Taking the debate on the contribution of laypeople to law-making and judicial interpretation as a starting point, the chapter analyses the role that laypeople play in producing law. For that purpose, the current debate on whether ecocide should be introduced as a crime in international environmental law serves as an illustrative case. Drawing on my empirical analysis, I argue that the paradigm shift in environmental law from the regulation of natural resources to environmental liability and penal provisions for ecocide can be explained by the agency of laypeople in environmental law. Most importantly, laypeople contribute to the input, throughput, and output legitimacy of new legal provisions. At the same time, the increasing prevalence of laypeople in environmental law brings about new challenges in environmental governance and differs across countries.