On April 24, 1945, my mother, Dr. Hadassah Bimko Rosensaft, gave one of the first eyewitness accounts of the horrors of the Holocaust on a Movietone News newsreel that was filmed at the recently liberated Nazi concentration camp of Bergen-Belsen. When British troops had entered Bergen-Belsen near the German city of Hanover nine days earlier, they encountered a devastation of human misery for which they were utterly unprepared. More than 10,000 bodies lay scattered about the camp, and the 58,000 surviving inmates, the overwhelming majority of them Jews, were suffering from a combination of typhus, tuberculosis, dysentery, extreme malnutrition and numerous other virulent diseases. My mother, a not yet 33-year-old Jewish dentist from Poland, was among the survivors. Her parents, first husband, five-and-a-half-year-old son and sister had all been gassed at Auschwitz-Birkenau, where she had spent more than 15 months before being sent to Bergen-Belsen in November 1944. With the war still ongoing, Brigadier H. L. Glyn-Hughes, the deputy director of medical services of the British Army of the Rhine, appointed her to organize and head a group of doctors and nurses among the survivors to help a skeleton military medical team care for the camp's thousands of critically ill inmates. One week after the liberation, British Movietone News arrived at Bergen-Belsen to record the evidence of Nazi Germany's crimes. In the newsreel, my mother spoke forcefully and defiantly in fluent German, choosing her words carefully, without faltering. Dressed in a white medical coat, she looked straight into the camera. "It is difficult for me to describe," she said, "all that we inmates experienced here in the camps. As a small, very small example I can relate that we inmates were thrown onto the earth of a filthy, lice-filled camp, without blankets, without bags of hay, without beds. We were given a 12th of a piece of bread daily and one liter of turnip soup so that almost 75 percent of the inmates were swollen from hunger. A severe typhus epidemic broke out, and the hunger and the typhus devoured us." Through the camera she told the world how the Germans had refused to give starving inmates food shipments sent by the Red Cross until shortly before the arrival of British troops, and how the camp's SS commandant had stolen large quantities of chocolate intended for Jewish children to enrich himself on the black market. Five months later, my mother was one of the principal witnesses for the prosecution at the first trial of Nazi war criminals. In her testimony before a British military tribunal at Lueneburg, Germany, she described in detail the brutality and sadism of the SS officers and guards at Auschwitz and Bergen-Belsen. ON HER SECOND day on the witness stand, one of the court-appointed defense attorneys suggested, according to a report published in The New York Times of September 23, 1945, that my mother's statement that she had seen one of the defendants kick and beat the inmates was "pure fabrication." "I would like to point out," my mother replied, "I was present and not the defending counsel during those conditions that I have described." This incident might be dismissed as one lawyer's overzealous trial tactic, were it not for another news item published on the same page as the report of my mother's testimony. There, Gen. George Patton, head of the US military government of Bavaria, is quoted as saying that "this Nazi thing is just like a Democratic and Republican election fight." Fast-forward to Patrick Buchanan, senior White House official under presidents Nixon and Reagan and one-time arch-conservative candidate for the Republican presidential nomination, who wrote in his March 17, 1990, syndicated column that it would have been impossible for Jews to perish in the gas chambers of the Treblinka death camp. In the same column, Buchanan referred to a "so-called Holocaust survivor syndrome" which he described as involving "group fantasies of martyrdom and heroics." And then fast-forward still further to Bishop Richard Williamson, the renegade Roman Catholic cleric whom Pope Benedict XVI sought to rehabilitate earlier this year, who declared on Swedish television that "I believe that the historical evidence is largely against, is hugely against six million Jews having been deliberately gassed in gas chambers as a deliberate policy of Adolf Hitler... I believe there were no gas chambers." Bishop Williamson is not alone. In December 2006, Iranian President Mahmoud Ahmadinejad convened an international pseudo-academic conference in Teheran entitled "International Conference on 'Review of the Holocaust: Global Vision," in which such luminaries as David Duke, the erstwhile Imperial wizard of the Ku Klux Klan, "debated," in effect, whether or not my grandparents and my brother had in fact been gassed at Auschwitz. Six months after my mother died in October 1997, I was at Auschwitz-Birkenau with our daughter Jodi, then a college sophomore. We walked in silence past the decaying wooden barracks. After 15 or 20 minutes, Jodi turned to me and said, "You know, it looks exactly the way Dassah [which is what she called my mother] described it." I realized that a transfer of memory had taken place. My daughter, born 33 years after the Holocaust, had recognized Birkenau through my mother's eyes, through my mother's memories. For the past 64 years, the survivors have fought against those who seek to deny or trivialize the genocide of European Jewry. Now, as the Holocaust's witnesses fade into history, we as a society must make their cause our own by absorbing their memories into our collective consciousness. The survivors' personal testimonies, including my mother's words on the Movietone newsreel and her posthumously published memoirs, are their lasting legacy. They are also our most powerful antidote against contemporary and future Holocaust deniers. The writer is general counsel of the World Jewish Congress and adjunct professor of law at Cornell Law School. He is the founding chairman of the International Network of Children of Jewish Holocaust Survivors.