Historians have to be 'very brave and indefatigable' in pushing for the truth, says Deborah Lipstadt, a history professor in the US and author of the book Denying the Holocaust - the Growing Assault on Truth and Memory. Professor Lipstadt, 60, prevailed in a six-year legal battle with British Holocaust denier David Irving who sued her for libel over that book. The Atlanta-based academic, invited to Hong Kong for a Jewish community centre programme, believes that facing up to history liberates nations and people from living a lie. 'Why do psychologists try to force people to find the truth in their past? Because it doesn't go away,' she said during her visit last week. 'Everybody uses history selectively. The more totalitarian the regime the more likely they are to control that kind of history.' Professor Lipstadt and her defence team, which included Princess Diana's solicitor Anthony Julius, made their own history in the libel trial eight years ago in London. She is still at the front line whenever Holocaust denial arises, tracking and exposing it through her blog. In her 1993 book Professor Lipstadt described author David Irving as 'a Hitler partisan wearing blinkers'. She said he distorted evidence, manipulated documents and misrepresented data 'to reach historically untenable conclusions'. After Penguin UK published the book in Britain, where a defendant in a libel action must prove the truth of what he or she wrote, Irving sued. The defence strategy was not to prove that the Holocaust happened - 'any more than it is necessary to prove that the second world war happened', said Professor Lipstadt. This obviated the need to call Holocaust survivors as witnesses, sparing them the likelihood of distressing cross-examination by Irving, she added, who represented himself in court. Instead, the defence team set out to furnish scholarly proof, with other historians as expert witnesses, that her statements about Irving were true. The trial preparation involved intricate analysis of his writing, footnotes and use of sources, and 'a forensic journey' to the Auschwitz concentration and extermination camp. At the end of the 12-week trial, the High Court judge delivered a 355-page judgment saying it was 'incontrovertible that Irving qualifies as a Holocaust denier'. The judge found that he was an anti-Semite and a racist, had deliberately falsified the historical record and 'was motivated by a desire to present events in a manner consistent with his own ideological beliefs even if that involved distortion and manipulation of historical evidence'. The trial took over and 'shaped my life', said Professor Lipstadt, who recounted the experience in her 2005 book History on Trial - My Day in Court with a Holocaust Denier. She has turned down attempts to embroil her in debate with Irving. 'I can't debate a Holocaust denier because on the Holocaust there are not two sides of the issue. I'm not saying you can't debate things about the Holocaust - there are all sorts of things historians differ on - but not whether it happened, because that's a fact,' said Professor Lipstadt. 'And when you know that the arguments the deniers are making are based on lies and mis-statements of truth, then you certainly can't debate.' Holocaust deniers often used the issue of free speech as a smokescreen, she said. They claimed they were being 'shut down' by doctrinaire historians, and portrayed themselves as 'the ones who are really balanced and open minded'. An invitation to Irving last November to address the Oxford Union debating society on free speech ignited a furore in Britain over how far the principle that everyone is entitled to their say should be tested. In a statement supporting hundreds who protested outside the venue Professor Lipstadt said: 'Some of those who have defended the Oxford Union have called for open minds. The problem with people with open minds is that sometimes their minds are so open their brains fall out.' She saw the issue of free speech as a matter of what constraints governments imposed. 'It's not a matter of my obligation to provide the person who is saying these words - especially if they're hateful, prejudicial words - with a platform to say them.' She said that far from being a champion of free speech, Irving had sued her to silence her. Yet Professor Lipstadt said she derived no satisfaction when in 2006 Irving was imprisoned in Austria after pleading guilty to Holocaust denial, which is a crime there. She opposed censorship and did not believe that laws against Holocaust denial were wise as they made martyrs of the accused. 'The way of fighting Holocaust deniers is with history and with truth,' she said. She said there had been many instances of denial in history, from past refusal to acknowledge the mistreatment of North American Indians and Australian Aboriginals, to denial of the massacre of Armenians in Turkey during the first world war and the Nanking Massacre in 1937-38. She found it hard to believe that a generation had grown up in China knowing little about the Tiananmen Square crackdown in 1989. 'The thing that you're trying to hide, that you're ashamed of, sits like an 800-pound gorilla in the middle of the table and you make-believe it's not there,' said Professor Lipstadt. 'Then you try to create ways of getting round it, over it, under it, and it's there in your life, you're just not admitting it. It's detrimental to a country's well-being to ignore or to deny what happened.' Professor Lipstadt, who is the Dorot Professor of Modern Jewish and Holocaust Studies at Emory University, described history as 'very controversial' and the past as her context for seeing the present. 'Don't just show me what's happening now, give me a context, give me a background,' she said. 'That is history's great gift.'