Before you can reclaim a copyright, you have to prove you owned it in the first place, and that's not always a simple matter. Until very recently, comics freelancers routinely worked under Marvel and DC's work-for-hire rules, which meant that the copyright in any characters they created automatically belonged to the company signing their cheques. If JK Rowling had created Harry Potter under these arrangements, her publisher would have owned the character outright, been free to assign him to whatever other writer it chose and could have sold the movie rights without giving Rowling a penny.
In law, Potter's author would have been the company publishing his books, not any individual writer, and only that company would have any copyright claim. That's the first hurdle which any comics copyright lawsuit has to clear, and doing so means establishing that the character in question was created outside the work-for-hire system.
The Siegels achieved this by proving that the Superman material in Action Comics #1 - plus a few pages of his subsequent appearances - was already complete before DC even saw it. Siegel and Shuster had originally hoped to sell Superman as a syndicated newspaper strip, and all that was required to convert their finished sample strips into his first comic book was rearranging their panels into a new page shape. Satisfying the definition of work-for-hire would have meant DC showing the work had been completed at the publisher's instance and expense - which clearly wasn't the case here.
The resulting story filled 13 pages of Action Comics #1, which also featured Superman as its cover star. DC paid Siegel and Shuster $130 for the work, in return for which the two men signed a contract giving “exclusive rights to the characters and story, continuity and title of the strip contained therein to you and your assigns to have and hold forever and to be your exclusive property. [...] The intent hereof is to give you exclusive right to use and acknowledge that you own said characters or story and the use thereof exclusively.” (9)
To be fair to DC, no-one knew whether Superman would sell or not back in 1938, and if the book had tanked I don't suppose Siegel and Shuster would have rushed to return their fee. Even in 1938, though, $130 wasn't a lot of money - it would be worth about $2,000 today - and Siegel started arguing for a better deal almost immediately. He and Shuster were still writing and drawing Superman for DC, as well as a handful of other strips, and he asked Liebowitz to raise the shared page rate they now received from $10 to $15.
No dice. “You must bear in mind, Jerry, that when we started Action Comics, we agreed to give you $10 a page, which is $4 a page more than anyone else is getting for any features in any of our four books,” Liebowitz writes in a letter of September 1938. “In addition, we're paying you $9 and $10 a page for the other four features you are drawing for us - again, $3 and $4 a page more than we are paying any other artists. Where you get the idea that anyone is receiving $15 a page, I'd like to know.”
Later in the same letter, Liebowitz continues: “Is it possible that, because we treated you like a human being, you suddenly got a swelled head? [...] Don't get the idea that everyone in New York is a 'gyp' and a highbinder, and because you are treated as a gentleman and an equal not only by ourselves but by Mr Gaines and the McClure people, that we are seeking to take advantage of you.” (10)
Siegel and Shuster first sued DC in 1947, arguing their original contract amounted to an unfair deal. They lost that part of the case, but had more luck with their contention that DC had acted illegally by publishing a Superboy book without troubling to buy the character's rights from Jerry Siegel first.
Siegel had first pitched the idea of a Superboy comic to DC as early as November 1938, saying it would feature the adventures of Superman when he was a boy, but the company rejected his idea. The following year saw the debut of both Superman's newspaper strip and a comic under his own name, and Siegel thought this said enough about the character's popularity to repeat his Superboy pitch in 1940. DC turned it down again.
A Saturday Evening Post story reported the pair's gross earnings that year at $75,000, about $16,000 of which went in staff salaries and overheads at the Cleveland studio they'd now set up. In the same year, it added, Superman's main monthly comic was grossing $950,000, the syndicated newspaper strip pulling in another $100,000 for DC and the radio show generating total annual income of $75,000. Soon, Superman was also starring in a series of 17 Max Fleischer animated cartoons and a prose novel too. At its peak, Siegel and Shuster's newspaper strip appeared in over 200 papers, with a combined circulation of 25 million. (11)
Still Liebowitz took a hard line whenever the two men complained about their pay. “Forget about book rights, movie rights and all other dreams,” he wrote to Siegel in January 1940. “We'll take care of things in the proper manner.”
One bone of contention was the radio show, which didn't involve Siegel and Shuster directly, but which Siegel had hoped would employ him as a consultant. When this didn't happen, he complained to DC. The company responded by sending him and Shuster a shared cheque for $500, but made it clear this was purely an ex gratia payment. “They said 'Just to show you we're not forgetting you boys, we're giving you a $500 bonus,” Joe's cousin Frank Shuster later recalled. “So that's what they got. That was it.” (11)