Every bit of research I have done on the public domain status of the pre DC Charlton characters such as Captain Atom and Blue Beetle has yielded the response "probably not."
And while I agree, I'm curious about the why and how. I'm no expert on copyright law and mind you, I have no plans whatsoever to make a comic or story featuring DC characters, but I found this quote interesting:
https://en-academic.com/dic.nsf/enwiki/839503
So if this is true-- can it seriously be assumed that someone could use DG BB and the original Allen Adam in their story without any legal response from DC? How exactly does this work and how can one find this out definitively? I understand that "it's DC, you don't want to do it either way" but I'm interested in discussing it regardless.
There are several "fan made" publications out there of old Charlton, Fawcett, and Quality comics, including some old Captain Marvel stories! And I even read somewhere that the original version of Captain Marvel
is public domain, but he can't be called Captain Marvel or Billy Batson or look like him, and can't be on the cover, and his character has to be based on the character in the specific issues that are public domain and not anything else. So if it's true, then CM jr would also be PD.
Does anyone (with or without knowledge of copyright law) have any insight into this mystery?