In 2001, I wrote an Expert Report to support the defense of Deborah Lipstadt and Penguin Books against the libel accusations of David Irving.
David Irving had sued Deborah Lipstadt in the UK for libel because of the fact that she identified him as a Holocaust denier, Hitler apologist, distorter of history, antisemite and racist in her book Denying the Holocaust. It should be noted that Lipstadt did not choose the legal system as the place to fight this battle. By suing her for libel, Irving threatened her right of free speech as well as the accuracy of the historical record. As a US citizen, Lipstadt could have conveniently ignored the suit and relied on the protections of the US First Amendment. Instead, she courageously rose to the challenge, deciding that UK legal precedent is of historical importance. She defended herself using the defense of justification. Her book was not libel because it was true. She won the suit, Mr. Justice Gray found that the defense of justification was in fact a valid one.
Irving appealed the decision and Lipstadt won again.
Much of the work of that report was a refinement of an article I wrote with Jamie McCarthy called Chemistry is not the Science: Rudolf, Rhetoric, and Reduction
See also the postscript to that article.
I also wrote an earlier article called The Chemistry of Auschwitz
The Holocaust History Project is an excellent resource on Holocaust denial.