In recent weeks, efforts to resolve the thicket of legal actions have begun, but Mr. Dershowitz insists that any settlement must clear him of sexual wrongdoing. The woman accusing Mr. Dershowitz has not filed a complaint with the authorities or a lawsuit against him. Instead, her allegation first emerged in a lawsuit that challenged Mr. Epstein’s plea agreement.

Mr. Dershowitz long taught his students that everyone, even those charged with the most heinous crimes, deserves a defense. But he now says he hesitated when Mr. Epstein called him in 2006 to ask for help because he was being investigated in connection with sex crimes.

“I said, ‘Look, you know Jeffrey, we’re acquaintances, maybe that’s not such a great idea,” Mr. Dershowitz said. “He said, ‘No, no, no, I really need you to do this.’”

The case, Mr. Dershowitz realized, “was right in my wheelhouse.”

In December 2005, a few months before he got that phone call, Mr. Dershowitz, his wife, children and grandchildren were vacationing at Mr. Epstein’s Palm Beach mansion.

The friendship between the men started in the mid-1990s on Martha’s Vineyard. Not long after they met, Mr. Epstein invited Mr. Dershowitz to a birthday party for Mr. Wexner. Instead of accepting presents, the retail magnate had a tradition of asking friends to bring the most interesting person they had met over the last year.

“He said, ‘I’d like to bring you,’” Mr. Dershowitz said.

By any measure, Mr. Dershowitz had led an interesting life. At 28, after clerking for a Supreme Court justice, Mr. Dershowitz became the youngest professor ever hired by Harvard Law School. It was outside the classroom, however, where his fame grew. He handled celebrated cases, appeared as television commentator and wrote many books, fiction and nonfiction. His account of the von Bulow case, “Reversal of Fortune,” was made into a film in 1990 in which the actor Ron Silver donned a bushy mustache and aviator glasses to play Mr. Dershowitz.

Along with enjoying celebrity, Mr. Dershowitz has also relished excoriating those he considers foes. He has taken on journalists, chided universities for coddling students and has been relentless in his defense of Israel, for example, accusing the writer Alice Walker of bigotry for refusing to allow an Israeli publisher to translate her novel “The Color Purple.”