The case is Golan v. Holder (originally filed when Gonzalez was Attorney General), and challenged the provision of the URAA that restored copyright to out of copyright works, and rendered derivative works that had been made when there was no copyright illegal, and now a Federal District Court has ruled it an unconstitutional violation of the first amendment, after a remand from the appeals court (PDF of opinion at link).
This is the first time ever that, “a court has held any part of the Copyright Act violates the First Amendment and the first time any court has placed specific constitutional limits on the government’s ability to erode the public domain,” so it is very significant.
This differs from Eldred, in which the Supreme Court allowed copyright extension, in that the speech of the plaintiffs was already legally created, and so the change was an infringement on their legally created speech (derivative works of then public domain items).
It is my understanding, that this applies only to legally created derivative works, and one would assume, newly created derivatives of those derivatives, but not new derivatives of these works, but I’m an engineer, not a lawyer, dammit!*
In either case, this is a recognition that IP law is a restriction of the rights of the rest of society, and as such there needs to be a showing a serious state interest in order to override that, and this is IMHO, a major step forward.
*I LOVE IT when I get to go all Doctor McCoy!!!