Rupert Murdoch’s three adult children will retain control over their father’s media empire upon his death, a Nevada court has ruled after Murdoch launched a campaign to wrest away their power and give it all to his oldest son.

The New York Times reported on Murdoch’s loss, citing a sealed court decision that was filed on Saturday. The family battle happened outside of the public’s eye, despite attempts from the media to gain access to the trial.

Murdoch took three of his adult children, James, Elisabeth and Prudence, to court as he tried to completely remove their voting power over the trust Murdoch set up. Murdoch wanted to give Lachlan, his oldest son and most likeminded child, complete control over the media companies.

After reviewing the case, the Nevada commissioner Edmund Gorman concluded that Rupert and Lachlan Murdoch had acted in “bad faith” in their attempts to change the terms of an irrevocable trust that divides control of the company between Murdoch’s four oldest children.

The 96-page opinion lambasts the media mogul, according to the Times, accusing him of organizing a “carefully crafted charade” to “permanently cement Lachlan Murdoch’s executive roles” inside the empire “regardless of the impacts such control would have over the companies or the beneficiaries” of the family trust.

Murdoch is said to have dubbed the attempt to change the trust “Project Harmony” and believed it would see off the prospect of a power struggle within the family after his death. But his children were reportedly blindsided by the move.

Lawyers for the mogul are set to appeal the decision but if it holds, it is likely to have a major impact on the future of the rightwing media empire, which includes Fox News, the Wall Street Journal, the Times and the Sun in the UK and the Australian.

Murdoch, 93, is more politically aligned with Lachlan, his heir apparent. James, Elisabeth and Prudence are regarded as less conservative and James, in particular, has publicly criticized climate denialism in the media and accused US media of “propagating lies” that unleashed “insidious and uncontrollable forces” after the January 6 insurrection.