If any single case transformed Alan Dershowitz into a celebrity lawyer and household word, it was his defense of Claus von Bulow. And the von Bulow case remains the clearest demonstration for many of Dershowitz's critics of his unflagging thirst for public exposure, and the risk that may pose to his clients.

Dershowitz won a spectacular victory in the case, essentially by persuading the Rhode Island Supreme Court that von Bulow had been deprived of evidence critical to defending himself against the charge that he had twice tried to murder his wife with injections of insulin. After von Bulow was acquitted at a second trial, Dershowitz wrote a book, "Reversal of Fortune," about the case.

Von Bulow's stepchildren then tried to use the book in their $56 million civil suit against their stepfather, claiming that because he had authorized its publication, the book waived his right to keep private all his past conversations with defense lawyers. Because the matter was decided in favor of von Bulow and Dershowitz, Dershowitz dismisses the whole affair as an all's-well-that-ends-well chapter of his career. Von Bulow, he says, "pleaded with me, over and over again, to do my book... . There's just no way you can betray a client when he wants you to do it."

But according to some lawyers and legal ethics experts, the mere fact that it was the source of troublesome and costly litigation for his client suggests that it was unethical for Dershowitz to publish, with or without consent.

Harold R. Tyler Jr., the former federal judge who represented von Bulow in the civil suit, says Dershowitz never advised his client of the potential risk involved. "This put von Bulow in a terrible spot," he says. He calls the act of writing the book under those circumstances "unconscionable."

Yale Law School Prof. Geoffrey Hazard, a leading legal ethics expert, says, "I don't understand what benefit redounds to Mr. von Bulow" from publication. "I do understand that considerable benefit could redound to Dershowitz, and in that sense, I think it's conflict of interest, even if the client consented."

At least the book portrayed von Bulow as an innocent man. The movie, in which Claus is played with creepy verve by Jeremy Irons, is a different story. While it halfheartedly argues von Bulow's legal innocence, it makes a chilling case that he was at least morally culpable in his wife's death, for assisting in a passive suicide. The moviemakers even offer, as one possible version of Sunny von Bulow's fate, a scene showing Claus dragging his wife, insensate from self-administered doses of alcohol and drugs, to an open window, in hopes of hastening her death.

The Dershowitz character himself delivers the coup de gra~ce, telling his client after the appeal succeeds, "Legally, this was an important victory. Morally, you're on your own."

In addition, Dershowitz is shown confronting von Bulow with the suggestion that he committed necrophilia on the body of his mother -- a discussion that never took place about an incident von Bulow adamantly denies. Von Bulow, who called the scene "defamatory filth" in a letter to Dershowitz, has taken legal action to have the scene excised when the movie is released in other markets.

Dershowitz points out that he signed over the rights to his book, retaining no creative control over the script; much of the material harmful to his client, he says, was drawn from the deposition von Bulow gave in the civil trial, a matter of public record.

But the average moviegoer is likely to conclude that "Reversal of Fortune" carries Dershowitz's imprimatur and relates his understanding of the truth. His son Elon was a co-producer and consulted Dershowitz often. And Dershowitz has helped promote the movie.

Dershowitz believes that "on balance" the movie has been good for von Bulow. "A lot of people," he says, "thought it was a very, very strong positive for his image."