Today, deep concern prevails among the international community over the catastrophic human consequences of any use of nuclear weapons. On the basis of this shared concern, 125 states issued a joint statement in the United Nations General Assembly First Committee on October 21, 2013, stating the following: “It is in the interest of the very survival of humanity that nuclear weapons are never used again, under any circumstances”; “all efforts must be exerted to eliminate the threat of these weapons of mass destruction”; and “the only way to guarantee that nuclear weapons will never be used again is through their total elimination.” This declaration for the total elimination of nuclear weapons with recognition of the humanitarian impacts, strongly suggests the illegality of the use of nuclear weapons under the context of the existing international law. 
International (humanitarian) law already exists among humankind, which illegalizes any use of weapons leading to a non-humanitarian outcome. 50 years ago, on December 7, 1963, the Tokyo District Court handed down a decision on the Shimoda Case (Ryuichi Shimoda et al. v. The State), or so-called, “the Atomic Bomb Trial.” The decision stated, that “since an aerial bombardment with an atomic bomb [by the United States Air Force] brings the same result as a blind aerial bombardment from the tremendous power of destruction, even if the aerial bombardment has only a military objective as the target of its attack, it is proper to understand that an aerial bombardment with the atomic bomb on both cities of Hiroshima and Nagasaki was an illegal act of hostilities, as the indiscriminate bombardment of undefended cities.” It also concluded that “it is not too much to say that the pain brought by the atomic bomb is severer than that from poisons and poisonous gases, and we can say that the act of dropping such a cruel bomb is contrary to the fundamental principle of international laws of war that unnecessary pain must not be given.”
Furthermore, the framework for this ruling is the same as that for the International Court of Justice’s Advisory Opinion on “Legality of the Threat or Use of Nuclear Weapons (1996), which states, “the threat or use of nuclear weapons would generally be contrary to the rules of international law applicable in armed conflict, and in particular the principles and rules of humanitarian law.” Taking this into account, the Council of Delegates of the International Red Cross and Red Crescent Movement stated in its 2011 Resolution, “to find it difficult to envisage how any use of nuclear weapons could be compatible with the rules of international humanitarian law.”

Nevertheless, nuclear-weapon states and client states are conducting affairs as if laws prohibiting nuclear weapons do not exist, relying on nuclear deterrence for maintaining their national security. In their view, outlawing of nuclear weapons is the goal to be achieved in the distance future. In the meantime, nuclear weapons remain to be great threat to humankind. Taking such position is in fact “being responsible to itself alone,” and “ignoring” the interest of the very survival of humanity.
Security issues are becoming far more significant in today’s world. Security can only be genuinely attained under “international peace based on justice and order,” and this is made possible not by “Rule of Power” but by “Rule of Law.” International law and the Constitution of Japan both seek preservation of our peace, security and existence without the use of nuclear weapons.
When discussing the humanitarian impact of nuclear weapons, we cannot ignore the real facts of the Hiroshima and Nagasaki bombings and their legal consequences.