A woman is asking a federal appeals court to reinstate a lawsuit accusing comedian Cosby of defaming her when his representative disputed a news story about her rape allegations. Picture: AP Photo/Matt Rourke, File

Boston - A lawyer for an actress who claims Bill Cosby raped her in 1974 told a U.S. appeals court on Wednesday that the comedian "destroyed" her reputation by calling her a liar after she came forward with her allegations in a 2014 newspaper interview.

Katherine McKee's lawyer made that claim as he urged the 1st U.S. Circuit Court of Appeals in Boston to revive a defamation lawsuit she filed against Cosby based on a letter his lawyer sent the New York Daily News after it published the interview.

"This case is about defamation and about restoring the good name and the good reputation of Kathy McKee, which was destroyed by Bill Cosby in a letter he had published to a newspaper," said William Salo, McKee's attorney.

Cosby's lawyer, Alan Greenberg, argued that the lawsuit was properly dismissed in February. He said McKee became a public figure when she gave the interview, which under the law means she needs to prove Cosby acted with malice.

"She put her credibility on the line by making these terrible accusations in the most public way," he said.

McKee is one of dozens of women who made allegations of sexual assault by Cosby going back decades, shattering his family-friendly reputation built upon a career highlighted by his role in the 1980s television comedy "The Cosby Show."

Most of the allegations are too old to be criminally prosecuted, though Cosby is awaiting an April retrial in Pennsylvania on charges he sexually assaulted a former basketball coach at his alma mater, Temple University.

Cosby, 80, has denied wrongdoing in all the cases, saying any encounters with his accusers were consensual.

McKee sued the entertainer in December 2015, a year after the Nevada resident told the newspaper that Cosby raped her in a Detroit hotel room in 1974.

She contended a letter a lawyer for Cosby sent the newspaper called her a liar by saying the article was "defamatory," characterising her claims as "wild" and suggesting she had a criminal record by pointing to other accusers' crimes.

During Thursday's hearing, judges peppered Salo with questions about whether McKee's case depended on whether she must prove malice.

U.S. Circuit Judge Sandra Lynch, meanwhile, asked why Cosby's lawyer in his letter felt it necessary to dive into the criminal backgrounds of other women while discussing McKee.

"Its sort of smearing her with mud by making a statement about other accusers," Lynch said.