Though there are few verdicts to help lawyers and site moderators come up with hard and fast rules, it is generally believed that a web publisher who does not pre-screen user comments is not liable for libellous or otherwise unlawful comments because they had no editorial involvement in them.
Sites which pre-screen all comments are generally deemed to share responsibility with the poster because they have chosen to publish any comments that appear.
But one moderating veteran has said that when unscreened comments appear under news stories the publishers of the site could be liable for them.
"Many lawyers I've spoken to now view the invitation of content – so if you have a comments section at the end of an article on a newspaper site – they view that as inviting comment and therefore you are responsible for it and therefore you probably want to consider pre-moderating all the content that goes there," said Danny Dagan, a moderation consultant who has helped establish online communities for The Sun newspaper, amongst others.
Dominic Sparkes is operations director at Tempero, a moderation firm that spun out of broadcast network ITV. He agreed that the view on news story comments had become common, but said that a recent judgment in the UK by Mr Justice Eady might change that.
That ruling, reported on OUT-LAW.COM, said that comments on bulletin boards and online discussion groups are more like slander than libel because they are more informal.
"I think that does get talked about a lot but I think the Justice Eady case might change that slightly," said Sparkes. "I'm not sure if there's enough case law yet to have a hard and fast rule on that in terms of what is said online."
Mr Justice Eady had written in that ruling: "[Bulletin board posts] are rather like contributions to a casual conversation (the analogy sometimes being drawn with people chatting in a bar) which people simply note before moving on; they are often uninhibited, casual and ill thought out. Those who participate know this and expect a certain amount of repartee or 'give and take'."
"When considered in the context of defamation law, therefore, communications of this kind are much more akin to slanders (this cause of action being nowadays relatively rare) than to the usual, more permanent kind of communications found in libel actions," said the ruling.
Dagen and Sparkes were speaking to technology law podcast OUT-LAW Radio.
John Mackenzie, a litigation partner with Pinsent Masons, the law firm behind OUT-LAW.COM, disagrees with Dagen and Sparkes.
"It is likely that the courts will focus on whether or not a publisher reviewed content, rather than the form of the publication," he said. "It isn't likely to make any difference whether or not it is an invitation to comment or a bulletin board. They amount to much the same thing. If the comments are not moderated, the publisher is probably safe, at least until notified of any allegedly defamatory posting."