|Philippee Dauman, Sumner Redstone|
In the filing, Redstone's lawyers said the claims by Dauman and Viacom board member George Abrams were motivated by "self interest."
A spokesman for Viacom was not immediately available for comment.
Last month, Redstone removed Dauman and Abrams from the trust that would determine the future of CBS and Viacom after controlling shareholder Redstone, 93, dies or is declared mentally incapacitated.
Dauman fired back with a lawsuit questioning Redstone's mental capacity. He argued that the moves to replace him and Abrams on the trust and the National Amusements Inc board would lead to an unlawful corporate takeover by Sumner's daughter, Shari Redstone.
Dauman has asked the court to hold a trial by the end of September. A hearing on that request is scheduled for Tuesday in Massachusetts. Shari Redstone has said her father made his own decisions.
In Friday's motion, Sumner Redstone's attorneys argued that Dauman and Abrams were enacting "an acutely self-interested legal strategy that they began plotting months earlier to secure their tenuous positions with Viacom."
They also said a majority of the other trustees had ratified the removal of Abrams and Dauman. "Plaintiffs are therefore off the trust, and off the board, even if they could somehow prove the allegations in their complaint," the motion said.
Sumner Redstone's privately held movie theater chain National Amusements holds 80 percent of the voting stock in both Viacom and CBS.
The mogul's attorneys also asked the Massachusetts court to let the case be handled in California, where Sumner Redstone is seeking an order validating Dauman and Abrams' removal. That request was assigned to Judge David Cowan, who in May dismissed a lawsuit by an ex-girlfriend who claimed Sumner Redstone was mentally incompetent.
The outcome of the court cases, and who ends up controlling the trust and the National Amusements board, will have wide-ranging implications for Viacom and CBS shareholders and could result in changes at the top of both companies, possibly through mergers and acquisitions.