The defamation battle over media responsibility for social media comments isn't over yet, and may get even messier.

Dylan Voller, famously restrained in a "spit hood" while in child detention, continues through his defamation case to wreak an appropriate revenge on the media companies that treated him as worthy click bait.

The latest instalment comes from the NSW Court of Appeal, dealing with the appeal of Justice Stephen Rothman's earlier pre-trial finding that media companies are publishers of the defamatory comments that readers leave on their Facebook pages.

To recap: Voller is suing three media companies over Facebook comments posted in response to stories they had published about him. The preliminary issue was whether, since they don't write the comments or actively moderate them, they could be said to have "published" them. You can only be liable for defamatory material if you were intentionally involved in the act of publishing it.

The appeal judges said that Rothman was not wrong, affirming that the media companies are potentially liable as publishers of the comments on the Facebook pages that they maintain.

As I've said before, the main problem here is the current defamation law's insistence that the internet is just another medium for communication, no different from print, television or a book.

The media companies were reduced to running silly analogies: they suggested that their role in the publication of Facebook comments is akin to that of a paper supplier to a newspaper publisher or the seller of a computer to an author.

The court thought a better analogy would be a talkback radio station, which allows an open microphone to members of the public to have their say. The law has always held that if you broadcast or publish defamatory things that other people say you're liable for it.

In the end, the judges said it was simple: media companies set up their Facebook pages to post articles and videos there, with the intention of attracting eyeballs. At the bottom of each they say "comment", and that's a deliberate invitation that they have made.

Whatever then gets posted there, they have played an intentional role in publishing it. End of story. But it's not the end of the story, either in relation to the ultimate liability of the media or the bigger picture of defamation law reform.

Rather lost in the breathless reporting of this case are a couple of key technical points. In short, the media may well still win the Voller case, and probably will.

Establishing that they published the comments is just step one. Assuming the comments were defamatory (they were), the appeal court has left open two viable lines of defence for the media.

One is innocent dissemination, which is a complete defence to a defamation claim and can be raised by a "secondary" publisher who was neither aware nor should have been aware of the defamatory material.

Once put on notice, the situation changes, but until then they can rely on this defence.

Although Rothman had found that the media are primary publishers of the comments, and therefore this defence would be unavailable to them, the appeal court kicked that out without deciding either way itself. It's still open to be run at trial, and it has good legs.

The second point was one raised by none of the parties, but which several other media companies argued during their attempt to intervene in the appeal. The appeal court refused to let them in, but their argument got some air time and is a good one.

It's a constitutional issue about the interaction of state-based defamation law and a Commonwealth law, the Broadcasting Services Act 1992 (which governs the internet). There is a provision in the act that invalidates any state law that would attach liability to someone who hosts internet content where they are not aware of what that content is

We can expect the media defendants to now include that argument in their defences against Voller's claim. The issue of what they knew and should have known will be key to the ultimate resolution of the case.

In the meantime, though, the preliminary issue is probably heading for the High Court. The media is spitting with anger that it keeps getting hammered with legal responsibility for things that other people put online, while the social media companies have no liability at all.

From the perspective of the current law, that's just tough. Facebook supplies the billboard, but the media company puts the billboard on its virtual premises, covers it with its branding and begs the public to come and post shit on it. If the contest is one of who's most responsible, the answer is clear.

However, there remains a flaw in the commercial logic: Facebook is not just the blank page supplier it claims to be. It's a media company in its own right, as is Google, and they now dominate the landscape because most of the advertising dollars and audience eyeballs are concentrated under their control.

The law is not catching on to that underlying reality and won't until it is radically reformulated in ways that courts cannot do. That's a job for parliament.

That's a job for parliament.

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