Rethinking non-retroactivity: mala in se crimes and the ethics of genocide prosecution

Abstract

This paper examines whether the expansion of post-colonial states into Indigenous territories – specifically the Conquest of the Desert in Argentina (1878–1885) – constitutes genocide under the Convention on the Prevention and Punishment of the Crime of Genocide (CPPCG). A central challenge in this analysis is the principle of non-retroactivity, which prohibits punishing conduct that was not legally defined as a crime at the time it was committed. I argue that while retroactive punishment is forbidden, retroactive recognition of genocide is not. Drawing on legal and philosophical arguments, the paper contends that the Conquest of the Desert satisfies the criteria for genocide established by the CPPCG. At the same time, recognising these events as genocide does not violate the principle of legality, because the underlying acts were already punishable under the criminal law in force at the time. Courts may therefore characterise such conduct as genocide while applying the penalties prescribed by the law applicable when the crimes were committed. This approach allows the legal system to acknowledge the specific gravity of genocidal violence while respecting the prohibition of retroactive punishment, contributing to ongoing debates on historical justice and accountability for past human rights violations.