(Adds Adobe declined to comment, tech companies' request to bar mention of DOJ probe, background)
SAN FRANCISCO, April 15 (Reuters) - Witnesses at an upcoming trial over no-hire agreements in Silicon Valley should not be allowed to offer evidence that Apple co-founder Steve Jobs was "a bully," four major tech companies argued in a court filing.
Tech workers filed a class action lawsuit against Apple Inc , Google Inc , Intel Inc and Adobe Systems Inc in 2011, alleging they conspired to avoid competing for each other's employees in order to avert a salary war. Trial is scheduled to begin at the end of May on behalf of roughly 60,000 workers in the class, and defendants say damages could exceed $9 billion.
The case, which is closely watched in Silicon Valley, is largely built on emails among top executives, including late Apple Chief Executive Steve Jobs and former Google CEO Eric Schmidt.
For instance, after a Google recruiter solicited an Apple employee, Schmidt told Jobs that the recruiter would be fired, court documents show. Jobs then forwarded Schmidt's note to a top Apple human resources executive with a smiley face.
In a joint court filing late last week, the companies told U.S. District Judge Lucy Koh in San Jose, California that they were not seeking to bar Jobs' interactions with other witnesses about the no-hire agreements. However, opinions based on other evidence, like Walter Isaacson's bestselling biography about Jobs, should be kept out of trial.
An attorney for the plaintiffs could not immediately be reached for comment on Tuesday, nor could a representative for Apple. Representatives for Google, Intel and Adobe declined to comment.
"Plaintiffs' only purpose for offering this testimony would be improper - to cast Mr. Jobs in a bad light," the companies said in the filing, adding that such evidence has no bearing on whether any defendant entered into an illegal conspiracy.
"Free-floating character assassination is improper," they wrote.
Apple, Google, Adobe and Intel agreed to settle a U.S. Department of Justice probe in 2010 that barred them from entering into such no-hire agreements in the future. The four companies have since been fighting the civil antitrust class action, arguing that the plaintiffs cannot successfully prove an overarching conspiracy to impact wages.
In addition to evidence about Jobs' character, the tech companies also asked Koh to prohibit discussion of the government probe at trial.
"To admit evidence of the DOJ investigation for any purpose would be unduly prejudicial," they wrote in the filing, "because the jury might incorrectly assume defendants have admitted to or been found guilty of antitrust violations."
At a hearing last month, attorneys for Google and the plaintiffs said they were "making progress" in settlement talks.
Walt Disney Co's Pixar and Lucasfilm units and Intuit Inc have already agreed to a settlement, with Disney paying about $9 million and Intuit paying $11 million. A hearing on final settlement approval is scheduled for May 1.
The case in U.S. District Court, Northern District of California is In Re: High-Tech Employee Antitrust Litigation, 11-cv-2509.
(Reporting by Dan Levine; Editing by Richard Chang)