Okay, I have a problem. To make it short. I’ve helped so much with a Github repository that it could be said to be as good as my repo because of the amount of code I distributed (It’s like 99,5%). But now I want to make my own repository with this code for private reasons. But now the owner of the repo threatens to sue me. The license was CC0 at the time but it has now been switched to GPL-3.0. Would it be allowed to use the code that was before the license change?
I am not a laywer. This is not legal advice. If you need real legal advice, contact a real lawyer.
Keeping the disclaimer above strictly in mind, as this probably isn’t a good question to ask on an internet forum, I’d say yes, you can use the code how it was before the license switched over to GPL-3.0.
As for your claim that if you wrote most of the code you might as well “claim” the copyright, I don’t really think that is how copyright law actually works. Especially if those contributions were made under the CC0 license which waives copyright. But again, I’m not a lawyer.
You can also check out this site from GitHub with more information: