On 9 March, research team Institutions for Collective Action had a double open seminar. Grant Halliday, historian and research intern at RSM Erasmus University, gave an insight into the development of rules and sanctions in medieval and early-modern fishery cooperatives in Spain. Dr. Florian Grisel, associate professor at the Oxford Centre for Socio-Legal Studies, complemented Halliday’s findings with a presentation about another fishery cooperative, the Prud’homie de Pêche of Marseille. In the subsequent discussion, the attendants considered the existence of norms versus formal legal structures, as well as the continuation of such organizations over centuries.