NEW YORK — Katie Allison Granju, who writes a blog on parenting and current events, was worried a barbed post could get her sued. So she bought media liability insurance to protect her home and savings.

"You wouldn't publish a newspaper without liability insurance, so you should take the same precautions with blogging, if you have any kind of audience or readership," said Granju, 41, of Knoxville, Tenn.

U.S. lawsuits over Web postings jumped 70 percent in 2008 from 2006, when the social networking site Facebook Inc. was opened to anyone with a valid e-mail address and Twitter Inc. was first started. The data come from the Citizen Media Project, which is affiliated with Harvard Law School's Berkman Center for Internet & Society in Cambridge, Mass.

The cost of defending against legal action can range from $5,000 to at least $100,000 if the case goes to trial, said Ron Coleman, a trademark lawyer at Goetz Fitzpatrick in New York. Of the 256 lawsuits dating as early as 1994 through April tracked by the New York-based Media Law Resource Center, damages were awarded in 17 cases, totaling $43.9 million.

Blog posts and comments on sites such as Facebook, News Corp.'s MySpace and Twitter are often written quickly and informally, said Kim Isbell, a staff attorney at the Citizen Media Law Project. They can also be stored indefinitely and may be taken out of context, so social media may lead to more liability issues than traditional print, Isbell said.

Social networking sites are used by 46 percent of adult Internet users compared with 29 percent a year earlier, according to an April survey by the Pew Internet & American Life Project in Washington.

"There are more people online and more tools available to monitor what's being said online — so you have more fish and more nets," said Robert Cox, president of the New Rochelle, N.Y.-based Media Bloggers Association, which provides legal support to bloggers. Cox faced legal action by the New York Times Co. in 2004 for his blog that parodied the newspaper's correction policy.

Wealthy online users are more vulnerable to being sued, especially amid a struggling economy, said Bill Densmore, director of the Media Giraffe Project at the University of Massachusetts-Amherst.

Most Web-related lawsuits center on claims of defamation or copyright infringement. Seventy-six of the lawsuits followed by the Media Law Resource Center were related to libel, a written fact that injures someone. As an example, a Chicago tenant was sued by a management company in July for complaining about her allegedly mold-infested apartment via Twitter.

Singer Courtney Love was sued earlier this year in California for Tweets about fashion designer Dawn Simorangkir that Simorangkir claims are false and defamatory. Love Tweeted that Simorangkir sold drugs, had a record of prostitution and was an unfit parent, according to the complaint. Love filed papers asking the court to throw out the complaint and the suit is pending.

A 31-year-old blogger in New York, Adam Robb Rucinsky, received a cease-and-desist letter in April for his mocking of Danyelle Freeman, the former restaurant critic for the New York Daily News. He said he would never buy blog insurance and continues his posts.

"I would worry possessing insurance would only serve to put a price on my head," Rucinsky said.

Some bloggers may be covered for online lawsuits under the personal liability coverage of their homeowners or renters insurance policies. MetLife Auto & Home, a unit of New York-based MetLife Inc., and Chubb Corp. in Warren, N.J., include coverage for damages caused online.

Separate media liability insurance is an option for bloggers who make money.

Bloggers should expect to pay from $500 to $1,000 annually for $300,000 of coverage a year on average, said Cox of the Media Bloggers group.