LOS ANGELES — Time Warner is no longer the sole proprietor of Superman.

A federal judge here on Wednesday ruled that the heirs of Jerome Siegel — who 70 years ago sold the rights to the action hero he created with Joseph Shuster to Detective Comics for $130 — were entitled to claim a share of the United States copyright to the character. The ruling left intact Time Warner’s international rights to the character, which it has long owned through its DC Comics unit.

And it reserved for trial questions over how much the company may owe the Siegel heirs for use of the character since 1999, when their ownership is deemed to have been restored. Also to be resolved is whether the heirs are entitled to payments directly from Time Warner’s film unit, Warner Brothers, which took in $200 million at the domestic box office with “Superman Returns” in 2006, or only from the DC unit’s Superman profits.

Still, the ruling threatened to complicate Warner’s plans to make more films featuring Superman, including another sequel and a planned movie based on the DC Comics’ “Justice League of America,” in which he joins Batman, Wonder Woman and other superheroes to battle evildoers.

If the ruling survives a Time Warner legal challenge, it may also open the door to a similar reversion of rights to the estate of Mr. Shuster in 2013. That would give heirs of the two creators control over use of their lucrative character until at least 2033 — and perhaps longer, if Congress once again extends copyright terms — according to Marc Toberoff, a lawyer who represents the Siegels and the Shuster estate.

“It would be very powerful,” said Mr. Toberoff, speaking by telephone on Friday. “After 2013, Time Warner couldn’t exploit any new Superman-derived works without a license from the Siegels and Shusters.”

Time Warner lawyers declined to discuss the decision, a spokesman said. A similar ruling in 2006 allowed the Siegels to recapture their rights in the Superboy character, without determining whether Superboy was, in fact, the basis for Warner Brothers’s “Smallville” television series. The decision was later challenged in a case that has yet to be resolved, said Mr. Toberoff, who represented the family in that action.

This week’s decision by Stephen G. Larson, a judge in the Federal District Court for the Central District of California, provided long-sought vindication to the wife and daughter of Mr. Siegel, who had bemoaned until his death in 1996 having parted so cheaply with rights to the lucrative hero.

“We were just stubborn,” Joanne Siegel, Mr. Siegel’s widow, said in a joint interview with her daughter, Laura Siegel Larson. “It was a dream of Jerry’s, and we just took up the task.”

The ruling specifically upheld the Siegels’ copyright in the Superman material published in Detective Comics’ Action Comics Vol. 1. The extent to which later iterations of the character are derived from that original was not determined by the judge.

In an unusually detailed narrative, the judge’s 72-page order described how Mr. Siegel and Mr. Shuster, as teenagers at Glenville High School in Cleveland, became friends and collaborators on their school newspaper in 1932. They worked together on a short story, “The Reign of the Superman,” in which their famous character first appeared not as hero, but villain.

By 1937, the pair were offering publishers comic strips in which the classic Superman elements — cape, logo and Clark Kent alter-ego — were already set. When Detective Comics bought 13 pages of work for its new Action Comics series the next year, the company sent Mr. Siegel a check for $130, and received in return a release from both creators granting the company rights to Superman “to have and hold forever,” the order noted.

In the late 1940s, a referee in a New York court upheld Detective Comics’ copyright, prompting Mr. Siegel and Mr. Shuster to drop their claim in exchange for $94,000. More than 30 years later, DC Comics (the successor to Detective Comics) gave the creators each a $20,000-per-year annuity that was later increased to $30,000. In 1997, however, Mrs. Siegel and her daughter served copyright termination notices under provisions of a 1976 law that permits heirs, under certain circumstances, to recover rights to creations.

Mr. Toberoff, their lawyer, has been something of a gadfly to Warner in the past. In the late 1990s, for example, he represented Gilbert Ralston, a television writer, in a legal battle over his rights in the CBS television series “The Wild Wild West,” which was the basis for a 1999 Warner Brothers film that starred Will Smith. The case, said Mr. Toberoff, was settled.

Compensation to the Siegels would be limited to any work created after their 1999 termination date. Income from the 1978 “Superman” film, or the three sequels that followed in the 1980s, are not at issue. But a “Superman Returns” sequel being planned with the filmmaker Bryan Singer (who has also directed “The Usual Suspects” and “X-Men”) might require payments to the Siegels, should they prevail in a demand that the studio’s income, not just that of the comics unit, be subject to a court-ordered accounting.

Mrs. Siegel and Ms. Larson said it was too soon to make future plans for the Superman character. But they were inclined to relish this moment.

“I have lived in the shadow of this my whole life,” Ms. Larson said. “I am so happy now, I just can’t explain it.”