Redstone filed his own lawsuit in Los Angeles seeking court approval of his decision to fire Dauman and Abrams. The lawsuit, which seeks to have the dispute heard in California, was filed on the same day Dauman filed his complaint in Massachusetts. Shares of Viacom, which were down more than 40 percent last year, have rallied in the wake of Redstone’s moves.

The billionaire said June 3 that he had the backing of four out of seven trustees, which means Dauman and Abrams will be out of the trust even if they win their case.

At the heart of Dauman’s complaint is the contention that Redstone isn’t speaking for himself. He argues that Redstone suffers from dementia and is under the undue influence of his once-estranged daughter in a plot to take control of the trust’s majority stakes in Viacom and CBS Corp.

Undue Influence

Fagen told Phelan on Tuesday that while the trust agreement doesn’t define the term “undue influence,” the burden of proof is on Shari to disprove it. Redstone’s trust agreement is private. Lawyers gave Phelan a copy of the documents on Tuesday for review.

Shari Redstone isn’t acting as her father’s fiduciary and isn’t in charge of his care, Kleiger told Phelan. The billionaire, who has an independent care manager, leaves the house to visit family and has friends in Malibu, the lawyer said.

“He is not a prisoner in his own house,” Kleiger said.

He’s in good health and was hospitalized only once since last fall so doctors could monitor his reactions to new medications, Kleiger said. While Redstone’s speech can be difficult to understand, the billionaire says vulgarities “with remarkable clarity,” he added.

Redstone said in court papers that he lost faith in Dauman after he and Abrams acted against his wishes. The duo removed Redstone as Viacom’s chairman, ignored his opposition to shopping a Paramount stake, shunned requests for information and basically treated him “as if he was already gone,” according to the filing. Redstone said he feared Dauman would answer to no one if he held the top two posts at Viacom while controlling the trust.

As an example of Redstone’s lucidity, attorney Kleiger recounted a meeting at the magnate’s home earlier this year in which Redstone asked him to deliver to Viacom executives a message telling them not to sell off Paramount.