The control over standards of regulatory evidence is one of the factors that determine who may be called an expert, despite the level of scrutiny and contestation that surrounds claims to expertise, specifically in public and controversial environments. The history of the regulatory testing of genetically modified organisms shows that that standards of proof are simultaneously shaped in various inter-related spaces (industrial, academic, regulatory, civic spaces among others), and are thus varied, if not multiple. Standards of proof get selected or deselected, rise or fall, depending on what happens in this complex environment, or what may be called an ecology of regulatory knowledge, that heavily determines who may prove products safe or unsafe, and thus claim to be an expert.