It seems grimly appropriate that the last surviving prosecutor of the Nuremberg Trials — the moment Nazi evil met some form of comeuppance — is a Jew.

And yet the age of 100, Benjamin Ferencz does not display the rage of a man who witnessed the horror of the death camps — but instead reveals his satisfaction that he was able to help bring some of the Shoah’s perpetrators to justice.

Despite being Jewish, it was “not difficult” at all to hear the evidence given in the trial, he says, because he had “comprehensive documentary proof of the incredible slaughter of about one million Jewish men, women, and children — which I also witnessed as a member of the liberating forces at several concentration camps”.

The trials (there were 12 in all) opened on November 20 1945, and have become a byword for the application of fair and balanced judgment to war crimes, and also for new categories of crime — crimes against humanity, crimes of aggression and the crime of genocide.

In a new film by award-winning filmmaker Jenny Ash, the Nuremberg trials and their legacy are examined, showing spine-chilling original footage of the court proceedings in the first trial of 21 leading Nazis, including Herman Göring, Hans Frank and Julius Streicher.

And Ben Ferencz — who was a prosecutor in a later Nuremberg trial, that of the Einsatzgruppen officers — is on hand in the film to report some of the dreadful sights he saw while collating evidence.

Speaking to the JC from his home in Miami, Ben Ferencz makes it clear that the memories of the Nuremberg trials are still as sharp today as when he was visiting the abandoned concentration camps in the late spring and summer of 1945, after the war ended.

In the film, he says: “Until then, we didn’t even know the term ‘concentration camp’, we had no idea”. But, over horrific scenes of the slaughter in the camps, Mr Ferencz says: “The impact of my first visit was indescribable. There were bodies piled up like cordwood”.

Mr Ferencz told the JC: “Of course the trial could have been done differently. There were many possible ways of dealing with the criminals. The Russians, for example, would have shot them all without trial. It was the Americans who insisted upon giving them as fair a trial as was possible, and we succeeded in doing that.”

Ms Ash’s great coup in making the 90-minute documentary has been the securing of electrifying input from both Mr Ferencz and the globally acknowledged expert on the Nuremberg trials, Philippe Sands. Both men are steeped in knowledge about international law and how it is applied today — and that, they say, is due to Nuremberg and how the trials were conducted.

Mr Ferencz who, throughout his long career backed the establishment of the International Criminal Court, is in no doubt about the fairness of the Nuremberg proceedings. He told the JC: “Of course it’s possible to conduct a fairly fair trial even if the crimes are given a new name which more accurately describes mass murder”.

In an interview he gave to the Washington Post in 2005, Mr Ferencz talked about some of the rough and ready methods in use at the time. He recalled: “Someone who was not there could never really grasp how unreal the situation was ... I once saw DPs (displaced persons) beat an SS man and then strap him to the steel gurney of a crematorium. They slid him in the oven, turned on the heat and took him back out. Beat him again, and put him back in until he was burnt alive. I did nothing to stop it. I suppose I could have brandished my weapon or shot in the air, but I was not inclined to do so.”

Mr Sands, who has an intimate knowledge of Nuremberg, made clear that it nearly didn’t happen — because Winston Churchill “didn’t want a trial. He wanted them [the captured Nazis] lined up and shot”.

Churchill was talked round by US President Roosevelt, and by Stalin, who, Mr Sands says, “wanted a show trial.” Though the three men met at Yalta in February 1945 when the war was almost at an end, it was not until July 1945, in London, that a meeting took place to hammer out what became known as the Nuremberg Statute, the list of crimes under which the Nazis would be prosecuted.

That list was created with the input of two Jewish lawyers, says Mr Sands. One was Hersch Lauterpacht, a Galician-born immigrant to Britain who became a Cambridge professor and who devised Article Six of the Nuremberg Statute, which refers to crimes against humanity, war crimes and the crime of aggression. The other man was Raphael Lemkin, a Polish-Jewish lawyer who coined the word “genocide”, and who was adviser to the American chief prosecutor at Nuremberg, Robert Jackson.

In the documentary, we gradually see the effect on the defendants as they move from swaggering bravado to an appalled and sometimes tearful realisation that there was no escape from a damning verdict.

‘Nuremberg: The Nazi Trials’ will air on Channel 5 in the first week of December