There’s actually a film coming out about the Nuremberg Trial and about how the army psychologists did regular checks on the defendants to assess their suitability to stand trial. Now Rudolf Hess who flew over to Britain in 1941 and was kept as a prisoner of war until moved back to Germany for the trial, actually feigned amnesia….claimed that he didn’t even remember his wife when she came to visit him (although quickly and conveniently regained his memory)
But what came out was that there was something ingrained in Germans culturally to be obedient and not question authority or orders. But it was more than that, it wasn't that obedience overrode the ethical considerations…the ethical considerations just weren’t there. Rudolf Hoess who was the commandant of Auschwitz, wasn’t a defendant at Nuremberg but he was brought in as a character witness, and under cross examination was completely matter of fact about what he did.
Not in a ranting scene chewing act of villainy, but just very coldly stated the methodical process of exterminating Jews in the most efficient way.
There were those at the trial who tried to deny the extent of their own involvement (like Goering) and some who were still so supportive of Nazi ideology that they proudly boasted about what they did. But there were some like Hoess, who actually couldn’t conceive of having done anything wrong (well that was until just before his execution where he readopted his Catholic faith, and renounced Nazism)