History's Day in Court

I am currently reading D.D. Guttenplan's The Holocaust on Trial, which is about the law suit brought against Deborah Lipstadt by the infamous Holocaust denier David Irving. Lipstadt, in her book Denying the Holocaust, accused Irving of being a dangerous Holocaust denier. Irving brought suit against Lipstadt for libel in the British court system. In the British legal system the burden of proof is on the defendant, which the opposite of the American legal system. By bringing suit in Great Britain, Irving was hoping to put the Holocaust itself on trial. Lipstadt would have to prove that the Holocaust did, in fact, happen.

So far this book is leaving me with many tough questions. How do we 'take on' Holocaust deniers? How can trained historians 'prove' that the Holocaust did happen?
This is an interesting and important issue, which has ramifications beyond Holocaust denial. It is a threat to history and collective memory. If trained historians do not take on people like the Irving in public square and expose the fallacies and sheer lunacy of their ideas, then we are giving them carte blanche over the past. The public, whose historical knowledge is fairly limited, may be persuaded by these ideologues, which could result in a society that is oppressive and uneducated.

I will post more on this topic as I finish reading the book.