Analysis of state responsibility for Japan’s nuclear-contaminated water discharge into the sea

Abstract The oceans and seas are the common heritage of humanity and should, therefore, be protected. Japan, as a state party to the United Nations Convention on the Law of the Sea, discharged noncompliant nuclear-contaminated water into the Pacific Ocean without fulfilling its obligations of notification and consultation, which is a violation of several international commitments and international principles. Japan’s act of discharging nuclear-contaminated water into the sea meets the constitutive criteria of state responsibility of the Draft Articles on Responsibility of States for Internationally Wrongful Acts, which has no exemptions, so Japan should bear state responsibility. Given the obstacles to the identification of damage, the lag in the mechanism of ex post facto liability and the difficulties in the implementation of state liability in practice, corresponding solutions are proposed: At the international level, clear criteria for determining damage should be established, and a system for disposing of nuclear wastewater should be set up based on the principle of risk prevention; at the domestic level, consideration should be given to the adoption of interim measures and the initiation of domestic litigation based on investigation, evidence collection, and information exchange.