The recent proposal by an International Expert Panel to include the crime of ecocide in the International Criminal Court’s Rome Statute has raised expectations for preventing and remedying severe environmental harm through international prosecution in the Anthropocene. As alluring as this image is, however, we argue that ecocide prosecutions may be the most difficult, perhaps even impossible, in precisely the cases that the ICC would be most concerned with, namely, the gravest global incidents of environmental damage, especially those associated with planetary climate change. Here, we explore a series of questions about the Panel’s formulation of ecocide that resonate with longer debates around criminalizing environmental harm but take on new dimensions amidst global climatic disruption and after twenty years of ICC trials. Ecocide must thus contend with the hard lessons learned concerning the ICC’s limitations in realizing justice in a fraught international political context and also fundamental challenges to knowledge arising from the dynamic ecology and uncertainty of the Anthropocene. The proposed amendment, if adopted, risks ineffective prosecutions or perverse outcomes for justice and even the environment itself. This risk, however, may characterize not just the Panel’s proposal but perhaps any effort to prosecute ecocide internationally in the Anthropocene.