Some of Australia's biggest media outlets will learn today whether they have won a High Court bid to distance themselves from Facebook comments at the heart of defamation action by former Northern Territory detainee Dylan Voller.

The image of the young detainee, shackled to a chair wearing a spit hood, first shown by the ABC's 4Corners program, captured the nation's attention.

It sparked a Royal Commission into youth detention in the Northern Territory. 

It was big news in Australia, but not all of it was welcome, with stories from the media outlets posted on Facebook drawing all kinds of comments from the public.

The former detainee, Dylan Voller, is now hoping to sue outlets including The Sydney Morning Herald, The Australian, the Centralian Advocate and Sky News for publishing defamatory Facebook posts about him.

But his case against them in the NSW Supreme Court has stalled, after questions arose over whether the outlets were considered the publishers of the Facebook comments, which were posted in reply to articles written between July 2016 and June 2017. 

It is an important question being considered by the High Court, which may have implications for how media operations manage platforms like Facebook in the future.

Media companies say they weren't the publishers of defamatory comments

At the core of the case is the definition of publishing.

Lawyers for the media groups told the High Court they may have facilitated the process but they were not the publishers of the material.

But lawyers for Mr Voller have told the High Court that under the law, communication of a defamatory comment does not have to be done intentionally.

"Any degree of participation in that process of communication, however minor, makes the participant a publisher," the submissions say.

One of the difficulties for the media groups at the time was that Facebook did not allow them to turn off the comments function.

That has now changed.

News outlets had 'other options' to avoid publication

But lawyers for Mr Voller said there were other options available to media outlets to prevent the comments in question.

"It was practicable to attempt to hide substantially all comments (by specifying a list of extremely common words) and it was also practicable (albeit at a cost) to attempt to have staff review every hidden comment before it was made public," their submissions say.

Mr Voller has not suggested any of the media outlets failed to remove the material once they were aware of it.

Today's decision by the High Court may simply set the ground rules for the defamation action for when it is finally heard. 

At this point, there has not even been a ruling about whether the comments were defamatory.

If the media groups win, it will strengthen their defence.

If they lose, there are other arguments available including innocent dissemination – but that will be a battle for another day.