The High Court has previously ruled that defamation on internet bulletin boards is akin to slander rather than libel.

Mr Justice Eady stated that posts on bulletin boards "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'."
As such "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...People do not often take a 'thread' and go through it as a whole like a newspaper article. They tend to read the remarks, make their own contributions if they feel inclined, and think no more about it."

Mr Justice Eady said that the comments were likely to be considered as 'fair comment' i.e. they cannot be considered as defamatory if they are posted without malice and represent the posters honest views: "I referred to common themes in the postings, such as that of 'bullying' other users and making 'threatening demands' for money. That is classic fair comment territory and, in the light of the modern authorities, it is inconceivable that a jury would find any of those who expressed such a view 'malicious' let alone all of them...Opinions may be expressed in exaggerated and strident terms; the only requirement is that they be honestly held. It is fanciful to suppose that any of these people did not believe what they were saying. Even if they reached their conclusions in haste, or on incomplete information, or irrationally, the defence would still avail them."

Defamation has always been notoriously difficult to prove in court.
Courts generally agree that an opinion, no matter how malicious, is not the same as a stated fact.