Cesarani campaigned against Holocaust deniers such as David Irving and Fredrick Töben, alongside fellow academic Peter Longerich. With regards to Holocaust denial, he wrote that "the fractional loss of liberty entailed in penalising the expression of neo-Nazi views or Holocaust denial seems a small price to pay compared to what can follow if the far right is shielded all the way into power". Journalist David Guttenplan described Cesarani's position in the wake of the "Irving v Lipstadt" trial as "more dangerous than anything David Irving has ever said or written."