Counterfactual thinking is used to analyse historical events or the effectiveness of political regimes. It is also used to show the contingency of events. What if we were to apply counterfactual thinking to the international regulation of fisheries? Would it help improve our understanding of fisheries law? This paper breaks new ground by using counterfactual analysis to free up thinking about how we can regulate fisheries free of the bias of necessity (if the past) free analysis from the bias of necessity; to explain the workings of law without recourse to abstract theories; and to stimulate imaginative thinking. If law is not inevitable, but in part the result of historical contingencies, then by foregrounding these contingencies we can strengthen calls for change to address any shortcomings that are the product of those past, less relevant, contingencies. The paper shows that the systemic complexity of international fisheries and environmental law make it difficult to posit clear and instructive counterfactuals. As such we have to be very cautious about the lessons that we draw.However, one encouraging lesson is that it is precisely the systemic complexity that inhibits counterfactual thinking that might actually serve us well in developing a stronger environmental dimensions to fisheries management in the longer term.