A growing body of research has documented the important role of deliberate norm change in prompting institutional reform, including via international courts and advocacy networks. This paper examines advocacy to criminalise ecocide at the international level via an amendment to the Rome Statute of the International Criminal Court. It analyses how advocates are developing and diffusing the content of an emerging norm against ecocide. The analysis shows how their actions depend on three key processes: foregrounding (putting a spotlight on harmful existing norms), innovation (developing a new normative framework), and grafting (linking the innovation to more established norms), and highlights how these processes are embedded in a broader tactic of information politics to persuade publics of the need of a legal solution to effectively address ecocide as an intractable problem. Examining these processes can help solidify our understanding of how norms play a role in efforts to bring about significant change on issues related to environmental conservation and sustainability.