ALT ABSTRACT This paper examines evolving definitions of ecocide since the 1970s and the legal and political challenges facing its recognition as an international crime. Drawing on historical and contemporary formulations, we propose a definition that balances foreseeability with flexibility, includes reckless acts and omissions, and resists narrow cost-benefit constraints. While cautiously supportive of ecocide’s criminalisation, we emphasise the significant political and operational barriers to establishing it as a fifth core international crime. We argue for attention to domestic criminalisation efforts and the role of non-binding international measures in enhancing accountability for environmental harm. Ultimately, we advocate for ‘legal humility’: recognising the limits of criminal law and understanding ecocide not as a singular solution but as one of many tools needed to confront environmental destruction. Criminalisation should complement, rather than replace, broader legal and poli