Even as Cleveland's mayor proclaimed April 18 "Superman Day" to celebrate the 75th anniversary of the release of Action Comics #1, a federal judge effectively brought to an end the lengthy legal battle for the rights to the Man of Steel.

Deadline reports that on Thursday, U.S. District Judge Otis Wright granted summary judgment to DC Comics, declaring that a 2001 agreement with the heirs of Superman co-creator Jerry Siegel included the rights to Superboy and advertisements for Action Comics #1. Those two issues had been left unresolved in a January decision by the Ninth Circuit Court of Appeals overturning a 2008 ruling that the family had successfully reclaimed a portion of Siegel's copyright to the first Superman story under a provision of the 1976 Copyright Act.

Immediately following the successful debut of Superman in 1938, the writer had pitched DC the idea of a series following "the exploits of Superman as a young man.” The publisher twice rejected the proposal, but in 1943, while Siegel was stationed overseas in the Army, it released a five-page story introducing Superboy, without the writer's consent. Four years later, Siegel and artist Joe Shuster filed two lawsuits against the publisher, one to void their Superman agreement and the other for the rights to Superboy; they ended up agreeing to drop all claims in exchange for $94,000. However, that was merely the beginning of the decades-long dispute.

In the 2008 ruling, the judge determined the Siegels' 1997 copyright termination didn't incorporate Superboy and the Action Comics preview ads, but on Thursday Wright wrote "they undoubtedly intended" for those works to be included, and used the potential termination of those rights as leverage to negotiate the 2001 settlement. Under that agreement, the Siegels relinquished all claims to Superman and Superboy (as well as The Spectre) in exchange for "a $2 million advance, a $1 million non-recoupable signing bonus, forgiveness of a previous $250,000 advance, a guarantee of $500,000 per year for 10 years, a 6% royalty of gross revenues, and various other royalties." They were also to receive medical and dental insurance.

While the Siegels had argued they never accepted that deal, the Ninth Circuit determined in January that they had, therefore preventing them from reclaiming a portion of the copyright to Action Comics #1. The family has since changed strategy, arguing that if there was a contract with DC, then the publisher has failed to perform. (That explains the recent addition of the line "By Special Arrangement with the Jerry Siegel Family" to the credits of any DC title featuring Superman, a stipulation of the 2001 agreement.) Wright reiterated his earlier assertion that any breach-of-contract claims will have to be dealt with in state court.

Barring appeal, that contractual matter would appear to be the only dangling thread in the long, bitter fight for the rights to Superman.

The 2008 decision appeared, at least at the time, to pave the way for the Shuster estate to reclaim his portion of this this year, giving the two families ownership of the Man of Steel’s defining elements, including his origin, his secret identity, Lois Lane and certain aspects of his costume and powers (super-strength and super-speed). But in October 2012, a judge found that a copyright-termination filed in 2003 by Shuster's nephew Mark Peary was invalidated by a 20-year-old agreement with DC in which the late artist’s sister Jean Peavy relinquished all claims to Superman in exchange “more than $600,000 and other benefits,” including payment of Shuster’s debts following his death earlier that year and a $25,000 annual pension for Peavy.