California- Oakland, Calif., attorney Christopher Grell’s belief that certain Internet speech shouldn’t be immune from liability was bombing Tuesday during oral arguments in the state Supreme Court.

But the coup de grace came when Justice Ming Chin followed up Grell’s presentation by immediately telling one of the opposing lawyers how surprised he was by Grell’s “startling lack of legal authority.”

That statement apparently summed all seven justices’ thoughts about Grell’s argument, and effectively signaled that the court doesn’t intend to make untold numbers of Internet users liable for every allegedly defamatory posting on the Web.

Chin even pointed out that Grell’s opponents — Oakland attorney Mark Goldowitz and Ann Brick, of the American Civil Liberties Union of Northern California — had “plenty” of legal authority on their side.

Goldowitz represents Ilena Rosenthal, a women’s health advocate accused of posting an allegedly defamatory opinion piece with two online newsgroups in August 2000. The editorial by co-defendant Tim Bolen attacked retired Pennsylvania psychiatrist Stephen Barrett and Canadian doctor Terry Polevoy for their stance against alternative medicines.

The article accused the two men of using false information and intimidating tactics, and said Barrett had stalked a woman who hosted a Canadian television show about untraditional therapies.

Alameda County Superior Court Judge James Richman threw the two men’s libel suit out in 2001, but San Francisco’s 1st District Court of Appeal reinstated Polevoy’s claims in 2004. The appeal court held that §230 of the federal Communications Decency Act didn’t immunize Rosenthal.

An e-mail from Barrett threatening to sue Rosenthal, the 1st District ruled, put her on notice that she could be held liable for republishing Bolen’s letter.

Dozens of amici curiae — most of them online companies such as Amazon.com and Earthlink Inc. — joined Rosenthal in arguing that the appeal court’s ruling could chill free speech.

“If, simply by receiving ‘notice,’ service providers were potentially liable for the unimaginable volume of third-party content that constantly flows through their services,” the companies’ lawyer, Samir Jain, wrote, “they would have little choice but to automatically and immediately take down and block third-party content in response to virtually all complaints.”

Jain, a partner in Washington, D.C.’s Wilmer Cutler Pickering Hale & Dorr, argued that notice-based liability would “unleash a ‘heckler’s veto’ that would suppress swaths of entirely legitimate content.”

On Tuesday, the California Supreme Court seemed to agree and also stressed the fact that the 1st District ruling differed from all others around the country.

The justices noted that most courts — even two other appellate courts in California — had agreed with Zeran v. America Online Inc., 129 F.3d 327. That 1997 seminal ruling by the Virginia-based 4th U.S. Circuit Court of Appeals said Internet users — unlike publishers — aren’t liable for posting online content.

“The court of appeal ruling here,” Justice Joyce Kennard said, “seems to stand completely on its own. Zeran has been followed widely.”

A few justices also seemed concerned that a California Supreme Court ruling contrary to Zeran and its progeny could result in forum-shopping, with Internet users trying to remove suits to the federal courts.

No one, Justice Carol Corrigan said, would want to be found liable in California. “I think there is that danger, yes,” Goldowitz replied.

Corrigan also stepped in when Grell tried to argue that the Internet should be held to the same liability standards that apply to newspapers and magazines. “Isn’t the whole point here that the Internet is different?” Corrigan asked.

Grell was asked several times to point to legal authority that would support his case, but more often responded by arguing public policy reasons that immunity shouldn’t apply to postings by third-party users.

Congress had intended to contain allegedly defamatory actions, he said. “To grant absolute immunity would basically allow Pandora’s box to remain open,” he added. Soon thereafter, Chin slammed Grell with his comment about a “startling lack of legal authority.”

A ruling in Barrett v. Rosenthal, S122953, is due within 90 days.