On social media sites such as Facebook, news stories can sometimes spark thousands of comments, which continue for weeks after the item is posted.
These comments sections and their wide-ranging trails have become a distinctive feature of social-media sites.
But this model is now under question after a court in Australia ruled that media outlets can be sued for defamatory comments that are posted by users below their stories.
The New South Wales Supreme Court's decision has raised serious questions for news outlets, which would be required to somehow check all comments on their Facebook pages - and presumably other social media sites - before publishing. Facebook has expressed concern, saying individuals should be held liable for their comments rather than the media outlets.
The ruling follows concerns about press freedoms in Australia, which already has some of the world's strictest defamation laws. In recent weeks, questions have been raised about the rights of journalists following two high-profile police raids - on the home of a political reporter and the offices of public broadcaster ABC - over concerns that their stories involved national security breaches.
The court ruling followed a defamation suit by a former youth detainee, Mr Dylan Voller, who had been mistreated while in detention. In stories about him on the Facebook pages of some of the country's main news sites, such as the Sydney Morning Herald and The Australian, users posted comments which he said were defamatory.
In a surprise ruling, Justice Stephen Rothman found that the media outlets could be treated as "publishers" of the comments and be held liable for defamation.
"A defendant cannot escape the likely consequences of its action by turning a blind eye to it," the judge ruled. The media organisations "provided the forum for its publication and encouraged, for their own commercial purposes, the publication of comments".
Rupert Murdoch's News Corp, which publishes The Australian, and is the country's largest newspaper stable, said the decision was "ridiculous".
"This ruling shows how far out of step Australia's defamation laws are with other English-speaking democracies and highlights the urgent need for change," it said in a statement.
In an editorial, The Australian said the judge ignored the role of Facebook, which did not allow posts on its public pages to be switched off.
"This curious judgment, which even Justice Rothman anticipates will be appealed, is another strike in a growing number of blows to the media under inadequate, badly designed or outdated laws that make it difficult for us to do our job of informing the public," it said.
The judgment also raised questions about the obligations of news outlets to vet their social media pages.
An expert on online media, Dr Fiona Martin from the University of Sydney, said the decision may require all businesses in Australia that have Facebook pages to hide their comments before allowing them to be seen by the public.
"The problem is that Facebook was not designed for users to pre-moderate comments," she wrote on The Conversation website.
"Hiding comments will stop many people from posting, because they won't see their contributions appear as they do elsewhere on Facebook. It will also stymie conversations, unless companies hire 24/7 moderation services."
Some legal experts said the decision could potentially extend to personal Facebook pages, meaning that all users would be liable for comments on their pages. It is not clear which other social media sites the ruling could apply to.
The decision comes amid growing debate about press freedom in Australia.
Following the recent raids on journalists, a parliamentary inquiry was announced late last week to look into the impact of security agencies and police on press freedoms.