<p>This research explores the institutional application of the “precautionary principle” to addressing scientific uncertainties, with a focus on how the international legal framework adjudicates environmental risks associated with the release of nuclear-polluted wastewater from the 2011 Fukushima Nuclear Disaster site. Scientific uncertainties tend to be amplified and escalated into political disputes due to the diversified assessments and standards on the potential risks of the discharged wastewater to public health in the East Asian region. This study asks: What institutional mechanisms can be an effective venue to manage scientific uncertainties and mitigate social amplifications of risk? This research analyzes the current legal frameworks, such as the United Nations Convention on the Law of the Sea (UNCLOS) and the World Trade Organization (WTO)’s resolution on genetically modified organism (GMO) imports to the European Union, to clarify the complexity of law and uncertainties and how they apply to the Fukushima case. Recognizing the innate gaps where technological assessment is limited, this paper suggests considering the precautionary principle as “gatekeeping” in international courts to bridge the gaps in conventional risk assessment. This approach aims to narrow methodological discrepancies between legal procedures and scientific corroboration on uncertainties, as a deliberative approach to scientific uncertainties in adjudication. Without such a mechanism, long-horizon environmental harms like those in the Fukushima case will continue to be excluded from international adjudication.</p>