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A federal appeals court refused Wednesday to revive a defamation lawsuit filed against Bill Cosby by a woman who said he raped her decades ago.

A three-judge panel of the 1st U.S. Circuit Court of Appeals in Boston upheld a lower court ruling dismissing Kathrine McKee's lawsuit against Cosby.

The former actress said Cosby defamed her in a letter that his lawyer sent to the New York Daily News demanding a retraction of a 2014 story about McKee's rape allegations. The judge who dismissed McKee's case said the letter was protected by the First Amendment.

McKee, who said Cosby raped her in a Detroit hotel room in 1974, was among dozens of women who came forward with allegations against the actor once known as "America's Dad" for his TV role as Dr. Cliff Huxtable. Cosby has denied all allegations of wrongdoing.

Alan Greenberg, an attorney for Cosby, said in an email that they are pleased with the appeals court's "well-reasoned decision confirming that there was no defamation."

An attorney for McKee did not immediately respond to an email on Wednesday.

McKee's lawyer argued earlier this month that McKee does not have to prove actual malice because she is not a public figure. To show actual malice, she would have to prove Cosby knew statements in the letter were false or entertained serious doubts as to whether they might be true.

But the appeals court said McKee became a public figure when she went public with the rape allegations in the newspaper.

"McKee took concerted steps meant to influence the public's perception of whether Cosby was, in fact, a sexual predator," Judge Sandra Lynch wrote for the panel.

A separate defamation lawsuit filed by seven other women also is pending in Massachusetts, where Cosby owns a home. The 80-year-old has filed a counter lawsuit accusing those women of defamation.

The only criminal case against Cosby ended in a mistrial in Pennsylvania in June. Cosby is expected to be retried in April on charges that he drugged and molested an employee of Temple University, his alma mater. Cosby insists their encounter was consensual.