Field experiments related to the development of geoengineering technologies are now occurring in an increasing number of countries. Such projects are raising important questions about the adequacy of national environmental protection laws (EPLs) for regulating geoengineering activities, including their ability to enforce emerging international norms for geoengineering research. This article considers the application of the Canadian Environmental Protection Act (CEPA) to a recent controversy over ocean iron fertilization off the coast of British Columbia. This incident provides an important precedent for analyzing existing domestic legislation and administrative measures being called upon to regulate geoengineering activities outside of the laboratory. To date, the attention of legal scholars has mostly focused on the content and adequacy of international rules. However, as this case illustrates, the interpretation and implementation of these rules in domestic legal systems is critically important, as it is predominantly within domestic frameworks that such rules have direct legal effect on private and nongovernmental actors. Our analysis highlights some key challenges for EPLs in regulating geoengineering activities, and draws some tentative conclusions regarding the structure of domestic environmental protection frameworks for regulating geoengineering research