SAN JOSE — Saying they need to pay more money, a federal judge on Friday rejected a proposed $324.5 million settlement in a high-profile lawsuit that accused Apple, Google and other Silicon Valley companies of colluding to not recruit each other’s employees.

In a strongly worded decision, U.S. District Judge Lucy Koh said the proposed payment, though endorsed by attorneys on both sides, fell short of “reasonableness” in a case where “there is ample evidence of an overarching conspiracy” among the companies.

The case has rocked Silicon Valley with revelations that the late Apple co-founder Steve Jobs played a central role in a scheme involving top executives at leading companies, including former Google CEO Eric Schmidt and Intel’s former chief, Paul Otellini. Tech workers who brought the suit had asked for $3 billion in damages, arguing that the no-poaching deals were anti-competitive and made it harder for them to negotiate raises or get better jobs.

Attorneys for both sides in the dispute negotiated the settlement just a month before they were scheduled to begin trial this spring. But one of the original plaintiffs, former Adobe engineer Michael Devine, filed a formal objection that called the agreement “grossly inadequate.”

The settlement would have provided $81 million to plaintiffs’ attorneys who brought the lawsuit, while providing an average of $3,750 for each of about 64,000 affected workers, Koh estimated.

That would be less than the amount paid to individual workers under an earlier settlement that involved related allegations, which was reached last year by three smaller companies — Intuit, Pixar and Lucasfilm — at a time when Koh said the workers’ case wasn’t nearly as strong.

“The remaining defendants should, at a minimum, pay their fair share as compared to the settled defendants,” Koh wrote in her 32-page decision, after calculating that a proportional settlement for Apple, Google, Intel and Adobe would be at least $380 million.

The ruling, and Koh’s assessment of the evidence, puts new pressure on those companies to resolve the case rather than risk a trial where the plaintiffs were seeking at least $3 billion.

“This does give the plaintiffs’ lawyers more leverage,” said Stephen Hirschfeld, a veteran San Francisco employment lawyer who is not involved in the case. “When something like this happens, it is going to put additional pressure on the defendants to come up with more money.”

While it’s unusual for judges to reject a settlement that was endorsed by attorneys on both sides of a dispute, Hirschfeld said it’s happening more often.

“It used to be up to the parties to work out a settlement and judges would pretty much rubber-stamp them,” he said. “But there’s been a lot of criticism of class-action settlements — that plaintiffs are not recovering as much as they can, or the plaintiffs’ lawyers are getting too much, and the defendants are getting off cheap. So there’s more pressure on the judges to make sure that settlements are reasonable and fair.”

Attorneys for the workers, including Devine, couldn’t be reached for comment Friday. They had argued in a court filing that the proposed settlement “is presumptively fair because it is the result of years of hard-fought litigation and arm’s length negotiations conducted by capable counsel.”

Spokesmen for Apple, Google and Adobe declined to comment. Intel said in a brief statement: “We are disappointed that the Court has rejected preliminary approval of an agreement that was negotiated at arm’s length over many months.”

But University of San Diego employment law professor Orly Lobel praised Koh’s decision.

“This case had egregious behavior by the defendants for a long time,” Lobel said, noting that the workers had overcome a significant legal hurdle in convincing Koh to grant class-action status to their claims. “It does seem unreasonable to have settled it for so little at this stage, after the class was approved.”

Some of the most damning evidence came from emails and testimony by Silicon Valley luminaries, according to Koh’s ruling, which described cozy relationships between “key players” — including Jobs, Schmidt and longtime valley executive Bill Campbell, who was chairman of Intuit, a director at Apple and a corporate adviser at Google — during the period of 2005 to 2009.

Jobs, in particular, “was a, if not the, central figure in the alleged conspiracy,” Koh wrote. After hearing that Google was trying to recruit Apple workers, Jobs allegedly threatened Google co-founder Sergey Brin, who testified that Jobs told him, “If you hire a single one of these people that means war.”

Citing threats Jobs made against Adobe, Koh added that “other defendants’ CEOs maintained the anti-solicitation agreements out of fear of and deference to Mr. Jobs.”

Schmidt, who also sat on Apple’s board, fired at least two Google recruiters when Jobs complained they were contacting Apple employees, Koh wrote. Google also dropped plans to hire several former Apple engineers after Jobs objected.

While acknowledging the plaintiffs aren’t guaranteed to win at trial, Koh said the evidence suggests the agreements gave companies less incentive to raise workers’ pay. Google did approve big raises, she noted, after the company decided it had to stave off hiring by Facebook, which had refused to enter into a no-poaching pact.

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