Former Harvard law professor Alan Dershowitz is trying to block a Jeffrey Epstein accuser's attempt to analyze an audio recording of a call with David Boies, which could prove central to a contentious defamation case playing out in federal court.

Dershowitz's attorneys called the request to produce the analogue tape to third-party forensic firms a "wholly premature, if not improper" bid to access its contents ahead of discovery.

The microcassette recording allegedly includes a 2015 phone conversation between Dershowitz and  Boies, who until recently represented Virginia Giuffre in her defamation lawsuit against the retired professor.

Dershowitz maintains Boies, chairman of Boies Schiller Flexner, disparaged his own client's case on the call and expressed doubts about Giuffre's claims that she was trafficked by the late financier and forced to have sex with Dershowitz and other powerful men.

Many more women claimed they were trafficked by Epstein at his Palm Beach estate, in his Manhattan home and on his private Caribbean island after the #MeToo movement spread amid Hollywood scandals two years ago.

Dershowitz, who has repeatedly and forcefully denied sexual allegations tied to Epstein, made the substance of the conversation a key part of his defamation defense in the case, claiming Giuffre conspired with former attorneys to extort him with false allegations of forced sex.

U.S. District Judge Loretta A. Preska of the Southern District of New York last month ordered Dershowitz to provide forensic firm Stroz Friedberg with a digital recording of the call to make a copy for both sides.

Dershowitz turned over a microcassette, which is believed to hold the original audio of the conversation. No content from the tape have been made publicly available.

In a Nov. 1 letter, Giuffre's new attorney, Chuck Cooper, said the digital recording was only a "partial recording" with chunks of "either incomprehensible or wholly inaudible" dialogue.  The poor quality, he argued, raised "grave concerns" about the accuracy of a sealed transcript that Dershowitz previously provided to the court.

"Many of the words Mr. Dershowitz records in these transcripts simply cannot be discerned with any degree of confidence on the recording he provided," said Cooper, a conservative legal luminary and chairman of the Washington law firm Cooper & Kirk.

As a result, Cooper said "expert analysis of the microcassette is imperative" to determine the true contents of the conversation. But he said Stroz Friedberg lacked the ability to analyze analogue storage devices or extract the audio they hold and asked Preska for an order requiring Stroz to send the tape to forensic firms with the required sound capabilities.

On Monday, an attorney for Dershowitz said the request was simply a stab at "unilateral pre-answer discovery" and countered the microcassette should be returned to the defense.

"Plaintiff's contentions as to accuracy and audibility of the recording are issues for trial or to be explored during discovery," Aidala Bertuna & Kamins attorney Imran H. Ansari wrote in a two-page letter. "If and when Mr. Dershowitz seeks to admit the tape into evidence, it will be his burden to establish authenticity and audibility, and arguably, if he did not to seek its admission, further forensics would not be needed."

Ansari also raised concerns about potential damage to the tape if it was transferred "between multiple third parties."

The conversation has played an important role in the lawsuit, which accuses Dershowitz of defaming Giuffre in a series of public statements calling her a perjurer and a prostitute.

Dershowitz said he planned to call Boies and partner Sigrid McCawley as trial witnesses. And last month, Dershowitz succeeded in having Boies Schiller disqualified under the witness-advocate rule, which bars attorneys from participating in cases where other lawyers in their firm might be called as witnesses.

Giuffre hired Cooper to take over the case last week on Boies' recommendation. Boies and McCawley, longtime attorneys for Giuffre, both intend to continue to represent her in other matters.

In an interview, Boies disputed Dershowitz's characterization of their phone call and said the former professor was using only snippets of the recording to take the discussion out of context. He challenged Dershowitz and his team instead to make the full contents public and "let people decide for themselves" what actually was said.

"If Alan Dershowitz had a tape that was helpful to him, he would have made it public by now," he said.

Dershowitz was not available for comment by deadline, and Cooper did not return a call seeking comment on the latest court filings.

Epstein died by suicide Aug. 10 at a New York federal jail, but relatives are disputing the medical examiner's conclusion, pointing to homicide as a possibility. He was detained on sex-trafficking charges after avoiding federal prosecution in Florida in exchange for a Palm Beach County plea deal allowing him to stay out of jail for much of a lenient sentence.

The defamation case is Giuffre v. Dershowitz.

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