The Delaware Supreme Court has ruled that if an elected official claims that he has been defamed by an anonymous blogger, he cannot use a lawsuit to unmask the writer unless he has substantial evidence to prove his claim.

That standard, the court said on Wednesday, “will more appropriately protect against the chilling effect on anonymous First Amendment Internet speech that can arise when plaintiffs bring trivial defamation lawsuits primarily to harass or unmask their critics.”

At issue was a defamation lawsuit filed last year by Patrick Cahill, a councilman in Smyrna, Delaware. Cahill said he needed the identity of a blogger who in a September 2004 posting praised the mayor but said Cahill was divisive and had “an obvious mental deterioration.”

In a second posting, the blogger, named John Doe in the suit, wrote that Cahill “is as paranoid as everyone in the town thinks he is,” according to court records.

Using a court order, Cahill learned from the publisher of the blog, Independent Newspapers, that the Web address of the blogger belonged to a customer of Comcast. When Cahill demanded the person’s identity, Comcast notified the blogger, as required by law. The blogger filed for a protective order. A lower court judge denied the request, and the blogger appealed.

In their opinion, the five justices reversed the lower court, saying the judge used a standard that was incorrect because it was not stringent enough. The court said, “The Internet provides a means of communication where a person wronged by statements of an anonymous poster can respond instantly, can respond to the alleged defamatory statements on the same site or blog, and thus, can, almost contemporaneously, respond to the same audience that initially read the allegedly defamatory statements.”

David Finger, the blogger’s lawyer, said: “Statements on an electronic bulletin board with hyperbole and profanity are generally not considered as credible sources of facts. The court found that people who read these types of blogs cannot reasonably expect them to be anything more than the writer’s opinion.”

Cahill’s lawyer, Robert Katzenstein, had no comment.

While acknowledging that “the Internet is a unique democratizing medium” that allows “more and diverse people to engage in public debate,” the justices said they made no distinction between “communications made on the Internet and those made through other traditional forms of media in determining the standard to be applied.”

The court said its decision was the first time any state supreme court had ruled on the rights of anonymous bloggers. The U.S. Supreme Court also has not taken a stand in the issue, it noted.

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