Who is responsible when an AI weapon pulls the trigger?

In 1863, Francis Lieber, the Prussian-American jurist commissioned by Abraham Lincoln to codify the laws of land warfare, wrote that no soldier may kill an enemy "who has laid down his arms." War, however brutal, must remain an act performed by a morally responsible agent who can account for what he has done and to whom it has been done. The Lieber Code was imperfect. Its application was racially selective and its humanitarian ambitions frequently betrayed in practice. But its foundational premi...