In lawsuits involving scientific controversies, scientists and judges assert epistemic authority by demarcating their respective domains and roles. Science and Technology Studies and Socio-Legal Studies have shown that what is scientific and what is legal is not always clearly defined in litigation given science and law’s intertwined relations and mutually constitutive interactions. There is however limited scrutiny of how scientists’ and judges’ constructions of their own and each other’s roles shape the performance of their functions and the course of adjudication. The project aims to examine the co-construction of scientific and judicial roles by analysing, as a case study, the Philippine court battle questioning field experiments of genetically modified (GM) eggplant. This 2016 case was the first and so far the only GM issue decided by the Philippine Supreme Court. The project will surface congruences and incongruences in role constructions, and how scientists and judges navigate differences in their expected and actual tasks in legal proceedings. Through the case, the project seeks to contribute to both theoretical and practical understandings of the techno-legal interface and the productive engagement between science and law, particularly in biotechnology governance.