Which principle was established by the nuremberg trials after world war ii?

Individuals can be held responsible for their role in state-sponsored war crimes and atrocities.

German officials placed on trial for war crimes offered the defense that they were only following orders from superiors, and thus they personally were not the ones to be held responsible.  "An order is an order," was the way those serving under Hitler's regime sought to defend themselves from punishment.  The Nuremberg Trials did not accept this defense because the nature of the actions was so obviously wrong that those sorts of orders should not be obeyed.  Those who perpetrated the Holocaust were to be held responsible for it.