In 1921, the Armenian student Soghomon Tehlirian assassinated the former Grand Vizier of the Ottoman Empire and chief perpetrator of the Armenian genocide, Mehmed Talât. After a cursory two-day trial Tehlirian was surprisingly acquitted by a Berlin court. The trial turned into a tribunal on the victim's crimes against humanity, and it made legal history. Even Raphael Lemkin, the "founding father" of the UN Genocide Convention, has always referred in his lifetime to this spectacular Berlin trial of June 2-3, 1921 as his initial experience to coin the term genocide. Hannah Arendt cited the trial strategy as a reference in her book Eichmann in Jerusalem. The lecture sheds light on the background of the trial and its impact on the development of international law.