Originally Posted by
Jim Purcell
I'm not a IP lawyer, but as I understand it certain copyrights concerning Capt. Marvel (and Superman actually) have fallen into the public domain. So technically, yes you can totally use those copyrighted works as a base to write your own Capt. Marvel or Superman stories.
BUT, there are some significant catches. Its those Copyrights and ONLY those copyrights. And those early stories tend to lack the most iconic aspects of those characters. In Superman's case (which I know the most about), he only jumps. Doesn't fly. No X-ray Vision, no Heat Vision. He works at the Daily Star, not the Daily Planet. No Jimmy Olsen either (introduced in the Radio Show you see). Etc... etc... You can NOT infringe on the Copyrights DC/Warner still control, which is tricky due to how much of that canon is so entwined with the iconic Superman character.
And that's not even getting into the fact that DC owns the trademarks on all the character likenesses (Glasses + Curly Q Haircut are locked down I believe), names, logos (Chest Lighting Bolt, S Shield, etc...), and supporting cast likenesses. So it becomes even more of a challenge to incorporate these public domain copyrights into something new. Because you can't promote the usage of the characters at all. Or have to change them so much as to be unrecognizable.