Media boss Lachlan Murdoch has launched defamation proceedings in the Federal Court against the company which owns news website Crikey.
Mr Murdoch's lawyers filed a statement of claim in the Federal Court on Tuesday afternoon, against Private Media, over an article linking his family to the January 6 insurrection in the US.
The analysis article, written in June by political editor Bernard Keane, named "the Murdochs" as "unindicted co-conspirators" in the deadly attack on Washington's Capitol carried out by former president Donald Trump's supporters.
It also published a series of legal letters sent to Crikey by the News Corp and Fox chairman's lawyers.
The statement of claim said Murdoch is a well-known Australian "with a substantial reputation throughout Australia and elsewhere".
It alleges the article contained more than a dozen defamatory imputations, including that Mr Murdoch "illegally conspired" with Mr Trump to overturn the 2020 election result and to incite an armed mob to march on the Capitol.
The document claims allegations of criminality and "sensational language" used in the article caused serious harm to Mr Murdoch's reputation.
The article was removed from the Crikey website about 20 minutes after an initial legal letter was sent, but was later republished to "clarify" media reports about legal threats.
Crikey's lawyers, in correspondence, said there was no evidence Mr Murdoch did any of the things described in legal letters and denied Crikey had said he did.
Mr Murdoch's statement of claim said Crikey's website has an audience of at least 175,000 unique readers per month and at least 15,000 paid subscribers.
It said the article was promoted as "free to read" on social media as well as in its newsletter and appeared at the top of the home page.
Mr Murdoch's lawyers allege what followed constituted a "disingenuous campaign" to promote and republish the article, including by way of an advertisement in The New York Times which invited Mr Murdoch to commence proceedings.
Crikey's editor and publisher publicly challenged Mr Murdoch to sue the company in the ad.
Editor-in-chief of Crikey Peter Fray said it was "absurd" to prevent media in Australia discussing events of the January 6 riots in a similar way to how they were reported on in the US.
In an article published on Monday, Private Media chairman Eric Beecher claimed Mr Keane's article did not directly reference Lachlan Murdoch.
Mr Beecher also claimed the legal threats represented an "abuse of media power in Australia".
He wrote that the word "Murdoch" only appeared in the article twice, which focused largely on Trump's role in the state of US politics.
"The Murdochs and their slew of poisonous Fox News commentators are the unindicted co-conspirators of this continuing crisis," he wrote in the last line of the article.
In a statement, both Mr Fray and Mr Beecher said they were determined to fight for diverse independent media in Australia.
"Crikey's Murdoch Letters series this week reveals how media power works in this country. We believe that coverage of the events of January 6 at the US Capitol, and the role of Fox News in those events, is absolutely legitimate," the statement said.
"We welcome the chance to test what an honest, open and public debate actually means for free speech in Australia."
A first court date is yet to be set down.
Mr Murdoch's lawyer, John Churchill, was contacted for comment.
