Seeking to end nearly a decade of litigation, DC Comics has asked for summary judgment in lawsuits brought by the heirs of Jerry Siegel regarding the copyrights to Superman and Superboy.

In a motion filed Thursday in federal court, and first reported by Law360, the publisher's attorneys assert the Jan. 10 ruling by the Ninth Circuit Court of Appeals that effectively affirmed DC's ownership of the Man of Steel bars Siegel's daughter Laura Siegel Larson from moving forward with any claims.

That decision overturned a 2008 ruling that permitted Siegel's family to recapture his portion of the copyright to the first Superman story in Action Comics #1 under a provision of the 1976 Copyright Act, which seemingly cleared a path for the estate of his collaborator Joe Shuster to do the same this year. That would have given the family of ownership of many 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), while leaving DC with such later additions as Lex Luthor, kryptonite and Jimmy Olsen -- not to mention the all-important trademarks.

However, that possibility was relatively short-lived: In October 2012, a federal judge found the Shuster estate's 2003 copyright-termination notice 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.

The Jan. 10 ruling against the Siegel heirs also came down to an earlier agreement, as the Ninth Circuit found that Larson had accepted a 2001 offer from DC that would have permitted the publisher to retain all rights to Superman (as well as Superboy and The Spectre) in exchange for $3 million in cash and contingent compensation worth tens of millions. Larson insisted she never formally accepted the offer, freeing her and her late mother Joanne Siegel to pursue copyright termination. But the appeals court sided with DC, which argued the family had agreed to the settlement and only withdrew from the settlement after attorney Marc Toberoff entered the picture, falsely asserting he had a $15 million offer for the rights from a billionaire investor.

“As the Ninth Circuit noted, it is indeed the case that a ‘judgment in DC’s favor on its settlement counterclaim renders moot all of the other questions in this lawsuit,’” DC stated in the motion filed Thursday. “Her four claims in the Superman case all hinge on the validity of her termination notice and her continued ownership of the allegedly recaptured Superman copyrights. Larson traded any rights she had in Superman to DC, as part of the Oct. 19, 2001, agreement.”

DC has asked for a hearing before U.S. District Judge Otis D. Wright on March 11, the same day he will consider a motion to dismiss the publisher's copyright-interference claims against Toberoff.