You may have seen the New York Times article about a judge's ruling in favor of the heirs of Jerry Siegel in regard to sharing the rights for the original Superman story.
Situations like this convince me more than ever that our copyright laws are so screwed up as to be nearly hopeless.
Jerry Siegel and Joe Schuster entered into a willing arrangement to sell the rights to Superman to another company. They took the money, they closed the deal... and under the law of the time, that settled the matter. Then, years later, the law was rewritten and suddenly heirs who had nothing to do with the creation of Superman find themselves allowed to stake a claim to the same rights that the creators sold off.
Copyrights are assets. If I sell another asset, like my copy of Action Comics #1 (no, I don't really have one) to someone else, my heirs don't have the right to force that person to give it back to them after I die. For some reason, though, the copyright law has been restructured to give this strange boomerang ability to copyrights, even though no other form of asset works the same way.
I am all in favor of copyright protections for creators... but that protection should also protect the rights of those who pay out money to purchase those copyrights. This current law simply screws over those who made the process of creation profitable to begin with.