David Irving picked on the wrong Jew. Before he sued the historian Deborah Lipstadt in the fall of 1996, Irving was widely regarded as an indefatigable researcher, a specialist on the history of the Second World War whose work, according to Stanford professor Gordon Craig, played “an indispensible part in the historical enterprise.” Sir John Keegan, the British military historian, wrote that Irving’s books were essential reading “to anyone seeking to understand the war in the round.”

There were always a few dissenters. As far back as 1981, Kai Bird noted the rank seam of anti-Semitism running through Uprising!, Irving’s account of the 1956 Hungarian revolt. The Scottish journalist Neal Ascherson called Irving “Jew-obsessed.” But Bird, now a distinguished historian, was a Nation editor at the time, while Irving was a fixture of the British press whose professed view that Auschwitz was merely, in Craig’s paraphrase, “a labor camp with an unfortunately high death rate” was treated as little more than an intellectual eccentricity.

As for Lipstadt, neither the solid scholarship of her first book, Beyond Belief: The American Press and the Coming of the Holocaust, nor the dutiful debunking in Denying the Holocaust seemed likely to raise her profile beyond the well-upholstered ghetto of Jewish book festivals and speeches at synagogue luncheons. Yet while Irving’s views had little impact on his reputation, Lipstadt’s depiction of him as “one of the most dangerous spokespersons for Holocaust denial” was beginning to cut into his American sales. Her second book also provided the ammunition for a campaign—ultimately successful—to persuade St. Martin’s Press, his American publisher, to cancel the contract for his biography of Nazi propagandist Josef Goebbels.

Under American law, with its emphasis on protecting free speech, plaintiffs who sue for libel have to prove that what has been said or written about them is false. Anyone with Irving’s notoriety would also have to prove they’d been libeled “in reckless disregard” of the facts. British libel law is very different, valuing the defense of reputation more than unhindered comment, so the burden of proof is on the defendant. By suing Lipstadt in Britain, Irving forced her to actually prove that her description of him as “a Hitler partisan” who distorts evidence and twists historical data was accurate. It was precisely this stacked deck of British law, which had led so many previous defendants against Irving to settle—in the process providing the writer, who acted as his own lawyer, a nice second income. Indeed, Lipstadt herself was widely advised to settle—both by well-meaning American friends who couldn’t see the point of schlepping to London for a lengthy and expensive trial to prove something every sane person already knew. And by some British Jews who, aware of the law’s inherent bias and the capriciousness of juries, feared that the consequences of failure would go far beyond financial damage.

Because Irving’s defense against the charge of being a Holocaust denier was that the Holocaust—the systematic attempt by the Nazis to exterminate the Jews of Europe—had never happened (or, as he frequently joked, “more women died on the back seat of Edward Kennedy’s car at Chappaquiddick than in the gas chambers at Auschwitz”), Lipstadt would have to defend more than her own historical integrity. She’d have to defend our historical knowledge of the Holocaust itself.

This case is not about history, it is about David Irving’s credibility, Lipstadt told me when I interviewed her for The New York Times on the eve of the 1999 trial. Anthony Julius, the brilliant British lawyer who put together Lipstadt’s defense, was equally uncomfortable with any suggestion that the trial had any historical significance. Dealing with Irving, he told me, “is like dealing with shit on your shoe. You have to clean it off. But you don’t need to think about it too much.” Yet Julius devoted years of his life to the case. And when it came time to publish her memoir, Lipstadt titled it History on Trial—perhaps because I’d already taken The Holocaust on Trial for my own account of the proceedings.

The new film Denial has brought Lipstadt’s book to the screen. Director Mick Jackson effectively captures the claustrophobic atmosphere of the trial. And if some of the casting stretches the truth a bit—Rachel Weisz, who delivers a compelling portrayal of Lipstadt’s immense frustration at not being allowed to testify in her own defense (to keep the focus on Irving’s distortions), resembles the real Lipstadt about as much as I do Brad Pitt—Andrew Scott gets Anthony Julius’s intellectual aggression down perfectly. And Tom Wilkinson’s performance as Richard Rampton, the Scottish barrister brought in as a hired gun who becomes deeply invested in the case, is the film’s emotional core.

When we first meet Rampton, he’s an irascible eccentric, who on a field trip to Auschwitz insists on pacing out the distances for himself, while constantly badgering Lipstadt and Robert Jan van Pelt, the defense’s expert witness (“How do we know? What’s the proof?”). Since the Nazis went to great pains to keep the extent of their crimes secret, the answers are not always satisfying.

Conveying that truth—and then placing the answers in a context that allows us not just to understand the history, but to appreciate how we know what we know, is the first great achievement of David Hare’s mostly spare screenplay. Rather than dismissing his protagonists’ anxiety, Hare lets us feel—as I felt, sitting in the press box every day—that the outcome was far from a forgone conclusion.

Hare’s second great coup was to turn what in fact was a series of disjointed, thoroughly dispiriting testimonies about the worst episode in human history into a kind of platonic love story. By putting the growing trust and mutual regard between Rampton and Lipstadt at the center of his film, rather than the confrontation between Lipstadt and Irving, Hare gives it—and the audience—a happy ending.

The reality was messier—and a lot of that mess had to do with Irving, played, by Timothy Spall, as the much-diminished figure he became after the trial, not the swaggering pedant who ran rings around Hugh Trevor-Roper and other academic historians. Richard Evans, the belligerent Welsh historian who dismantled Irving’s reputation, exposing distortions and fraud throughout his entire body of work—not just about the Holocaust, but on subjects, such as the firebombing of Dresden, that had little to do with Jews—barely figures in Denial. Nor are we given much of a sense of Justice Charles Gray—who before the trial told me, “Judges aren’t historians,” and ended it by writing, “No objective, fair-minded historian would have serious cause to doubt that there were gas chambers at Auschwitz.”

Lipstadt won her case—as she should have. Thanks to her and her defense team the facts of the Holocaust are perhaps less subject to dispute. But the meaning of those facts—and the political uses to which they are put—remains contested. Like Lipstadt’s memoir, Denial shows little interest in that dispute. If it had it might have made for better history—though perhaps a less watchable movie.