Antitrust case against Apple on its last legs

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The antitrust lawsuit against Apple is on its last legs after a federal judge dismissed the plaintiffs' last remaining witness.

Judge Yvonne Gonzalez Rogers said Monday she was "concerned" and "troubled" by the remaining plaintiffs' witness in the class action case.

The judge scolded the plaintiffs in court, calling witness Marianna Rosen "inadequate" since the suit was brought by her husband's law firm, and ordered the plaintiffs lead attorney Bonny Sweeney to produce a new witness for Tuesday's court session, in Oakland, California.

The issue is that Rosen and her attorneys did not provide complete information about the iPods she introduced as evidence. And that came to light only after Apple's legal team argued that the devices she purchased were not among those affected by the lawsuit.

Apple's lead attorney William Isaacson suggested the case should be thrown out, but the judge said the merits of the class-action case should still go before the jury.

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The case, which was initially filed over a decade ago, concerns older versions of Apple's iPod music devices. Those iPods played only songs bought from the iTunes stores or songs downloaded from compact discs—not from rival companies.

The plaintiffs allege Apple's behavior was anticompetitive, and they are seeking damages of at least $350 million, though if the company is found to have violated antitrust laws it could be ordered to pay more than $1 billion.

Apple suit in question
Apple suit in question

Monday's court testimony was dominated by a Stanford economist who produced a detailed study, paid for by the plaintiffs legal team.

Professor Roger Noll testified that Apple tried to maintain an illegal monopoly on digital music from 2006 to 2009.

But the drama came later, when Judge Gonazlez Rogers' castigated the plaintiffs. Still, the judge said Apple's own records show that there are at least 8 million consumers who purchased iPods, and their interests were still at stake in the trial.

The judge questioned whether she would be able to accept a jury verdict without a remaining named plaintiff. Apple contends that without a named plaintiff the case can't continue.

"This $1 billion case is now about one half of two iPods," Isaacson said in a court filing.

Read MoreRead some of Steve Jobs' videotaped testimony in the case

Gonzalez Rogers can decide there is no case after the jury reaches a verdict. In that event, Isaacson said, "the verdict is null and void no matter who wins."