Michael Patrick Leahy, author and founder of "Top Conservatives On Twitter," filed a lawsuit against blogger Stephanie Grasmick, Twitter user "Duke St. Journal," and 25 anonymous Twitter users for libel, false light invasion of privacy, intentional infliction of emotional distress, and tortious interference with contract.

Leahy, who appears to be handling the case himself, asserts that Grasmick posts on Twitter under the name StephanieInCA and is the operator of Teablogging, a site created "to chronicle the lead-up to the April 15 conservative hysteria Tax Day Tea Parties and to serve as a central repository for low-brow teabag-related sex jokes." His four-count complaint alleges, among other things, that Grasmick libeled him in a blog post on May 13, 2009, in which she falsely stated the he is:

• a "major tax fraud";
• a "delusional profiteering creep";
• an "insane clown"; and
• a "member of some alien race of Lizard People."

Compl. (First Cause of Action) ¶¶ 1-5.  Leahy also claims that Grasmick and Duke St. Journal repeated these false statements on Twitter.

Leahy also asserts a claim for false light invasion of privacy, although the conduct he complains about is more properly characterized as a claim for publication of private facts: the disclosure of his "residence in Williamson County, Tennessee."  Compl. (Second Cause of Action) ¶ 1. 

In addition to monetary damages, Leahy claims he is "entitled to see the complete records of all Facebook communications and telephonic commuications between Grasmick and her 283 Facebook friends, as well as public and private messages sent by Grasmick to those 469 persons she follows on Twitter, in order to determine the identity, if there is such, of any additional defendants who should be named in this complaint."  Compl. ¶ 18.

Update: 

May 22, 2009: Dispute resolved by mutual accord.  Leahy reported on his blog that "Grasmick has agreed to remove the false and misleading word from the headline of her May 13, 2009 blogpost which caused me to file a libel suit against her on May 18, 2009. I, in response, have withdrawn my complaint against her."  Grasmick confirmed the agreement and removed the word "fraud" from her previous blog post.

Digital Broadband Networks and its president Patrick Lim sued seven pseudonymous internet posters in New Jersey state court for defamation over statements on electronic bulletin boards dedicated to Digital Broadband on Ragingbull.com and on general messages boards on Yahoo. The company alleged that the purpose of the postings was to drive its stock price down in order to reap profits through short selling.

Digital Broadband filed a motion for permission to engage in pre-litigation discovery to uncover the identities of the anonymous posters.  In a March 2004 hearing, the trial court granted the motion, allowing the company to subpoena Yahoo! and Lycos, the operator of the Raging Bull forum.  

One of the posters, "pseeker," filed a motion for permission to take an immediate appeal to the Superior Court of New Jersey, Appellate Division, in order to prevent the disclosure of his/her identity. Public Citizen's Litigation Group filed a brief supporting pseeker's right to appeal. The record is not clear about the result of this motion or what, if anything, happened after the appeal. 

On July 14, 2008, Ecommerce Innovations filed a suit in the Central District of California against several Does alleging defamation and trade libel for posts on Ripoff Report, a website that allows users to post reports about individuals and companies that they believe have "ripped them off" or treated them unfairly.  After filing suit, Ecommerce served a subpoena on Xcentric Ventures, LLC, the operator of Ripoff Report, seeking the identities of the anonymous posters.  Counsel for Xcentric objected to the subpoena, and Ecommerce filed a motion in federal district court in Arizona, seeking to compel Xcentric to produce the requested information.

The district court ordered Xcentric to complay with the subpoena.  In its ruling, the court held that Ecommerce was required to present evidence sufficient to survive a motion for summary judgment for those elements of its defamation or trade libel claim that were not dependent upon knowing the identity of the anonymous poster. The court analyzed five specific allegedly defamatory statements and concluded that Ecommerce had presented evidence sufficient to survive summary judgment with respect to one of the statements.

Xcentric moved to stay the order pending appeal to the Ninth Circuit, and the district court granted the stay, finding that the question of what standard to apply before ordering disclosure of anonymous Internet posters was significant and unanswered by the Ninth Circuit.  The court also found that Xcentric could face serious hardship because "[o]nce the identity of the anonymous poster is revealed, relief from the Ninth Circuit will no longer be available to Xcentric."

Xcentric filed a notice of appeal on March 6, 2009.  According to the docketing statement, the issues on appeal are as follows: "(1)Whether, in light of the First Amendment's protection of anonymous speech, the District Court applied the correct standard for a subpoena seeking to obtain the identity of an anonymous author; and (2) whether the District Court erred in finding that Plaintiff/Appellee met its burden of presenting evidence sufficient to overcome the First Amendment rights of the anonymous author?"

On May 16, 2002, Equidyne Corporation, a medical device company, sued twenty-one John Doe defendants (identified by pseudonyms) who posted statements about the company on the Yahoo! and Lycos financial message boards. Equidyne claimed that the defendants were current or former employees, that they signed confidentiality agreements, and that their postings to the websites violated their confidentiality agreements.  Equidyne also argued that the postings violated federal securities laws.

Equidyne obtained permission of the court to subpoena Yahoo and Lycos to obtain information that would identify who used the twenty-one pseudonyms.  Lycos identified five defendants.  Three of these defendants, including Henry Rhodes, moved to dismiss the complaint. Equidyne voluntarily dismissed its complaint against two of the defendants, but not Rhodes. The court ultimately granted Rhodes' motion to dismiss for improper venue.

Yahoo provided notice of the subpoena to its relevant subscribers by email.  One such defendant, going by the moniker Aeschylus_2000, filed a motion to quash the subpoena, invoking the First Amendment right to speak anonymously.  According to CyberSLAPP, the district judge applied the standard from Dendrite v. Doe and found that Equidyne had shown a prima facie case under federal securities laws and denied the motion to quash.  The court also denied a motion to reargue.  Aeschylus appealed to the Third Circuit arguing that the district court judge misapplied the Dendrite standard.

The case appears to have settled while on appeal.