The first of a series, this research paper by the Human Rights Consortium at the University of London details the history of the Law of Ecocide from the 1970s, revealing that it was ultimately dropped from the ILC discussions in 1996. The authors trace the term “ecocide,” used as early as 1970 when Professor Arthur W. Galston proposed “a new international agreement to ban ecocide.” While “ecocide” was not included in the official outcome document, the term was popularized at the 1972 Stockholm Conference, where, “perhaps for the first time,” environmental issues enjoyed international attention. The authors then discuss various academic attempts to define “ecocide,” followed by Raphael Lemkin’s “cultural genocide,” which, were it included in the 1948 Convention on Genocide, could have criminalized ecocide as a method of genocide. The authors also analyze discussions at the ILC on the subject of a Law of Ecocide, including intent requirements and political arguments leading to the ultimate exclusion of Article 26 from the Draft Code of Crimes Against the Peace and Security of Mankind, which ultimately evolved into the Rome Statute. Noting that some states have criminalized ecocide in their national penal codes, the authors conclude by arguing for codifying ecocide as the fifth international crime against peace.