The 1919 Report of the Commission on the Responsibilities of the Authors of War and on Enforcement of Penalties is the genesis of crimes against humanity (CAH) in international law. The report was presented to the Preliminary Peace Conference that brought about the Treaty of Versailles and concluded World War I.

The Commission was established by the victorious Allies for purposes of bringing to trial persons of the defeated powers that the Allies believed to have committed war crimes under customary international law as embodied in the Convention Respecting the Laws and Customs of War on Land and Annexed Regulations.

The Preamble of the 1907 Hague Convention states that its contents reflect the customary practices of states that were deemed to exist at the time that the convention was adopted. The Preamble implicitly states that the contents of the Annexed Regulations do not reflect all that is part of the “laws of humanity” that inspired the contents of the Regulation, but only that portion of it that the State Parties had agreed upon at the time. The Preamble recognizes that a concept exists, referred to as “the laws of humanity,” that embodies the human and humanitarian values that are at the basis of the international regulation of armed conflicts.