Rambus successfully fended off an attempt by opponents in an upcoming $4.38 billion antitrust trial to use a recent negative court ruling over document shredding against the chipmaker.

Jurors will not be told by the court that Micron and Hynix <000660.KS> have already proven that the chipmaker shredded documents as part of its legal strategy, a California judge said at a hearing on Tuesday. Instead, the Rambus opponents will have to present evidence on that issue.

Rambus shares closed up 6.3 percent on news of the ruling.

Rambus accuses Micron and Hynix of boycotting its RDRAM memory technology, according to its lawsuit. Micron and Hynix improperly colluded to restrict production and raise the price of Rambus chips, the lawsuit alleges.

The company claims up to $4.38 billion in lost profits. Micron and Hynix deny any anticompetitive conduct.

Last month, the U.S. Court of Appeals for the Federal Circuit found Rambus was wrong to shred hundreds of boxes of documents relevant in two patent infringement lawsuits it filed, sending its shares down 18 percent in one day.

In the antitrust case, attorneys for Micron and Hynix said the Federal Circuit ruling proves Rambus had a duty to preserve documents in anticipation of litigation, and that it should not have to be demonstrated at trial. Rambus opposed their request.

At a hearing on Tuesday in a San Francisco state court, Judge James McBride rejected the Micron and Hynix bid. McBride said he did not want to disturb a prior ruling from one of his colleagues in San Francisco, which had sided with Rambus on how the shredding impacts the antitrust case.

I don't find any reason to change original ruling, McBride said.

Opening statements in the case are expected to begin next week.

Rod Lewis, Micron's vice president of legal affairs and general counsel, said the federal appeals court ruling demonstrates Rambus's bad faith.

We look forward to presenting these facts to the jury at trial, Lewis said in a statement.

A Hynix representative could not be reached, while a Rambus spokeswoman declined to comment.

Much of Rambus' income comes from patent licensing, and it has initiated litigation against a range of tech companies. Winning patent cases makes it easier for Rambus to negotiate additional licensing arrangements.

Rambus settled its antitrust claims against Samsung <005930.KS> last year in a deal worth up to $900 million.

At the hearing on Tuesday, Micron attorney Patrick Shields said Rambus anticipated both antitrust and patent litigation at the time it shredded documents, and so the negative Federal Circuit ruling could come into play.

But Rambus attorney Sean Eskovitz argued that the Federal Circuit ruling only applied to Rambus's patent litigation, and not the antitrust case.

The case in Superior Court of the State of California, County of San Francisco is Rambus Inc. v. Micron Technology Inc. et al, 04-431105.

(Reporting by Dan Levine, editing by Lisa Von Ahn, Dave Zimmerman, Gary Hill)