If you thought the nearly decade-long legal battle for the rights to the Man of Steel had come to an end last month, think again: On Thursday, the attorney for the Joe Shuster estate asked the 9th Circuit Court of Appeals to overturn an October ruling that the family was prevented from reclaiming the artist's stake in Superman by a 20-year-old agreement with DC Comics.

At issue is a 1992 deal in which the estate relinquished all claims to the property in exchange for “more than $600,000 and other benefits,” which included paying Shuster’s debts following his death earlier that year and providing his sister Jean Peavy and brother Frank Shuster with a $25,000 annual pension. On Oct. 17, U.S. District Judge Otis D. Wright found that the agreement invalidated a copyright-termination notice filed in 2003 by Shuster's nephew Mark Peary. Less than three months later, the 9th Circuit overturned a 2008 decision granting the heirs of Jerry Siegel the writer's 50-percent share of the copyright to the first Superman story in Action Comics #1, effectively granting DC full ownership of the character.

But Courthouse News Service reports that on Thursday, the Shuster estate's attorney Marc Toberoff insisted that Wright "committed clear error" by finding that the one-page pension agreement precluded the family from exercising its termination rights under U.S. copyright law. What's more, he asserted, Peavy and Frank Shuster had no termination rights to exercise in 1992 because Shuster's stake in Superman had been assigned to DC in 1938, and the publisher still owned the rights at the time of the pension agreement.

Before the 1998 Copyright Extension Act, termination rights were granted only to an author's spouse, children or grandchildren, Toberoff said, offering, "Joe Shuster was never married and had no children, so no one held the termination right in 1992."

He also focused on the wording of the 1992 pension agreement, which didn't revoke Joe Shuster's previous grants of copyright to the publisher. "It contains no language of rescission, revocation, cancellation, replacement, or any of its synonyms," the attorney said. "And given the tremendous value of the Superman franchise, if that was the intent of DC's lawyers who drafted this simple 1992 pension agreement they would have said so in plain English."

If that argument sounds familiar, it's because Toberoff had made a similar one in September before Wright, who initially seemed swayed by the contention that DC never intended the “ambiguous” document to transfer ownership of copyright to “a billion-dollar property.”

DC's attorney Daniel Petrocelli countered that the 2003 notice was invalid because the Copyright Extension Act only permits heirs to terminate grants of copyright made before 1978: Because Jean Peavy signed the 1992 agreement, there were no rights to be terminated in 2003.

"Whether or not you have a termination right doesn't depend on anybody's intention - whether you're intending to preserve something, or intending to extinguish something," he told the three-judge panel. "It depends on the date of the grant, and the legal relationship between the people who are doing this."