• by Wendy Davis  @wendyndavis, January 5, 2010

The doctor behind the Cookie Diet has sued celebrity Kim Kardashian for allegedly defaming him in on Twitter.

The reality TV star allegedly tweeted in October that Dr. Sanford Siegal was "falsely promoting" that she was on the cookie diet. "Not true! I would never do this unhealthy diet! I do QuickTrim!," she allegedly said via Twitter. "If this Dr. Siegal is lying about me being on this diet, what else are they lying about? Not cool!"

In a lawsuit filed last week in state court in Florida, Siegal alleges that these statements are false and defamatory. The diet doctor also alleges that Kardashian -- who reportedly earns $10,000 per tweet as an endorser -- was on QuickTrim's payroll at the time.

Kardashian's alleged tweet about Siegal "lying" appears to stem from an article that was linked to from CookieDiet.com. That piece -- authored by a news outlet with no connection to Siegal -- named Kardashian as one of several celebrities who had lost weight on the diet.

Last month, Kardashian sent Siegal a cease-and-desist demanding that he remove the link -- which he did, according to his court papers.

It's not clear that Kardashian's alleged statements about the diet being unealthy, or about Siegal "lying" regarding Kardashian's use of products, are libelous. For one thing, Kardashian's alleged statement that the diet is "unhealthy" might be viewed as an opinion, and only statements of facts can be libelous. In addition, the alleged statement that Siegal was "lying" about Kardashian might not be the type of remark that's likely to damage Siegal's reputation.

Regardless of whether Siegal can prove libel, the allegations in the case highlight some of the issues the Federal Trade Commission aimed to address with its new blogger rules. The FTC's new guides, which took effect Dec. 1 (after the alleged Kardashian tweets), state that bloggers should disclose all material connections between themselves and companies whose products they write about.

Kardashian allegedly touted QuickTrim while disparaging the Cookie Diet without disclosing that QuickTrim was paying her, according to Siegal's lawsuit.

But Siegal himself allegedly linked to an article that contained untrue information. Some government agencies might view that link as an endorsement of the article's content, said Eric Goldman, director of the High Tech Law Center at Santa Clara. In late 2008, the Securities and Exchange Commission said in proposed new guidance that companies could be liable for fraud if they link to material created by other publishers that contains false information -- even though the federal Communications Decency Act says sites are immune from liability for material created by third parties.

Despite the SEC guidance, Goldman says it's not at all clear that either courts or government agencies would view the links to news articles on CookieDiet.com as problematic. "We don't know the answer to the simple question: Are you endorsing content by linking to it?"