Imagine that some person X is running a website where they provide access to some creative work and claim that it is in the public domain, or under a permissive copyright license.
Imagine that Y retrieves the work and makes use of it in a way which is permitted by the license and would not be permitted otherwise. For instance, Y redistributes the work, sells it, translates it, etc.
Now, imagine that the work is actually not at all under this permissive license, and X's claim to that effect was wrong. Now, the actual copyright owner on the work, Z, notices Y's illegal use of their work, and sues them for copyright violation.
- Can Y defend themselves by pointing out that they thought their use was permitted because of X's claim? Or are they fully responsible for their use of the work?
- Could Y attack X for their false claim about the license of the work? If yes, to what extent would X be responsible?
- Would it make a difference whether X was acting in good faith or not? E.g., maybe X really thought the work was under that license and were wrong, for instance because they had copied it from some other source with a wrong license claim. Or maybe X had not really made any effort to check the origin of the work, and they should have known that the license was not as indicated.
- In the shoes of X, is there a way to distribute some creative work under a free license without promising that you have checked its copyright status carefully? E.g., say that you are allowing its use under a free license as far as you are concerned, but you don't promise that other parties like Z may not have a claim to it?
This last question is motivated by situations where a creator X takes a copyrighted work by Z, makes some derivative of it with an unclear copyright status (e.g., a mashup, parody, etc.), and wants to distribute it and say "I'd like to put it under a free license but I don't promise that Z doesn't have a valid copyright claim against reuse of the work." This is important because in many cases Z will leave X alone (e.g., because they are distributing the derivative work noncommercially) but could pursue some third-party Y if they started selling the derivative work by X.