This book traces how courtroom reckoning amid devastation forged enduring principles of accountability, transforming selective retribution into universal norms. It probes the tension between victors' adjudication and foundational legal innovation, where defeated power met allied judgment in a fragile new order. Three processes stand central: individual criminality that pierced sovereign immunity, establishing personal liability under international norms; crimes against humanity that codified peacetime atrocities as prosecutable offenses; and procedural precedent that balanced retribution with evidentiary rigor, influencing tribunals from Tokyo to The Hague. The Major War Criminals Trial at Nuremberg not only judged Axis leaders but embedded aggression as the supreme international crime, reshaping statecraft through law rather than conquest alone. Subsequent trials extended this framework across medical experiments, economic plunder, and host nation collaboration. German and European readers encounter here a mirror to postwar identity, where legal rupture from totalitarianism sustains democratic vigilance.