CAMBRIDGE, MASS. -- It was inevitable: America's most notorious criminal defendant finds America's most famous law professor.

No, the prospective client is not Claus von Bulow, the stiff-necked socialite acquitted of twice trying to murder his wife; not famously unlikable hotel queen and tax cheat Leona Helmsley; not Green Beret doctor Jeffrey R. MacDonald, convicted of bludgeoning and stabbing to death his pregnant wife and two daughters; not fallen evangelist Jim Bakker, convicted of bilking hundreds of followers of millions of dollars; not spy Jonathan Jay Pollard, convicted of selling American military secrets to the Israelis; not Jack Henry Abbott, the prison author who won a second chance at freedom and used it to knife a man to death -- though these are all people represented by Harvard Law School professor Alan Dershowitz, now or in the past.

This would-be client recently approached Dershowitz, as so many do, through the huge volume of mail that comes to his office from prisoners who read him in Penthouse, or who see him on television, or who one day wake up knowing about him through the strange osmosis that is fame in America.

Like most of Dershowitz's clients, this one has already been found guilty as charged, and Dershowitz does not yet know whether there are promising grounds for appeal. In fact, he knows almost nothing about the case, except that it involves rape and that it burned a name into the national consciousness. But when he got the neatly typed one-page letter, he immediately decided to take the case if he could find any grounds at all. He's having it researched.

He says notoriety alone would never lure him to a case. He says he chooses only those clients who offer him the chance to right a grievous wrong or uphold a hallowed principle of democracy. All his instincts, he says, inform him that this is such a case.

Alan Dershowitz, meet Willie Horton.

The Willie Hortons of the world know Alan Morton Dershowitz as "the lawyer of last resort," a label bestowed long ago by some talk show producer or magazine writer and repeated by all the producers and writers since. "It sounds like a weird title," says Dershowitz, "but it's really true. I hear from people who have nowhere else to turn."

At 52, he is one of the best-known appellate attorneys in the country -- a brilliant, indefatigable strategist, a man who has raised to hardball science the techniques of adversarial justice, in which truth and legally provable truth are often different matters.

But Dershowitz is something more than a legal cowboy. He combines the prestige of the Harvard professor with a gift for punchy expression and an endless readiness to deliver it to the media. To both of these he adds a belief in the scorched-earth practice of law, that it is nothing more or less than his job to do everything within the bounds of legality to advance his client's case.

Respectability, publicity, ruthlessness. No other lawyer in America so successfully combines all three. F. Lee Bailey and Marvin Mitchelson achieved the second and third, but at the expense of the first. Iran-contra counsel Arthur Liman's reputation concedes him the first and second, but not the third. Brendan V. Sullivan, Oliver North's pit-bull lawyer, has the first and third, but avoids the second.

A triple threat, Dershowitz has acquired a unique clout in the American legal system. In the popular imagination, he embodies some of the brightest potential of the law and some of its worst tendencies to elevate sophistry and technicality over justice. His career is a multilayered lesson in manipulation -- the manipulation a lawyer performs upon the facts, upon the courts, and upon the court of public opinion that is Alan Dershowitz's special field of expertise.

In that court, Dershowitz has devoted considerable energy to promoting his legend. He has posed in his sauna for People. He recently graced the cover of New York magazine holding the hand of Helmsley. He has appeared on "Nightline" roughly two dozen times since the show's debut 10 years ago. He has "three college students who do nothing but read and brief me on my mail," he says.

Most recently, Dershowitz has been heroically portrayed in the movie "Reversal of Fortune." Based on Dershowitz's book about his successful appeal of von Bulow's first trial, and co-produced by Dershowitz's son Elon, the movie depicts him as a hotblooded idealist. This Dershowitz, played by Ron Silver, will take only cases that pose issues of enormous constitutional import, or the cases of destitute souls being ground under the boot heel of an indifferent Justice. "I'm not a hired gun," he tells von Bulow. "I've got to feel there's some moral or constitutional issue at stake."

The movie offers a subplot to cement Dershowitz's credentials as a crusader for justice. His representation of the deeply unsympathetic von Bulow character is mitigated, in dramatic terms, by the lawyer's passionate dedication to "the Johnson brothers," two innocent young blacks on Alabama's Death Row. They helped their dad escape from prison, the movie explains, and are now being wrongfully held to account for a murder the father later committed.

Like much of the movie, the Johnsons have real-life counterparts. Except the Tison brothers are imprisoned in Arizona. And they not only freed their father, already a convicted killer; they also freed another murderer, arming both men with guns. They were present when the escaped convicts, in need of a getaway car, blew away a family of four in the wastes of an Arizona Indian reservation.

And there is another discrepancy, which in a sense is quite minor, a filmmaker's fib -- one that wasn't Dershowitz's idea, but that he defends. In another sense, however, it is an instructive measure of how far Dershowitz is willing to cooperate in the manipulation of facts in order to burnish his own legend. In this sense, it is the mirror image of George Bush's cynicism in using Willie Horton to scare white America.

The other discrepancy between film and fact is that Ricky and Raymond Tison are white.

Different Worlds For all his public exposure, the world of Alan Dershowitz is not an easy one to enter. There is a broad gulf between the caricature Dershowitz has made of himself in the public arena and the slight, wary man who runs his universe from behind a barricade of books and papers in a third-floor office at Harvard's Griswold Hall. "He's an exhibitionist," says Jeffrey Leeds, a former student who admires Dershowitz. "But like most exhibitionists, he doesn't really want people to know him."

He is a man so powerful he can command a hearing on the evening news or in the nation's biggest newspapers for a client already tried and convicted, yet so petty that even mild criticism reduces him to fits of Rumpelstiltskinian pique. And he appears to nurse -- even cling to -- a conviction that he is a victim of widespread cultural prejudice against Jews.

Dershowitz's style has thrust him into angry, inconclusive public confrontations with judges, prosecutors, politicians -- almost anyone who stumbles into the cross hairs of his triple-barreled shotgun.

The mere mention of his name elicits groans from any number of attorneys chagrined at the idea that Dershowitz is permanently etched into the public consciousness as the real-life model of a criminal defense lawyer.

And Dershowitz has earned such vocal enemies as Manhattan lawyer Michael Armstrong, a former federal prosecutor who debated Dershowitz recently at Fordham Law School in Manhattan, in a name-calling encounter the New York Times described as a "jai-alai match of the New York bar." Armstrong, who represented von Bulow's stepchildren in a civil suit against him, says of Dershowitz: "He really has the worst reputation in the profession of anybody I know who purports to have a reputation. ... Of course, he will ascribe that to the fact that he is a fighter against injustice, and has antagonized too many of the old-boy class."

Dershowitz replies that Armstrong is a prime example of that breed, bent on smearing the reputation of a challenger. "If I had the reputation that Armstrong wishes I had," he says, "I wouldn't have the clients Armstrong is jealous of."

Dershowitz, a master of high dudgeon, is at his happiest when in the middle of fights like this one. And this is the center of the puzzle that is Alan Dershowitz, a handsomely paid and influential man who has spent his career excelling in the nation's most august legal institutions, yet whose main precept of self-definition is that he is forever a member of the excluded classes.

Of Tactics and Ethics As a teacher he has some of the same antic energy he brings to arguing issues on "Geraldo," bobbing at the knees, juggling the chalk in his hand, pantomiming the various hypothetical situations he throws at the 50 or so students ranged around the room. He sports the olive-brown-black-tan color scheme, the wool sweater vest and comfy crepe-soled shoes of the liberal professoriate.

At this second-to-last meeting of his third-year course in legal tactics and ethics, he sketches the simple diagram that captures the essence of this course. Moving to the blackboard, he draws two vertical lines in chalk, marking the left one "E," for ethics, and the right one "T," for tactics. The left-hand line represents the scale of a lawyer's possible ethical standards, from 1 to 5 (1 being least ethical, 5 being most); the right-hand line stands for the possible range of tactics, up to the hardball maneuvers -- say, badgering a rape victim about her sexual history -- represented by "T-5." Tactics and ethics form, in his view, the pivotal trade-off facing any criminal lawyer, and therefore any client in search of a lawyer.

"Very often," Dershowitz tells his students, "if you want a T-5 you're going to have to go to an E-3. If you want an E-4, sometimes you're going to have to settle for a T-2."

Alan Dershowitz is proud to say he is an E-1, at least in any case where that is the price of achieving T-5. The pattern began in his very first criminal case, in 1972 -- one of the few cases in which he defended his client at trial, rather than on appeal. The accused was Sheldon Seigel, a Jewish Defense League member involved in bombing the office of impresario Sol Hurok. A woman was killed. Seigel admitted that he had made the bomb. But he was also, Dershowitz learned, a government informer, and unbeknown to the police had taped most of his conversations with the officer to whom he passed information about the JDL.

Seigel claimed that police had coerced his cooperation and promised him he would never have to testify. But he did not have tapes of the conversations to support that. At a pretrial hearing, Dershowitz worked around this gap in his cross-examination of the officer, reading first from transcripts of tapes he did have -- evidence the officer could contradict only at risk of perjury -- and going on to "read" passages supporting Seigel's claims. The officer, not realizing the trick and assuming Dershowitz must be reading his own words, confirmed them.

When the judge discovered Dershowitz's ruse he called it "reprehensible," and admonished the lawyer, "You and I ... sir, have two different ideas of the level at which one practices law." But in part because of the maneuver, Seigel was never tried, nor were his two codefendants, who couldn't be convicted without his testimony.

Tactics, 5. Ethics, 1.

Dershowitz stresses that "an E-1 is still legal, still ethical." And he is talking, he adds, only about professional ethics. Outside his work life, "what I urge people to be, and I hope I am, is E-5 in terms of personal ethics."

His professional life features three kinds of cases. One category is pro bono work, work done for free, including everything from the appeals of the Tison brothers to the case of a mentally ill woman who was committed against her will.

"I'm the only lawyer in America who has a rule that 50 percent of my cases are pro bono, always," Dershowitz says. While this remark might irk the thousands of public defenders, legal aid lawyers and civil rights lawyers making do on something less than the $400-or-so hourly fee he charges the paying customers, or the $100,000-plus he makes each year from Harvard, the fact remains that he gives his time freely to causes that seize his interest. He has worked tirelessly for Jewish causes and clients, notably Soviet dissident Natan Sharansky, whom he represented before a Soviet court.

In a second category of cases are the ones that have endowed Dershowitz with their own fame: the Helmsleys and von Bulows, MacDonalds and Bakkers.

Dershowitz shrugs off as sour grapes his detractors' suggestion that he is a "celebrity lawyer" bent on generating publicity for himself.

"For every Helmsley and von Bulow that I take," he says, "I turn down an equally glamorous and famous client." A seductive pause. "Tragically, I can't tell you who they are."

What unites all his clients, he says, is that something about their treatment by "the system" makes him mad. "The major criterion for me taking a case is, 'Have I gotten pissed off at something or somebody?' " Pissed off at the length of Bakker's 45-year sentence, imposed by the same judge who earlier hit another Dershowitz client with 25 years in a pornography case. Pissed off at what he sees as the underlying sexism in the prosecution of Helmsley, who he says never would have been sentenced to four years were she "a quiet, wifely, subdued woman." Pissed off that Pollard "was treated differently because he was a Jew spying for Israel." In the case of Willie Horton, "I am pissed that George Bush got elected president by focusing on the case of a man in prison, and by focusing on him because of his race."

And then there is a third category of cases Dershowitz takes, beyond the personal causes and the glamorously guilty. These are paying cases that are harder to learn about, for they are seldom promoted as part of the Dershowitz legend. This docket seems, for a Harvard professor, distinctly low-rent: Money laundering and cocaine distribution. Conspiracy to smuggle 36,000 pounds of hashish from Lebanon. A scheme by a personal-injury lawyer to submit fraudulent medical bills to insurance companies. A conspiracy by organized-crime figures to extort money from vending machine companies. A racketeering conspiracy involving a loan shark who punched a debtor who failed to pay up. Conspiracy to murder a government witness. An organized-crime effort to infiltrate the New York waterfront.

The legal and constitutional issues these cases raised were largely the familiar bread-and-butter arguments of criminal appeals -- the sufficiency of the evidence, for example, or the propriety of the jury instructions -- rather than issues that will rewrite the casebooks.

Asked about these, Dershowitz says they too are the kind of cases that demand the attention of an Alan Dershowitz. "Every good civil liberties lawyer today feels the need to get involved in mob cases, drug cases, rape cases, molestation cases -- those where the courts would be tempted to take shortcuts."

But in the next breath, he is once again the Harvard professor, taking care to distance himself from such clients. Often, he stresses, he never meets them. "I get the papers, I write the brief, I argue the case. I have no relationship with the client at all, often."

The Boy Before Harvard To enter his office, you pass through a door covered with the emblems of his estrangement: the singed Israeli flag sent by some antisemitic goon, the letters of a dozen or so more. "You filthy {expletive} Jew Boy," says a Christmas card. "JEWS ARE YOUR ENEMIES COCKROACHES AND PARASITES! WAKE UP AMERICA!" says one letter, in the all-caps addlement of the passionately disturbed. "Die Jew," instructs another.

Dershowitz proffers a nervous, rectangular smile and a cup of some politically correct tea -- free of caffeine, full of floating barklike bits. Behind him, the top several bookshelves are devoted to multiple copies of his own books: "Reversal of Fortune," "The Best Defense," which relates a series of his cases, and "Taking Liberties," a collection of his columns. Just behind his desk is a souvenir from the production of "Reversal of Fortune," a clapper saying "Scene 175X, Take 2."

He has been here for 26 years. According to his friend Jeanne Baker, part of his contentment at Harvard is its fulfillment of his desire "to have an institution to rail against, and to be an outsider vis-a-vis."

He started life, he makes clear, on the outside: growing up Orthodox in Brooklyn's Borough Park, an enclave of Jewish immigrants where many of his neighbors bore tattooed reminders of Hitler's brutality. He takes pride in an unpromising youth, full of bad grades and rough discipline from administrators at yeshiva. His mother, Claire Dershowitz, confirms his lack of early promise. "I'm surprised myself at the way he turned out," she says.

It was his mother who filled out his application to Brooklyn College, where he performed a dramatic turnaround. Deciding on law, he became a dedicated student and moved on to Yale Law School, where he edited the Law Review. After graduation he clerked in federal appeals court in Washington for Judge David L. Bazelon and then for Supreme Court Justice Arthur Goldberg. Harvard hired him at the age of 25, and at 28 he became the youngest tenured professor in the law school's history.

Along the way he married a high school sweetheart whom he met at an Orthodox summer camp; his brother, Nathan, married her sister. After Alan and Sue Dershowitz were divorced in the mid-'70s, he won custody of their two adolescent sons. Since then he has remarried, to a neuropsychologist, and now has a year-old daughter.

Even after he found his calling, he retained the idea of himself as the renegade. As he told People magazine, "I'm a post-Holocaust Jew. I have a little bit of a chip on my shoulder. Every outsider does." Even the working title of his next book bristles with that sensibility: "Chutzpah: Reflections of a Proud and Assertive Jewish American."

His friends think of his combativeness as the fruit of an unflinching intellectual honesty. "There isn't any group that Alan is involved with, or any person he's involved with, whom he would not oppose under the right circumstances," says Harvey Silverglate, his good friend and frequent co-counsel.

And oppose he does -- more than once choosing a public fight that grinds a personal ax. The adversarial, take-no-prisoners ethic of the courtroom -- the E-1, T-5 paradigm -- applies to other aspects of his public life. Perhaps the best example is the 1989 nomination to the 2nd U.S. Circuit Court of Appeals of U.S. District Judge John Walker -- first cousin to President George Herbert Walker Bush. Dershowitz launched a one-man campaign to stop the nomination, deriding "Cousin Johnny" as a "mediocre attorney" with a "lackluster career." He contended that the appointment violated federal anti-nepotism law and asked to testify against Walker before the Senate Judiciary Committee -- a forum easy to come by for a Harvard Law School professor.

While his objections were couched in high-minded appeals to judicial sanctity, Dershowitz also had a personal history with Walker. The judge had presided over a $56 million civil suit filed against von Bulow by his stepchildren, after his acquittal. Walker ruled that publication of "Reversal of Fortune" had waived the confidentiality of von Bulow's conversations with all of his attorneys -- meaning that the secrets of his defense would now be open to examination by his stepchildren's lawyers. Although the ruling was later overturned by an appeals court, Dershowitz's enemies chortled at the time that his lust for publicity may have lured him into a serious ethical lapse.

Thus, many observers suspected an element of payback when Dershowitz made a mission of opposing the Walker nomination -- especially when he accused the judge of unethical conduct. According to Dershowitz, Walker had confided to attorney Armstrong during the von Bulow litigation that he was looking forward to giving Dershowitz a hard time.

Armstrong denied the incident, as did Walker. "It never happened. No such meeting took place. No such conversation took place," Walker told the Judiciary Committee under oath. Dershowitz never produced any proof, and Walker was confirmed without dissent.

Dershowitz has launched similar public campaigns against other judicial nominees, against prosecutors, even against book reviewers who have criticized him. They are campaigns he appears to conduct with zeal, stoking them as they grow from small conflicts into brush fires of resentment and rumor, charge and countercharge.

Some lawyers, even many who admire Dershowitz's legal skills, question whether this proclivity for public combat does a disservice to his clients -- clients whose fates, after all, are in the hands of judges who have been the targets of Dershowitz broadsides, either individually or as a class. Leona Helmsley, for example, was tried by District Judge John Walker; Walker's new colleagues on the circuit court are the ones who will rule on her appeal.

Dershowitz himself says he is careful to warn clients of this baggage. "I'm only good if you want a certain kind of confrontational style in court," he says. "Of course I'm a liability to some clients; I'm the first one to tell them that."

Aside from administering that Miranda warning to prospective clients, however, Dershowitz makes no apologies for his combativeness. Indeed, it is the part of the Dershowitz legend of which he seems most proud. In "The Best Defense," he recalls that he was a tough kid who constantly got into fights. The worst fistfights, he writes, were with the Italian kids, "though I don't recall getting anything worse than a few deep cuts, several broken teeth and one concussion."

When Alan's mother, Claire, is asked about this, she throws an interesting new light on his self-portrait:

"He never really got into fights," she says fondly. "That's just a made-up story... . The only time his tooth was knocked out was when he played tennis and someone hit him with the tennis racket by mistake."

The Most Public Defender Offering a single note of levity in the panoply of hatred on Dershowitz's office door is a cartoon clipped from the New Yorker, showing a costumed man sitting at a desk over the caption "Look at it this way: If I weren't a very good lawyer, could I practice in a clown costume?"

It is hard to resist reading this as an admission of the occupant's drive for attention. Even his friends sometimes wonder at it. Says Boston lawyer Roanne Sragow: "I think Alan going on 'Nightline' is terrific. I think Alan going on the Brinkley show is great. He debated someone on 'Crossfire,' and he was fabulous. But I can't really see why he goes on 'Morton Downey.' "

Dershowitz explains that his mission is to spread the civil liberties message as widely as possible. "Which means I have to go on the Morton Downey show. I have to write for places like Penthouse."

It is the Downeys and Penthouses that make some of his Harvard colleagues wince. They disdain his neglect of legal scholarship -- viewed as the one true measure of a good law professor -- even as they may secretly yearn for a call from Ted Koppel.

"I don't know anyone who doesn't think Alan is smart," says a law school colleague, but "there are a very substantial number of people who say, what a waste, all that intelligence."

Inside the Outsider The same Harvard colleague muses, "There must be inner things that drive him that are more interesting than being the most famous law school professor in America."

Harvey Silverglate has some theories. "There are certain things in people like Dershowitz that are almost primordial, that he will never be able to get rid of," he says. "One of them is that he is surprised at his success... . He has an unparalleled career, and somehow has the feeling he's going to wake up one morning and find out it's all gone, it was a dream."

This, Silverglate theorizes, is one reason why he is so sensitive. For this is the flip side of the Dershowitz legend -- his volcanic response when anyone challenges it. Even relatively flattering articles about him draw scathing, multi-page, single-spaced counterattacks, and harsh ones draw veiled threats of libel suits, his civil libertarian credentials notwithstanding. He has more than once charged "journalistic malpractice."

Dershowitz will acknowledge that he is somewhat sensitive. But the phenomenon, Silverglate says, is beyond thin-skinned. "Thin-skinned is you don't like what they say about you. It's a little more than that: It's that he feels that he can't let these assaults go unanswered, because these people are trying to rip the world down around him."

Which leads Silverglate to the second thing about Dershowitz that he calls primordial -- an external insecurity, based on the belief that societal tolerance is a tenuous thing. "He lives," says Silverglate, "with the knowledge of the fragility of the veneer of civilization."

He tells the story of when Dershowitz lived in a Harvard-owned house near Brattle Street, among the best addresses in Cambridge, which the university offered to sell to him "at a very, very modest price." Dershowitz declined. Silverglate watched in chagrin for several years as the house's value rose some $40,000 a year, and still Dershowitz continued to rent. "And finally I sat him down one day and said, 'What is this? This is irrational.' And he realized what it was. Our relatives in Europe weren't allowed to own property. They had all of their worldly possessions in gold, in coins. ... And in fact, many of the European Jews who were saved, were saved because they had the goods with which to bribe border guards to let them out. So for years, Alan by instinct would not put his money into something that he couldn't put into his pocket and run."

Alan Dershowitz, outsider.

Eventually, a man who achieves money, status and widespread fame in America will cease to be an outsider. Late last year, Dershowitz finally bought a house. It is a nice one, just off Brattle Street. His neighbor, in a house across the street, is one William F. Weld, the state's blue-blooded Republican governor.

Alan Dershowitz, insider?

As a result of buying the house, Silverglate says of his closest friend, "He is in a period of great discomfort now."