A New York model is called "a skank" by an anonymous blogger, so she sues Google for the blogger's name.

A Maryland Dunkin' Donuts franchise is called "dirty" by another unnamed blogger, so its owner sues a newspaper website to unmask the critic.

And earlier this month, a local online media forum posts a subpoena from a Pittsburgh woman seeking the identity of an anonymous poster so she can sue for defamation.

As anonymous content proliferates across the Internet -- one 2006 study estimated that 55 percent of American bloggers post under pseudonyms -- so does the opportunity for robust debate, invective, insights, insults and lawsuits.

Just how easy should it be to silence John or Jane Doe holding forth about a school superintendent's cronyism, a company's illegal dumping of toxic waste -- or just claims that a neighbor is of dubious moral character? When is anonymous Internet speech a richly textured exchange of ideas full of nuance, and when is it trash talk?

One local political blogger who goes by the name of The Angry Drunk Bureaucrat views it "like the Supreme Court's view on pornography.

"I know it when I see it," he said in an e-mail -- anonymously -- adding that he is careful to moderate comments that he thinks go too far, and has never been sued.

"Heck, the anonymous pamphleteering that went on between Adams and Jefferson in the early days of the Republic would probably make most bloggers today blush. I'd like to think that we're all part of that old tradition."

Still, in this new digital era, courts are struggling with an increasing number of legal actions against bloggers or the websites that post their comments, searching for ways to balance First Amendment free speech rights with the right to not have one's reputation trashed or privacy invaded online.

Most of these cases can't go anywhere unless the speaker is identified, and that's where the battle begins -- usually with a subpoena aimed at the website provider, says Sam Bayard, assistant director of the Citizen Media Law Project at Harvard University.

"If you don't get the poster's identity, you don't get to bring a lawsuit," Mr. Bayard said, noting that different Web providers have different policies -- some require names, other require just e-mail addresses, some require nothing at all -- from people who register on their site.

Under a 1996 telecommunications law, Web service providers do have protection from comments made by third-party posters, but some courts will require them to divulge those posters' identities if a strong enough case for defamation can be made by the plaintiff.

About a half-dozen John Doe cases have been filed in Allegheny County since 1999, most famously one filed that year involving now-state Supreme Court Justice Joan Orie Melvin, who sought to unmask a blogger Justice Melvin said had defamed her.

While stating that anonymous speech was protected under the First Amendment, Allegheny County Judge R. Stanton Wettick also ruled that she needed the names of her critics to proceed with the case. She later dropped the suit.

In November, Thomas DeRosa, a Forward supervisor, filed a lawsuit in Allegheny County seeking the names of two anonymous posters who suggested on Elizabethboro.com, a community website, that he was corrupt.

"Anytime someone tells lies about you it has an effect on you, especially when they say you're stealing from taxpayers You get angry and upset," Mr. DeRosa said. "They're dealing with the wrong character here."

Richard Rattanni, the website's owner, who runs RSR Tech Web Hosting in Elizabeth, says he doesn't know who wrote the posts, but is refusing to give up the Internet Protocol addresses.

Elizabethboro.com features plenty of harsh language and screeds against President Barack Obama, Secretary of State Hillary Clinton and other public officials, who must meet a tougher burden of proof before proceeding with a defamation suit. But Mr. Rattanni says he is careful about removing abusive remarks about private citizens.

"I'm not for slander, libel or anything like that," said Mr. Rattanni. "It isn't for me to decide. That's up to a judge. So I didn't feel it was right for me to give that information over to him."

In another, more recent case, John Newborg, a lawyer for former Pittsburgh Tribune-Review reporter Karen Roebuck, posted a subpoena on a local media online forum claiming she was defamed on the site and seeking the writer's identity.

The site's owner, Voyager Info-Systems of Beverly Hills, could not be reached for comment.

Since the Media Law Resource Center in New York began tracking data in 2004, 250 legal actions involving bloggers have been filed, although a handful of those date to the 1990s. Since April 2009, at least 50 cases involving anonymous bloggers have been added to the center's database, said spokesman David Heller.

While courts often are inclined to protect anonymous speech, "plaintiffs still win these cases all the time," said Paul Levy, a lawyer for Public Citizen, a consumer watchdog. Even before a complaint is filed, an Internet service provider will often divulge an identity without hesitation.

Depending on the state, two basic standards seem to be evolving: One standard requires that the plaintiff has to show that there is a strong legal case to be made for defamation. Another, stricter standard imposed by other courts adds a balancing test to measure the impact of disclosure on both sides.

While the state's high court has yet to rule conclusively on the issue, individual courts in Pennsylvania "have recognized that there is at least some qualified right to speak anonymously and to overcome that right the potential plaintiff needs to make a substantial legal and factual showing that his case has merit," Mr. Levy said.

While courts seek clarity, digital rights advocates fear those efforts may be complicated if Congress revises the 1996 Telecommunications Act, which protects Internet service providers from these kinds of suits.

"With the issue of Internet anonymity bubbling up in courts and legislatures across the country, a showdown between reputation, privacy and safety interests on the one hand, and the First Amendment rights of message posters and online service providers on the other, is inevitable," says Robert D. Richards, director of the Pennsylvania Center for the First Amendment at Penn State University.

That particular federal telecommunications law doesn't affect anonymous bloggers directly -- just the websites providing them with a venue -- and was designed to encourage participation on fledgling Internet sites on the principle that "people shouldn't be responsible for content provided by others," said Daniel Solove, a George Washington University law professor.

He believes, however, that the federal law providing blanket immunity is overly broad.

If an Internet service provider "has reason to know something is defamatory or invasive of privacy, then one shouldn't be immune," Mr. Solove said, noting that he believes bloggers should get the same protections as journalists.

But "courts have become overzealous in interpreting [the Telecommunications Act] and have expanded it beyond its intended purpose," he added.

Others argue that John Doe subpoenas are little more than fishing expeditions by those wishing to silence their critics rather than proceed with a defamation suit, noted Sara Rose, a lawyer for the American Civil Liberties Union in Pittsburgh, who is representing Mr. Rattanni in the DeRosa case. Mr. DeRosa's lawyer couldn't be reached for comment.

"In the late '90s and early 2000s, we had a lot of situations where a lawyer would see something where an employee would post something about the company, file a lawsuit, find out the identity, fire them and drop the lawsuit," she said,

Taming anonymous Internet speech may produce another law, however: the one of unintended consequences.

In the New York model case, Google initially refused to reveal the anonymous speaker who had referred to the model, Liskula Cohen, as "psychotic," and as a prostitute. In August, a New York State Supreme Court Justice ordered Google to release the blogger's name -- another model -- claiming that "the thrust of the blog is that [Ms. Cohen] is a sexually promiscuous woman."

That ruling, in turn, has triggered numerous suits against Google by people who feel they were "cyber-smeared," some lawyers claim. And two months later, hackers attacked the Manhattan Supreme Court website and Google -- in what experts said appeared to be retaliation for the search engine giving up the name of the blogger.

That continued uncertainty is one reason some bloggers, like Bram Reichbaum, have thrown in the towel.

"I enjoyed peoples' ability to post anonymously," said Mr. Reichbaum, who closed down his political blog, The Pittsburgh Comet, in January. "It made for a more exciting website and a more informative one.

"Sometimes I'd receive a comment that was beyond the pale and I'd delete it when I saw it, but whenever a heated issue came up in the city, I was walking around with my BlackBerry and checking it every half hour to see what the comments were and what I needed to delete.

"In the end, it just became too time-consuming."

Doug Oster writes a blog, "Growing With Doug," exclusively at PG+, a members-only web site of the Pittsburgh Post-Gazette. Our introduction to PG+ gives you all the details.