His barrister,Bruce McClintock,SC,has told the Federal Court the publications paint Mr Chau as a spy who"betrayed his country"in order to serve the interests of China and the Chinese Communist Party.
The media outlets and McKenzie were relying on a range of defences but a central part of their case was that the claims were substantially true.
The stories alleged Mr Chau funded a $200,000 bribe for a senior United Nations official,an allegation the trio claimed was true by drawing in part on a parliamentary speech given by federal Liberal MP Andrew Hastie in May this year after the investigation was broadcast and published online.
The media outlets suffered a major setback last month when Justice Steven Raresthrew out their truth defence in its entirety,leaving intact only a technical defence of qualified privilege and an argument about whether the defamatory meanings pleaded by Mr Chau were conveyed.
On Friday,the ABC,Fairfax and McKenzie filed an application in the Federal Court for leave to appeal the decision,saying the grounds of appeal"raise important questions of principle"about the defence of truth.
In a statement,a Fairfax Media spokesperson said Justice Rares'decision departed from two"well-established court decisions"in Western Australia and,if it were to stand,"it would severely limit journalists’ ability to do their job by unearthing facts and exposing the truth".
"There has never been a more important time than now to vigorously defend our journalism,and the right of every Australian to be informed about who lives among them,"the spokesperson said.