This seems like a silly question to me, and only a hypothetical at the moment, but I needed to ask! It's specific to United States copyright law, just to be clear.
Let's say an app author builds a solution that's only to be used by a small, internal group of users. Is it legally possible for the app to have a EULA upon entering the experience that requires any viewer to surrender the rights they may have to any of the content inside the app, if that content is prospectively owned by the user themselves?
More specifically, I'll pose a scenario: let's say we're talking about a free app for a private audience, which includes training for the Praxis exam, but potentially also includes example questions taken from official Praxis training materials. Is it possible to have the user agree to a EULA that states they will not file a copyright claim around any content they may discover they actually own rights to, when using the app?
If this is indeed legally possible, this seems like a very sticky situation that could open a can of worms: how do you maintain copyright status against media that was stolen, if you can't verify ownership of that media without agreeing to a EULA that nullifies your claim to the rights of said media?