The ruling, which overturns a lower court's ruling on internet libel, covers publishers of other people's comments, such as blogs, discussion lists, ISPs and individuals running their own sites. It says that a libelled person must sue the individual who made a libellous comment, not the person or company who allowed it to be published.
The ruling was made in a case taken by two doctors against Ilena Rosenthal. Rosenthal posted an email from someone else relating to a Dr Barrett to a newsgroup. Barrett sued for defamation but the case was dismissed. That dismissal was overruled by the California Court of Appeal, but the California Supreme Court in turn reversed that ruling and said that Rosenthal was not liable.
The case concerned Section 230 of the Communications Decency Act, a section which says that "no provider or user of an interactive computer service shall be treated as the publisher or speaker of any information provided by another information content provider".
"Courts have consistently interpreted Section 230 to provide broad protections for the platforms upon which free speech has flourished online," said Kurt Opsahl, a staff attorney at the Electronic Frontier Foundation, the digital rights body which filed a brief in support of Rosenthal.
"By reversing the Court of Appeal, the California Supreme Court has brought California back in line with other jurisdictions and reaffirmed the critical rule that the soapbox is not liable for what the speaker has said."
Justice Carol Corrigan said in the ruling that the law had been drafted in order to protect free speech. "The prospect of blanket immunity for those who intentionally redistribute defamatory statements on the internet has disturbing implications," she wrote. "Nevertheless, by its terms section 230 exempts Internet intermediaries from defamation liability for republication. The statutory immunity serves to protect online freedom of expression and to encourage self-regulation, as Congress intended."
The case was the first in which section 230 immunity has been invoked by an individual who had no supervisory role in the operation of the website where allegedly defamatory material appeared. The immunity's protection of service providers had already been established when an individual, Kenneth Zeran, unsuccessfully sued AOL for unreasonable delay in removing defamatory messages.
The email posted by Rosenthal, which Dr Barrett* said was defamatory, said that "Dr Barrett is arrogant, bizarre, closed-minded; emotionally disturbed, professionally incompetent, intellectually dishonest, a dishonest journalist, sleazy, unethical, a quack, a thug, a bully, a Nazi, a hired gun for vested interests…" and continued in a similar vein. A similar statement was published about a Dr Polevoy.
The court noted that, "At some point, active involvement in the creation of a defamatory Internet posting would expose a defendant to liability as an original source. Because Rosenthal made no changes in the article she republished on the newsgroups, we need not consider when that line is crossed."
Struan Robertson, editor of OUT-LAW.COM and a technology lawyer with Pinsent Masons, said the case highlights a major difference between US law and UK law on the duty to remove defamatory postings.
"In the UK, service providers have a duty to remove or block access to defamatory material that they host once they are made aware of it. They can be sued if they fail to do so expeditiously," he said. "The same approach is taken across Europe; but the US considers this to be an impossible burden on service providers and anathema to free speech."
Robertson said this leaves victims of defamation in an impossible situation. "Under US law, you can sue your defamer but you can't force a third party to take the offending comments off-line. This is inconsistent with US law on copyright, where a statutory notice-and-takedown procedure gives effective remedies to rights holders."
Judge Corrigan acknowledged section 230's immunity has "some troubling consequences" but wrote: "Until Congress chooses to revise the settled law in this area … plaintiffs who contend they were defamed in an Internet posting may only seek recovery from the original source of the statement."
* Editor's note, 27/11/2006: This story originally stated that the court said the comments about Dr Barrett were defamatory. However, as Ilena Rosenthal pointed out to OUT-LAW today, it was Dr Barrett's complaint that said these comments were defamatory. We apologise to Ms Rosenthal for this inaccuracy. The story has been corrected today.