Defamation Act 2013: "S.5 (1)This section applies where an action for defamation is brought against the operator of a website in respect of a statement posted on the website.
(2)It is a defence for the operator to show that it was not the operator who posted the statement on the website.
(3)The defence is defeated if the claimant shows that—
(a)it was not possible for the claimant to identify the person who posted the statement,
(b)the claimant gave the operator a notice of complaint in relation to the statement, and
(c)the operator failed to respond to the notice of complaint in accordance with any provision contained in regulations.
(4)For the purposes of subsection (3)(a), it is possible for a claimant to “identify” a person only if the claimant has sufficient information to bring proceedings against the person." 'via Blog this'