Abstract: On 21 December 2016, the United Nations General Assembly took a historic step in establishing a Mechanism to investigate and preserve evidence of international crimes in Syria, the first time the Assembly has established such a body. This essay assesses the General Assembly’s legal authority to create such an organ, and situates the move in the larger story of the international criminal justice project. The establishment of the Mechanism at the same time highlights the political fragility of the justice project — the Mechanism’s creation was necessitated by the political stalemate blocking accountability for crimes in Syria — and underscores the creativity and ingenuity in the development of institutions, cases and the law that have marked the international criminal law movement over the last decades.