A person who is found to have published a defamatory
statement may avail to a defence of innocent dissemination
where it can be shown that they had no knowledge of the defamatory nature of the statement, there was nothing to lead them to believe so, and they were not negligent in failing to discover it.
The defence was first established in Vizetelly v. Mudie's Select Library  2QB 170 (Eng. CA).
Lord Justice Romer held that a person will not be liable for defamation where:
- That [they were] innocent of any knowledge of the libel contained in the work disseminated by [them], that there was nothing in the work or the circumstances under which it came to [them] which ought to have led [them] to suppose that it contained a libel, and that, when the work was disseminated by [them], it was not by any negligence on [their] part that [they] did not know that it contained the libel, then, although the dissemination of the work by [them] was primâ facie publication of it, [they] may nevertheless, on proof of the before-mentioned facts, be held not to have published it
Romer L.J., at 180, also noted that the defence places a heavy burden upon the defendant to show that they were not negligent.
In the US there is a similar defence available under section 581 of the Second Restatement of Torts (1977).