'I was particularly swayed by Hannah Arendt's phrase "the banality of evil" to describe how ordinary people got caught up in the Nazi regime, because the defendants in the Frankfurt trials were not important figures,' he says. 'They were mostly ordinary men following orders, Yet, in executing those orders, they used their own personal cruelty and that's significant. Some people mixed up the ideas of war and genocide, as if the acts that took place were acts of war. This is an argument we also find in Rwanda. Some who have admitted to crimes justify them by saying they considered they were at war and under attack. It is a way of denying the genocide by claiming it was war.'