Shimoda case (Tokyo District Court)

In this case, action for damages was brought against the State by Japanese nationals who were residents of Hiroshima or of Nagasaki when the nuclear weapons were dropped on these cities by the United States Air Force in August 1945. Most of the members of the plaintiffs' families were killed and many, including the plaintiffs themselves, were seriously wounded as a result of the bombings.The plaintiffs claimed damages, inter alia, on the ground that the dropping of atomic bombs as an act of hostilities was illegal under the rules of positive international law then in force (taking into consideration both treaty law and customary law).Shimoda case (Compensation claim against Japan brought by the residents of Hiroshima & Nagasaki), Tokyo District Court, 7 December 1963. Source: Hanrei Jiho, vol. 355, p. 17; translated in The Japanese Annual of International Law, Vol. 8 (1964), p. 231, accessed via the website of the ICRC.

The Court denied that the plaintiffs had a right to compensation, but held that the aerial bombardment with nuclear weapons of the cities of Hiroshima and Nagasaki was an illegal act of hostilities according to the rules of international law, and that it must be regarded as indiscriminate aerial bombardment of undefended cities, even if it was directed at military objectives only, inasmuch as it resulted in damage comparable to that caused by indiscriminate bombardment.

The Court noted that the atomic bomb was a new weapon, and that it was, hence, not expressly prohibited in positive international law, neither by a customary rule nor by treaty law. But the Court argued that the use of a new weapon can be deemed to be contrary to the principles of international law which are at the basis of positive rules of international law, and found that any weapon the use of which is contrary to the customs of civilized countries and to the principles of international law should ipso facto be deemed to be prohibited even if there is no express provision in the law.

The case is consequently of broader interest with respect to the obligation on states parties to 1977 Additional Protocol I to the Geneva Conventions, under Article 36 of that treaty, to determine 'In the study, development, acquisition or adoption of a new weapon, means or method of warfare, ... whether its employment would, in some or all circumstances, be prohibited by this Protocol or by any other rule of international law applicable to the High Contracting Party'.

Last updated on: 01 December 2013