LEGALITY OF THE THREAT OR USE OF NUCLEAR WEAPONS
International Court of Justice, Advisory Opinion (8 July 1996) Gen. List No. 95
.....35 Int'l Legal Mat'ls 809 (1996). Permission to reprint granted by ILM © American Society of International Law

Testimony: Mr. Takekazu Kawamura, Ambassador, Director General for Arms Control
and Scientific Affairs, Ministry of Foreign Affairs (Japan). [For full text, click here, then click on CR/95/27--07 November 1995].

Mr. KAWAMURA: Thank you, Mr. President, for giving me the floor. Mr. President and Honourable Members of the Court, the Government of Japan has expressed its views on the use of nuclear weapons by submitting the written statements concerning the requests for advisory opinions.
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.....Mr. President, with their devastating power, nuclear weapons can in an instant take a tremendous toll in human life and deprive people of their local community structures; they can also cause the victims who survive an attack itself indescribable and lasting suffering due to atomic radiation and other lingering effects. Based on documents collected by the prefectures and cities of Hiroshima and Nagasaki, an overview of damage caused by atomic bombs dropped on both cities is as follows.
.....The yields of the atomic bombs detonated in Hiroshima on 6 August 1945 and in Nagasaki on 9 August 1945 were the equivalent of 15 kilotons and 22 kilotons of TNT respectively. The bomb blast produced a big fireball, followed by extremely high temperatures of some several million degrees centigrade, and extremely high pressure of several hundred thousand atmospheres. It also emitted a great deal of radiation. This fireball, which lasted for about 10 seconds, raised the ground temperature at the hypocentre to somewhere between 3,000 [degrees] C and 4,000 [degrees] C, and the heat caused the scorching of wood buildings over a radius of approximately 3 kilometres from the hypocentre. The number of houses damaged by the atomic bombs was 70,147 in Hiroshima and 18,409 in Nagasaki.
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.....The exact number of fatalities is now known, since documents are scarce. It is estimated, however, that the number of people who had died by the end of 1945 amounted to approximately 140,000 in Hiroshima and 74,000 in Nagasaki. The population of the cities at that time was estimated at 350,000 in Hiroshima and 240,000 in Nagasaki. The number of people who died of thermal radiation immediately after the bomb blast, on the same day or within a few days, is not clear. However, 90 to 100% of the people who were exposed to thermal radiation without any shield within 1 km of the hypocentre died within a week. The early mortality rates for the people who were within 1.5 km to 2 km of the hypocentre were 14% for people with a shield and 83% for people without a shield. In addition to direct injury from the bomb blast, death was caused by several interrelated factors such as being crushed or buried under buildings, injuries caused by splinters of glasses, radiation damage, food shortages or a shortage of doctors and medicine.
.....Over 320,000 people who survived but were affected by radiation suffer from various malignant tumors caused by radiation, including leukemia, thyroid cancer, breast cancer, lung cancer, gastric cancer, cataracts and a variety of other after-effects, more than half a century after the disaster. They are still undergoing medical examinations and treatments.
.....Mr. President, Japan, based on the tragic suffering of Hiroshima and Nagasaki, considers that nuclear weapons must never be used. Japan considers that the international community as a whole should cooperate to make sure that a similar tragedy never occurs again anywhere in the world. ...

[Court's Opinion.]
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30. However, the Court is of the view that the issue is not whether the treaties relating to the protection of the environment are or not applicable during an armed conflict, but rather whether the obligations stemming from these treaties were intended to be obligations of total restraint during military conflict.
.....The Court does not consider that the treaties in question could have intended to deprive a State of the exercise of its right of self-defence under international law because of its obligations to protect the environment. Nonetheless, States must take environmental considerations into account when assessing what is necessary and proportionate in the pursuit of legitimate military objectives. Respect for the environment is one of the elements that go to assessing whether an action is in conformity with the principles of necessity and proportionality.
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37. The Court will now address the question of the legality or illegality of recourse to nuclear weapons in the light of the provisions of the Charter relating to the threat or use of force.

38. The Charter contains several provisions relating to the threat and use of force. In Article 2, paragraph 4, the threat or use of force against the territorial integrity or political independence of another State or in any other manner inconsistent with the purposes of the United Nations is prohibited. That paragraph provides:

"All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any State, or in any other manner inconsistent with the Purposes of the United Nations."

.....This prohibition of the use of force is to be considered in the light of other relevant provisions of the Charter. In Article 51, the Charter recognizes the inherent right of individual or collective self-defence if an armed attack occurs. A further lawful use of force is envisaged in Article 42, whereby the Security Council may take military enforcement measures in conformity with Chapter VII of the Charter.

39. These provisions do not refer to specific weapons. They apply to any use of force, regardless of the weapons employed. The Charter neither expressly prohibits, nor permits, the use of any specific weapon, including nuclear weapons. A weapon that is already unlawful per se, whether by treaty or custom, does not become lawful by reason of its being used for a legitimate purpose under the Charter.

40. The entitlement to resort to self-defence under Article 51 is subject to certain constraints. Some of these constraints are inherent in the very concept of self defence. Other requirements are specified in Article 51.

41. The submission of the exercise of the right of self-defence to the conditions of necessity and proportionality is a rule of customary international law. As the Court stated in the case concerning Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America) (I.C.J. Reports 1986, p. 94, para. 176): "there is a specific rule whereby self-defence would warrant only measures which are proportional to the armed attack and necessary to respond to it, a rule well established in customary international law". This dual condition applies equally to Article 51 of the Charter, whatever the means of force employed.

42. The proportionality principle may thus not in itself exclude the use of nuclear weapons in self-defence in all circumstances. But at the same time, a use of force that is proportionate under the law of self-defence, must, in order to be lawful, also meet the requirements of the law applicable in armed conflict which comprise in particular the principles and rules of humanitarian law.
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44. Beyond the conditions of necessity and proportionality, Article 51 specifically requires that measures taken by States in the exercise of the right of self-defence shall be immediately reported to the Security Council; this article further provides that these measures shall not in any way affect the authority and responsibility of the Security Council under the Charter to take at any time such action as it deems necessary in order to maintain or restore international peace and security. These requirements of Article 51 apply whatever the means of force used in self defence.
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48. Some States put forward the argument that possession of nuclear weapons is itself an unlawful threat to use force. Possession of nuclear weapons may indeed justify an inference of preparedness to use them. In order to be effective, the policy of deterrence, by which those States possessing or under the umbrella of nuclear weapons seek to discourage military aggression by demonstrating that it will serve no purpose, necessitates that the intention to use nuclear weapons be credible. Whether this is a "threat" contrary to Article 2, paragraph 4, depends upon whether the particular use of force envisaged would be directed against the territorial integrity or political independence of a State, or against the Purposes of the United Nations or whether, in the event that it were intended as a means of defence, it would necessarily violate the principles of necessity and proportionality. In any of these circumstances the use of force, and the threat to use it, would be unlawful under the law of the Charter.
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51. Having dealt with the Charter provisions relating to the threat or use of force, the Court will now turn to the law applicable in situations of armed conflict. It will first address the question whether there are specific rules in international law regulating the legality or illegality of recourse to nuclear weapons per se; it will then examine the question put to it in the light of the law applicable in armed conflict proper, i.e. the principles and rules of humanitarian law applicable in armed conflict, and the law of neutrality.

52. The Court notes by way of introduction that international customary and treaty law does not contain any specific prescription authorizing the threat or use of nuclear weapons or any other weapon in general or in certain circumstances, in particular those of the exercise of legitimate self defence. Nor, however, is there any principle or rule of international law which would make the legality of the threat or use of nuclear weapons or of any other weapons dependent on a specific authorization. State practice shows that the illegality of the use of certain weapons as such does not result from an absence of authorization but, on the contrary, is formulated in terms of prohibition.

53. The Court must therefore now examine whether there is any prohibition of recourse to nuclear weapons as such; it will first ascertain whether there is a conventional prescription to this effect.

54. In this regard, the argument has been advanced that nuclear weapons should be treated in the same way as poisoned weapons. In that case, they would be prohibited under:

(a) the Second Hague Declaration of 29 July 1899, which prohibits "the use of projectiles the
.....object of which is the diffusion of asphyxiating or deleterious gases";
(b) Article 23 (a) of the Regulations respecting the laws and customs of war on land annexed
......to the Hague Convention IV of 18 October 1907, whereby "it is especially forbidden: ...
......to employ poison or poisoned weapons"; and
(c) the Geneva Protocol of 17 June 1925 which prohibits "the use in war of asphyxiating,
.....poisonous or other gases, and of all analogous liquids, materials or devices".

55. The Court will observe that the Regulations annexed to the Hague Convention IV do not define what is to be understood by "poison or poisoned weapons" and that different interpretations exist on the issue. Nor does the 1925 Protocol specify the meaning to be given to the term "analogous materials or devices". The terms have been understood, in the practice of States, in their ordinary sense as covering weapons whose prime, or even exclusive, effect is to poison or asphyxiate. This practice is clear, and the parties to those instruments have not treated them as referring to nuclear weapons.

56. In view of this, it does not seem to the Court that the use of nuclear weapons can be regarded as specifically prohibited on the basis of the above-mentioned provisions of the Second Hague Declaration of 1899, the Regulations annexed to the Hague Convention IV of 1907 or the 1925 Protocol (see paragraph 54 above).

57. The pattern until now has been for weapons of mass destruction to be declared illegal by specific instruments. The most recent such instruments are the Convention of 10 April 1972 on the Prohibition of the Development, Production and Stockpiling of Bacteriological (Biological) and Toxin Weapons and on their destruction which prohibits the possession of bacteriological and toxic weapons and reinforces the prohibition of their use and the Convention of 13 January 1993 on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on Their Destruction which prohibits all use of chemical weapons and requires the destruction of existing stocks. Each of these instruments has been negotiated and adopted in its own context and for its own reasons. The Court does not find any specific prohibition of recourse to nuclear weapons in treaties expressly prohibiting the use of certain weapons of mass destruction.

58. In the last two decades, a great many negotiations have been conducted regarding nuclear weapons; they have not resulted in a treaty of general prohibition of the same kind as for bacteriological and chemical weapons.
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60. Those States that believe that recourse to nuclear weapons is illegal stress that the conventions that include various rules providing for the limitation or elimination of nuclear weapons in certain areas (such as the Antarctic Treaty of 1959 which prohibits the deployment of nuclear weapons in the Antarctic, or the Treaty of Tlatelolco of 1967 which creates a nuclear-weapon-free zone in Latin America), or the conventions that apply certain measures of control and limitation to the existence of nuclear weapons (such as the 1963 Partial Test-Ban Treaty or the Treaty on the Non-Proliferation of Nuclear Weapons) all set limits to the use of nuclear weapons. In their view, these treaties bear witness, in their own way, to the emergence of a rule of complete legal prohibition of all uses of nuclear weapons.

61. Those States who defend the position that recourse to nuclear weapons is legal in certain circumstances see a logical contradiction in reaching such a conclusion. According to them, those Treaties, such as the Treaty on the Non-Proliferation of Nuclear Weapons, as well as Security Council resolutions 255 (1968) and 984 (1995) which take note of the security assurances given by the nuclear-weapon States to the non-nuclear-weapon States in relation to any nuclear aggression against the latter, cannot be understood as prohibiting the use of nuclear weapons, and such a claim is contrary to the very text of those instruments. For those who support the legality in certain circumstances of recourse to nuclear weapons, there is no absolute prohibition against the use of such weapons. The very logic and construction of the Treaty on the Non-Proliferation of Nuclear Weapons, they assert, confirm this. This Treaty, whereby, they contend, the possession of nuclear weapons by the five nuclear-weapon States has been accepted, cannot be seen as a treaty banning their use by those States; to accept the fact that those States possess nuclear weapons is tantamount to recognizing that such weapons may be used in certain circumstances. Nor, they contend, could the security assurances given by the nuclear-weapon States in 1968, and more recently in connection with the Review and Extension Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons in 1995, have been conceived without its being supposed that there were circumstances in which nuclear weapons could be used in a lawful manner. For those who defend the legality of the use, in certain circumstances, of nuclear weapons, the acceptance of those instruments by the different non-nuclear-weapon States confirms and reinforces the evident logic upon which those instruments are based.

62. The Court notes that the treaties dealing exclusively with acquisition, manufacture, possession, deployment and testing of nuclear weapons, without specifically addressing their threat or use, certainly point to an increasing concern in the international community with these weapons; the Court concludes from this that these treaties could therefore be seen as foreshadowing a future general prohibition of the use of such weapons, but they do not constitute such a prohibition by themselves.
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64. The Court will now turn to an examination of customary international law to determine whether a prohibition of the threat or use of nuclear weapons as such flows from that source of law. As the Court has stated, the substance of that law must be "looked for primarily in the actual practice and opinio juris [what States consider binding] of States" [citing ICJ precedent].

65. States which hold the view that the use of nuclear weapons is illegal have endeavoured to demonstrate the existence of a customary rule prohibiting this use. They refer to a consistent practice of non-utilization of nuclear weapons by States since 1945 and they would see in that practice the expression of an opinio juris on the part of those who possess such weapons.

66. Some other States, which assert the legality of the threat and use of nuclear weapons in certain circumstances, invoked the doctrine and practice of deterrence in support of their argument. They recall that they have always, in concert with certain other States, reserved the right to use those weapons in the exercise of the right to self-defence against an armed attack threatening their vital security interests. In their view, if nuclear weapons have not been used since 1945, it is not on account of an existing or nascent custom but merely because circumstances that might justify their use have fortunately not arisen.

67. The Court does not intend to pronounce here upon the practice known as the "policy of deterrence". ...

68. According to certain States, the important series of General Assembly resolutions, beginning with resolution 1653 (XVI) of 24 November 1961, that deal with nuclear weapons and that affirm, with consistent regularity, the illegality of nuclear weapons, signify the existence of a rule of international customary law which prohibits recourse to those weapons. According to other States, however, the resolutions in question have no binding character on their own account and are not declaratory of any customary rule of prohibition of nuclear weapons; some of these States have also pointed out that this series of resolutions not only did not meet with the approval of all of the nuclear-weapon States but of many other States as well.
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71. Examined in their totality, the General Assembly resolutions put before the Court declare that the use of nuclear weapons would be "a direct violation of the Charter of the United Nations"; and in certain formulations that such use "should be prohibited". The focus of these resolutions has sometimes shifted to diverse related matters; however, several of the resolutions under consideration in the present case have been adopted with substantial numbers of negative votes and abstentions; thus, although those resolutions are a clear sign of deep concern regarding the problem of nuclear weapons, they still fall short of establishing the existence of an opinio juris on the illegality of the use of such weapons.
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73. Having said this, the Court points out that the adoption each year by the General Assembly, by a large majority, of resolutions recalling the content of resolution 1653 (XVI), and requesting the member States to conclude a convention prohibiting the use of nuclear weapons in any circumstance, reveals the desire of a very large section of the international community to take, by a specific and express prohibition of the use of nuclear weapons, a significant step forward along the road to complete nuclear disarmament. The emergence, as lex lata, of a customary rule specifically prohibiting the use of nuclear weapons as such is hampered by the continuing tensions between the nascent opinio juris on the one hand, and the still strong adherence to the practice of deterrence on the other.
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85. Turning now to the applicability of the principles and rules of humanitarian law to a possible threat or use of nuclear weapons, the Court notes that doubts in this respect have sometimes been voiced on the ground that these principles and rules had evolved prior to the invention of nuclear weapons and that the Conferences of Geneva of 1949 and 1974-1977 which respectively adopted the four Geneva Conventions of 1949 and the two Additional Protocols thereto did not deal with nuclear weapons specifically. Such views, however, are only held by a small minority. In the view of the vast majority of States as well as writers there can be no doubt as to the applicability of humanitarian law to nuclear weapons.

86. The Court shares that view. Indeed, nuclear weapons were invented after most of the principles and rules of humanitarian law applicable in armed conflict had already come into existence; the Conferences of 1949 and 1974-1977 left these weapons aside, and there is a qualitative as well as quantitative difference between nuclear weapons and all conventional arms. However, it cannot be concluded from this that the established principles and rules of humanitarian law applicable in armed conflict did not apply to nuclear weapons. Such a conclusion would be incompatible with the intrinsically humanitarian character of the legal principles in question which permeates the entire law of armed conflict and applies to all forms of warfare and to all kinds of weapons, those of the past, those of the present and those of the future. In this respect it seems significant that the thesis that the rules of humanitarian law do not apply to the new weaponry, because of the newness of the latter, has not been advocated in the present proceedings. On the contrary, the newness of nuclear weapons has been expressly rejected as an argument against the application to them of international humanitarian law:

"In general, international humanitarian law bears on the threat or use of nuclear weapons as it does of other weapons.
.....International humanitarian law has evolved to meet contemporary circumstances, and is not limited in its application to weaponry of an earlier time. The fundamental principles of this law endure: to mitigate and circumscribe the cruelty of war for humanitarian reasons." (New Zealand, Written Statement, p. 15, paras. 63 64.)

.....None of the statements made before the Court in any way advocated a freedom to use nuclear weapons without regard to humanitarian constraints.
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90. Although the applicability of the principles and rules of humanitarian law and of the principle of neutrality to nuclear weapons is hardly disputed, the conclusions to be drawn from this applicability are, on the other hand, controversial.

91. According to one point of view, the fact that recourse to nuclear weapons is subject to and regulated by the law of armed conflict does not necessarily mean that such recourse is as such prohibited. As one State put it to the Court:

"Assuming that a State's use of nuclear weapons meets the requirements of self defence, it must then be considered whether it conforms to the fundamental principles of the law of armed conflict regulating the conduct of hostilities" (United Kingdom, Written Statement, p. 40, para. 3.44); "the legality of the use of nuclear weapons must therefore be assessed in the light of the applicable principles of international law regarding the use of force and the conduct of hostilities, as is the case with other methods and means of warfare" (United Kingdom, Written Statement, p. 75, para. 4.2(3)); and
....."The reality ... is that nuclear weapons might be used in a wide variety of circumstances with very different results in terms of likely civilian casualties. In some cases, such as the use of a low yield nuclear weapon against warships on the High Seas or troops in sparsely populated areas, it is possible to envisage a nuclear attack which caused comparatively few civilian casualties. It is by no means the case that every use of nuclear weapons against a military objective would inevitably cause very great collateral civilian casualties." (United Kingdom, Written Statement, p. 53, para. 3.70; see also United States of America, Oral Statement, CR 95/34, pp. 89-90.)

92. Another view holds that recourse to nuclear weapons could never be compatible with the principles and rules of humanitarian law and is therefore prohibited. In the event of their use, nuclear weapons would in all circumstances be unable to draw any distinction between the civilian population and combatants, or between civilian objects and military objectives, and their effects, largely uncontrollable, could not be restricted, either in time or in space, to lawful military targets. Such weapons would kill and destroy in a necessarily indiscriminate manner, on account of the blast, heat and radiation occasioned by the nuclear explosion and the effects induced; and the number of casualties which would ensue would be enormous. The use of nuclear weapons would therefore be prohibited in any circumstance, notwithstanding the absence of any explicit conventional prohibition. That view lay at the basis of the assertions by certain States before the Court that nuclear weapons are by their nature illegal under customary international law, by virtue of the fundamental principle of humanity.
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96. Furthermore, the Court cannot lose sight of the fundamental right of every State to survival, and thus its right to resort to self-defence, in accordance with Article 51 of the Charter, when its survival is at stake.
.....Nor can it ignore the practice referred to as "policy of deterrence", to which an appreciable section of the international community adhered for many years. The Court also notes the reservations which certain nuclear-weapon States have appended to the undertakings they have given, notably under the Protocols to the Treaties of Tlatelolco and Rarotonga, and also under the declarations made by them in connection with the extension of the Treaty on the Non-Proliferation of Nuclear Weapons, not to resort to such weapons.

97. Accordingly, in view of the present state of international law viewed as a whole, as examined above by the Court, and of the elements of fact at its disposal, the Court is led to observe that it cannot reach a definitive conclusion as to the legality or illegality of the use of nuclear weapons by a State in an extreme circumstance of self-defence, in which its very survival would be at stake.
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105. For these reasons,

THE COURT,
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(2) Replies in the following manner to the question put by the General Assembly:

A.Unanimously,
There is in neither customary nor conventional international law any specific authorization of the threat or use of nuclear weapons;

B. By eleven votes to three,
There is in neither customary nor conventional international law any comprehensive and universal prohibition of the threat or use of nuclear weapons as such;

C. Unanimously,
A threat or use of force by means of nuclear weapons that is contrary to Article 2, paragraph 4, of the United Nations Charter and that fails to meet all the requirements of Article 51, is unlawful;

D. Unanimously,
A threat or use of nuclear weapons should also be compatible with the requirements of the international law applicable in armed conflict, particularly those of the principles and rules of international humanitarian law, as well as with specific obligations under treaties and other undertakings which expressly deal with nuclear weapons;

E. By seven votes to seven, by the President's casting vote [thus, 8-7],
It follows from the above-mentioned requirements that 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;
.....However, in view of the current state of international law, and of the elements of fact at its disposal, the Court cannot conclude definitively whether the threat or use of nuclear weapons would be lawful or unlawful in an extreme circumstance of self-defence, in which the very survival of a State would be at stake....
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