive situation of taking the contributors of another project to court. The point is that Wikidata should just not infringe anyway.

I must amend my previous statement; I thought Wikipedia categories were all represented on Wikidata, but it appears they may not be. Maybe I don't know how to use Wikidata, or maybe this is something that could be possible if Wikidata were CC-By-SA.

Wikidata has copied the entire ontology of Wikipedia categories.

Tgr: The situation of having the copyright on a project held by a large number of different individuals is not unique, and it does not at all make the copyright invalid like the "monkey selfie". This is the way that most open-source software projects work.

I agree that Wikidata has been making a big mistake here.