WASHINGTON – Anna Nicole Smith, the former Playboy Playmate and widow of a Texas oil billionaire, won a unanimous ruling from the Supreme Court yesterday that clears the way for her to claim as much as $500 million from her late husband’s estate.

But the decision does not finally resolve the 11-year old legal dispute, which has bounced back and forth between the state courts of Texas and the federal courts in California.

The court battle has been fought over who lied and schemed to get shares of the estate of J. Howard Marshall: his son or his widow. Marshall was 89 years old and worth an estimated $1.6 billion in 1994 when he married the 26-year-old model. He died a year later, and the fight was on.

A Texas court backed the oilman’s son, E. Pierce Marshall, but a federal bankruptcy judge backed Ms. Smith.

In a victory for the widow, the Supreme Court tossed out a Decision saying federal judges had no authority to decide a lawsuit she brought against her stepson. She claimed he schemed and forged documents to deprive her of a huge gift her husband promised her before his death.

Despite his loss yesterday, Pierce Marshall vowed to fight on. “I will fight to clear my name in California federal court. That is a promise [she] and her lawyers can take to the bank,” he said.

So far, both sides have taken plenty of money to their lawyers, not to the bank. Experts in bankruptcy law agreed the battle will drag on.

“There is a long way to go between here and her ability to collect any money judgment against Pierce Marshall,” a Washington lawyer who filed a court brief on behalf of experts in bankruptcy, Craig Goldblatt, said.

That is because the Supreme Court did not decide whether the Texas court or the federal bankruptcy court in California handed down the first decision. Usually, when judges are dueling over who gets to decide an issue, the first ruling is honored in the end.

After the death of Marshall, his will was probated in a Texas court, which agreed he intended to leave his estate entirely to E. Pierce Marshall.

Meanwhile, in a separate suit brought in a bankruptcy court in Los Angeles, Ms. Smith alleged the billionaire’s son had – before her husband’s death – schemed to deny her what she had been promised. She had filed for bankruptcy for unrelated reasons. She emerged with a judgment that the widow – Vickie Lynn Marshall in court and “Anna Nicole Smith” on stage – was due $474 million from her late husband’s estate.

Since then, the courts have been trying to decide which ruling should be honored: the Texas probate order or the federal bankruptcy decision.

Two years ago, the 9th U.S. Circuit Court of Appeals in San Francisco threw out Ms. Smith’s award entirely and said federal judges had no right to intervene in any matter involving a state’s probate of an estate.

That ruling threatened to crimp the power of federal courts on several fronts. For example, the Internal Revenue Service often goes to federal court to seek taxes that are owed by an estate. For that reason, the Justice Department entered the case of Marshall v. Marshall on the side of Ms. Smith.

Yesterday, the Supreme Court called the 9th Circuit’s decision a mistake. Justice Ginsburg said Ms. Smith had sued over a kind of fraud that deprived her of a gift. She was not contesting the terms of her late husband’s will. But having revived her claim, the court sent the case back to the 9th Circuit. It must decide whether Ms. Smith’s suit was properly in a bankruptcy court in the first place.

Los Angeles lawyer Kent Richland, who represented Ms. Smith, said he was pleased by the Supreme Court’s ruling but acknowledged a legal battle remained.

He will argue that the bankruptcy judge in Los Angeles was the first to rule on Ms. Smith’s claim that she had been cheated, and for that reason, its decision is first.

“Anna Nicole Smith’s claims existed years before her husband died and years before thoughts of probate even began,” Mr. Richland said. “We are confident that the 9th Circuit will have no problem in ruling in our favor on the issues that remain.”