FOX Corp Chairman Rupert Murdoch acknowledged under oath that some Fox hosts "endorsed" the notion that the 2020 U.S. presidential election was stolen, according to a court filing unsealed Monday.

Murdoch's acknowledgment is included in a filing from Dominion Voting Systems, part of the voting technology firm's $1.6 billion defamation lawsuit against Fox News and parent company Fox Corp over Fox's coverage of the 2020 presidential election.

Documents in the case in Delaware state court show Murdoch and other Fox executives believed Joe Biden fairly beat Donald Trump and that the results were not in doubt.

Murdoch's testimony is from his deposition in the lawsuit. Reuters has not viewed all his testimony because it remains under seal.

Asked by a Dominion lawyer if some of Fox’s commentators had endorsed the idea that the 2020 election was stolen, Murdoch responded, “Yes. They endorsed,” according to the filing.

When questioned, Murdoch said “some of (Fox’s) commentators were endorsing” the narrative of a stolen election, including “maybe Lou Dobbs” and “maybe Maria (Bartiromo).”

Murdoch's testimony and other material in the filing shed light on Fox's internal deliberations as it covered the election-rigging claims and sought to avoid losing viewers to far-right competitors that embraced Trump's false narrative.

Fox has argued that its coverage of claims by Trump's lawyers were inherently newsworthy and protected by the First Amendment of the U.S. Constitution.

Dominion's reputation is also at stake as it seeks to recover from what it has described as irreparable harm to its business.

A five-week trial is scheduled to begin on April 17.

Dominion has argued that internal communications and depositions by Fox personnel prove the network knowingly spread falsehoods about Trump's loss in the 2020 U.S. presidential election in order to bolster its ratings.

Dominion claims in its filing that Murdoch closely monitored Fox coverage but declined to wield his powerful editorial influence despite strong concerns about Fox's coverage.

Murdoch testified that he believed early on that "everything was on the up-and-up" with the election, and that he doubted claims of election fraud from the very beginning.

Asked by a Dominion lawyer if he could have prevented Trump's lawyer Rudy Giuliani from continuing to spread falsehoods about the election on air, Murdoch responded, "I could have. But I didn't," according to Dominion's filing.

Dominion's filing opposes Fox's motion for summary judgment, which seeks a ruling in the media company's favor that would preempt the need for a trial on certain legal issues.

In its own filing made public Monday, Fox argued that its coverage of statements by Trump and his lawyers were inherently newsworthy and that Dominion’s “extreme” interpretation of defamation law would “stop the media in its tracks.”

“Under Dominion’s approach, if the President falsely accused the Vice President of plotting to assassinate him, the press would be liable for reporting the newsworthy allegation so long as someone in the newsroom thought it was ludicrous,” Fox said.

Dominion sued Fox News Networks and parent company Fox Corp FOXA.O in March 2021 and November 2021 in Delaware Superior Court, alleging the cable TV network amplified false claims that Dominion voting machines were used to rig the 2020 election against Trump, a Republican who lost to Democratic rival Biden.

In a statement Monday, a Fox spokesperson said Dominion's view of defamation law "would prevent journalists from basic reporting and their efforts to publicly smear Fox for covering and commenting on allegations by a sitting President of the United States should be recognized for what it is: a blatant violation of the First Amendment.”

Dominion’s motion for summary judgment, filed this month, was replete with emails and statements in which Rupert Murdoch and other top Fox executives say the claims made about Dominion on-air were false – part of the voting machine company’s effort to prove the network either knew the statements it aired were false or recklessly disregarded their accuracy. That is the standard of “actual malice,” which public figures must prove to prevail in a defamation case.