The heirs of Superman writer and creator Jerry Siegel were awarded the copyright to Action Comics #1. Now what all this means legally is for better minds than mine to figure out. There's still a lot to be figured out, it seems that they only have the rights to what appeared in that first issue, so where does that leave characters like Lex Luthor and others that came in later issues? Where does that leave DC as far as publishing Superman comics? Lots of issues to figure out.
What to me is almost shameful is the reaction of a lot of fandom to this decision. Instead of celebrating the win of one of the creators of one of the most famous icons in the world these fans are worried what this might mean to their daily fix of Superman. They are calling the Siegels greedy for wanting what should be rightfully theirs. People are claiming it would be all right if it was Jerry Siegel winning the award, but since he's dead that would be kind of hard. Why shouldn't his family share in some of the riches that Jerry's creation brings in.
A contract was signed is what is used to side with Warners. They didn't have to sign the contract, they wanted the quick money. Well, it wasn't that much money, even for the time. What they wanted was to get their character in print. At that time no one had any idea what a comic book character could achieve. If there were any ideas they probably would have imagined things alongside what comic strip creators achieved. Even though comic strip artists sold their rights they could end up making a lot of money and work on the strips they created for years.
If anyone thinks it is fair for two naive, young creators signing away their life's opus without knowing what they are doing is missing the point of characters like Superman, who represent the good guy looking out for the little guy.