Media mogul Rupert Murdoch’s son filed a statement of claim in the Federal Court on Tuesday, a day after Crikey publisher Private Media’s chairman Eric Beecher and managing editor Peter Fray put their names to an ad in The New York Times inviting Lachlan Murdoch to sue.

“We await your writ so that we can test this important issue of freedom of public interest journalism in a courtroom,” the two media executives said in an open letter to Lachlan Murdoch, which was also published in Australia’s The Canberra Times newspaper on Tuesday.

Murdoch is suing Private Media, a private company, Fray, who is also the website’s editor-in-chief, and Crikey’s political editor, Bernard Keane.

Murdoch claims he was defamed by Keane’s column about the U.S. congressional investigation into the Jan. 6 insurrection which Crikey published on June 29 under the headlines: “Trump is a confirmed unhinged traitor. And Murdoch is his unindicted co-conspirator.”

U.S. cable news giant Fox News is accused in suits filed in the U.S. of airing false claims linking two election technology companies, Dominion and Smartmatic, to a conspiracy to steal votes from former President Donald Trump in the 2020 election, won by President Joe Biden.

Crikey said it welcomed the Murdoch action. “Crikey will not be silenced,” the statement published Wednesday said.

Lachlan Murdoch’s office confirmed the defamation proceedings had been filed but declined to make further comment.

Private Media chief executive Will Hayward said in a statement: “We are determined to fight for the integrity and importance of diverse, independent media in Australian democracy.”

No court hearing date has yet been set. Murdoch has not proposed a monetary sum should he win damages in court.

Crikey removed the contentious article from its website when it received a letter from Murdoch’s lawyers a day after the article was published. After further letters were exchanged between lawyers, Crikey published the article again last week.

Crikey attracts an audience of at least 175,000 unique readers a month and has at least 15,000 paid subscribers, according to court documents.