The Steve Ditko Estate that is lead by the late comic book artist’s nephew has registered two notices of Copyright Termination against Marvel for Spider-Man and Doctor Strange, as reported by THR. Writer and penciler, Steve Ditko, was along with legendary comic book writer Stan Lee the co-creator of two of Marvel’s most famous and iconic superheroes, back in the 60s.

Doctor Strange’s first appearance was in Strange Tales #110 in 1963 and Spider-man’s first appearance was in Amazing Fantasy #15 in 1962. Both of these issues were signed by Stan Lee and Steve Ditko as co-creators. Now, a copyright law from 1976 has opened a window for the Steve Ditko Estate to regain rights to these fan-favorite characters. According to that law, creators of intellectual property and even heirs of those creators have a five-year window after fifty-six years to terminate the copyright. That means the window started in 2018 and ends in 2023, for the Copyright Termination for Spider-Man and another five-year window for Doctor Strange copyright termination from 2019 to 2024. This case can of course be dismissed by Marvel by simply claiming that these two superheroes were created under a “Work For Hire” contract. The exact terms of the contract between Steve Ditko and Marvel are left unclear.

A very similar case has already happened with the Siegel family and the copyright to DC Comics’ favorite son, Superman. Jerry Siegel’s family has successfully regained rights to the Superman copyright when it demanded its termination. An undisclosed monetary settlement and the line “By Special Arrangement with the Jerry Siegel Family” at the beginning of every Superman movie settled the affair.

A less successful arrangement was handled between Marvel and Jack Kirby’s family when they filed for 45 termination notices. They lost their case in multiple courts because Kirby’s work was considered work for hire. The Kirby family later stated that they had “amicably resolved their legal disputes” with Marvel. Most likely a monetary compensation was given out to the Kirby estate as The Eternals movie, originally one of Kirby’s creations, is coming out in movie theaters this December.