10/16/00- Updated 05:28 PM ET

Court: Unsigned Net postings unprotected

MIAMI (AP) — In a ruling that challenges online anonymity, a Florida appeals court declared Monday that Internet service providers must divulge the identities of people who post defamatory messages on the Internet.

Critics of the ruling say it could have a chilling effect on free expression in Internet chat rooms.

The ruling comes against the efforts of the American Civil Liberties Union to protect the identity of eight individuals who posted anonymous missives on a Yahoo! financial chat room about Erik Hvide, the former CEO of Hvide Marine.

Hvide alleges that personal attacks against him also caused damage to the company's image.

Hvide's attorney Bruce Fischman hailed the ruling, saying it would force Internet users to ''think a bit before they speak.''

The ACLU had wanted the court first to rule on whether Hyde had actually been defamed before identifying the defendants, named in court papers only as John Doe. If there was no showing of defamation, the ACLU reasoned, the critics should remain anonymous.

However, on Thursday, the court dissolved a stay freezing subpoenas for the records of Yahoo! and America Online, whose service was used by one of the defendants in the defamation case.

Lauren Gelman, public policy director with the Electronic Frontier Foundation, is concerned that other courts could follow the lead of the 3rd District Court of Appeals in approving subpoenas.

''This kind of speech happens all the time in all kinds of chat rooms,'' Gelman said. ''We don't want to see these subpoenas become regularly used to cause people to self-censor themselves.''

Both Internet companies took a back seat in the lawsuit, saying they would do whatever the judges said.

Lyrissa Lidsky, who argued the case on behalf of the ACLU, called the decision a surprise and a setback.

Nevertheless, she said, ''It's not a defeat for all the other John Does in the pipeline'' fighting Internet-related subpoenas because the court did not explain its legal reasoning.

An appeal is being explored.

''The court had the potential to set an important precedent about the right to speak anonymously on the Internet,'' Lidsky said. ''The courts are eventually going to have to come to grips with this issue and decide how broad free speech rights are in cyberspace.''

The issue is largely untested in the nation's courts.

A Virginia federal judge sided with a government subpoena request in a criminal case, but civil suits in California and Virginia have not settled the subpoena questions involving anonymous Internet users.