The discipline required by the military constitutes an hierarchical relationship. By this, it is meant that orders and commands from the top to ensure military operations are executed smoothly and successfully, and this is of crucial important especially during war time. Nevertheless, when executing an illegal superior order should the subordinate take for responsibility? The issue of accountability has been long discussed by international law scholars, and in practice many accused claim themselves to be following superior orders. Even though the main view holds that a defendant act pursuant to superior orders shall not constitute a defense per se after World War Ⅱ, there are still verdicts upheld otherwise. This article discusses the subject of 'defense of superior orders' with special emphasis on My Lai cases.