Are Twitter messages a stream of opinion and hyperbole that shouldn’t be taken seriously, or a serious form of communication that can expose users to defamation and libel claims?

That debate is starting to play out in the court system, where a small but growing number of lawsuits have been filed against Twitter users by those claiming to have been libeled or defamed by so-called “tweets” — the 140-character messages that users send to their followers.

Twitter advocates won an early victory last week when a Cook Country, Ill., circuit judge dismissed a defamation suit filed by a Chicago-area real estate management company against a former tenant who tweeted about mold in her apartment. News of the suit went viral on blogs and Twitter as social media users considered the potential ramifications.

Attorneys at The John Marshall Law School’s Center for Information Technology and Privacy Law represented 25-year-old defendant Amanda Bonnen against the lawsuit filed by Horizon Group Management.

“I think this emphasizes that defamation fits a particular standard, and the medium doesn’t matter,” said center director Leslie Ann Reis, a member of Bonnen’s pro bono legal team.

Judge Diane J. Larsen issued no written opinion but indicated in court that the complaint against Bonnen was too vague, Reis said.

Horizon filed suit against Bonnen in July seeking more than $50,000 in damages. The complaint cited a tweet dated May 12 on Bonnen’s Twitter account that read: “Who said sleeping in a moldy apartment was bad for you? Horizon realty thinks it’s okay.”

The complaint called the tweet “false and defamatory.”

Bonnen’s defense team responded that the tweet in question didn’t meet the Illinois standard for defamation on numerous grounds, including that tweets are considered opinion in the social context and that the message lacked factual context and verifiable facts. The motion to dismiss cited a 2009 study of Twitter in which more than 40 percent of tweets were found to be “pointless babble.” It noted that many of the other tweets Bonnen wrote at around the same time were clearly opinion or exaggerations.

“When one considers Ms. Bonnen’s allegedly defamatory tweet in the social context and setting in which the statement was published, its nature as rhetorical hyperbole is readily apparent,” the motion said.

Horizon responded that Twitter content isn’t mere drivel, but rather a “legitimate medium used by reporters to report up-to-the-minute updates on legal actions, by rabbis, by people to support specific causes or engage in a certain activity, and as a marketing tool.” The U.S. Centers for Disease Control and Prevention, for example, uses Twitter to disseminate information, the company argued. Tweets, it said, should be treated no differently than other forms of publication.

“They did a good job of laying out the argument that these tweets aren’t serious,” said Bret A. Rappaport, the attorney with Hardt Stern & Kayne of Riverwoods, Ill., who represented Horizon. “Our position is that it’s text and it doesn’t matter if it’s a book or a billboard.”

Rappaport said that he and his client were considering their options in the case.

Other high-profile Twitter defamation cases are pending. For example, a clothing designer sued rock star Courtney Love in Los Angeles County, Calif., Superior Court in March alleging defamation, invasion of privacy and infliction of emotional distress because of a series of unflattering tweets that Love wrote about her. A judge declined to throw out the suit in October.

Reality television star Kim Kardashian was sued in December by a Miami doctor who markets a cookie weight loss diet. Kardashian wrote two tweets denying that she was on “Dr. [Sanford] Siegal’s Cookie Diet” and referring to the program as “unhealthy.” The case is pending.

The dismissal of the defamation suit against Bonnen doesn’t mean that tweeting can’t be defamatory, warned Richard Balough, who was one of the attorneys representing her.

“Just because you are doing something in 140 characters doesn’t mean there can’t be libel or defamation,” Balough said. “People always need to exercise caution, regardless of whether they are tweeting, talking or writing an e-mail.”

Karen Sloan is a reporter for The National Law Journal, a Legal affiliate based in New York. •