Parere della Corte internazionale di Giustizia sulla liceità della minaccia o dell’uso delle armi nucleari / Legality of the threat or use of nuclear weapons. advisory opinion, (estratti) (1996)

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25. The Court observes that the protection of the International Covenant of Civil and Political Rights does not cease in times of war, except by operation of Article 4 of the Covenant whereby certain provisions may be derogated from in a time of national emergency. Respect for the right to life is not, however, such a provision. In principle, the right not arbitrarily to be deprived of one's life applies also in hostilities. The test of what is an arbitrary deprivation of life, however, then falls to be determined by the applicable lex specialis, namely, the law applicable in armed conflict which is designed to regulate the conduct of hostilities. Thus whether a particular loss of life, through the use of a certain weapon in warfare, is to be considered an arbitrary deprivation of life contrary to Article 6 of the Covenant, can only be decided by reference to the law applicable in armed conflict and not deduced from the terms of the Covenant itself.

26. Some States also contended that the prohibition against genocide, contained in the Convention of 9 December 1948 on the Prevention and Punishment of the Crime of Genocide, is a relevant rule of customary international law which the Court must apply [...].

29. The Court recognizes that the environment is under daily threat and that the use of nuclear weapons could constitute a catastrophe for the environment. The Court also recognizes that the environment is not an abstraction but represents the living space, the quality of life and the very health of human beings, including generations unborn. The existence of the general obligation of States to ensure that activities within their jurisdiction and control respect the environment of other States or of areas beyond national control is now part of the corpus of international law relating to the environment.

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. [...]

31. The Court notes furthermore that Articles 35, paragraph 3, and 55 of Additional Protocol I provide additional protection for the environment. Taken together, these provisions embody a general obligation to protect the natural environment against widespread, long-term and severe environmental damage; the prohibition of methods and means of warfare which are intended, or may be expected, to cause such damage; and the prohibition of attacks against the natural environment by way of reprisals.

These are powerful constraints for all the States having subscribed to these provisions.

32. General Assembly resolution 47/37 of 25 November 1992 on the Protection of the Environment in Times of Armed Conflict, is also of interest in this context. It affirms the general view according to which environmental considerations constitute one of the elements to be taken into account in the implementation of the principles of the law applicable in armed conflict: it states that "destruction of the environment, not justified by military necessity and carried out wantonly, is clearly contrary to existing international law". Addressing the reality that certain instruments are not yet binding on all States, the General Assembly in this resolution "appeals to all States that have not yet done so to consider becoming parties to the relevant international conventions."

In its recent Order in the Request for an Examination of the Situation in Accordance with Paragraph 63 of the Court's Judgment of 20 December 1974 in the Nuclear Tests (New Zealand v. France) Case, the Court stated that its conclusion was "without prejudice to the obligations of States to respect and protect the natural environment" (Order of 22 September 1995, I.C.J. Reports 1995, p. 306, para. 64). Although that statement was made in the context of nuclear testing, it naturally also applies to the actual use of nuclear weapons in armed conflict.

33. The Court thus finds that while the existing international law relating to the protection and safeguarding of the environment does not specifically prohibit the use of nuclear weapons, it indicates important environmental factors that are properly to be taken into account in the context of the implementation of the principles and rules of the law applicable in armed conflict.

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.

43. Certain States have in their written and oral pleadings suggested that in the case of nuclear weapons, the condition of proportionality must be evaluated in the light of still further factors. They contend that the very nature of nuclear weapons, and the high probability of an escalation of nuclear exchanges, mean that there is an extremely strong risk of devastation. The risk factor is said to negate the possibility of the condition of proportionality being complied with. The Court does not find it necessary to embark upon the quantification of such risks; nor does it need to enquire into the question whether tactical nuclear weapons exist which are sufficiently precise to limit those risks: it suffices for the Court to note that the very nature of all nuclear weapons and the profound risks associated therewith are further considerations to be borne in mind by States believing they can exercise a nuclear response in self-defence in accordance with the requirements of proportionality.

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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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.

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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.

74. The Court not having found a conventional rule of general scope, nor a customary rule specifically proscribing the threat or use of nuclear weapons per se, it will now deal with the question whether recourse to nuclear weapons must be considered as illegal in the light of the principles and rules of international humanitarian law applicable in armed conflict and of the law of neutrality.

75. A large number of customary rules have been developed by the practice of States and are an integral part of the international law relevant to the question posed. The "laws and customs of war" (as they were traditionally called) were the subject of efforts at codification undertaken in The Hague (including the Conventions of 1899 and 1907), and were based partly upon the St. Petersburg Declaration of 1868 as well as the results of the Brussels Conference of 1874. This "Hague Law" and, more particularly, the Regulations Respecting the Laws and Customs of War on Land, fixed the rights and duties of belligerents in their conduct of operations and limited the choice of methods and means of injuring the enemy in an international armed conflict. One should add to this the "Geneva Law" (the Conventions of 1864, 1906, 1929 and 1949), which protects the victims of war and aims to provide safeguards for disabled armed forces personnel and persons not taking part in the hostilities. These two branches of the law applicable in armed conflict have become so closely interrelated that they are considered to have gradually formed one single complex system, known today as international humanitarian law. The provisions of the Additional Protocols of 1977 give expression and attest to the unity and complexity of that law.

76. Since the turn of the century, the appearance of new means of combat has - without calling into question the longstanding principles and rules of international law - rendered necessary some specific prohibitions of the use of certain weapons, such as explosive projectiles under 400 grammes, dum-dum bullets and asphyxiating gases. Chemical and bacteriological weapons were then prohibited by the 1925 Geneva Protocol. More recently, the use of weapons producing "non-detectable fragments", of other types of "mines, booby traps and other devices", and of "incendiary weapons", was either prohibited or limited, depending on the case, by the Convention of 10 October 1980 on Prohibitions or Restrictions on the Use of Certain Conventional Weapons Which May Be Deemed to Be Excessively Injurious or to Have Indiscriminate Effects. The provisions of the Convention on "mines, booby traps and other devices" have just been amended, on 3 May 1996, and now regulate in greater detail, for example, the use of anti-personnel land mines.

77. All this shows that the conduct of military operations is governed by a body of legal prescriptions. This is so because "the right of belligerents to adopt means of injuring the enemy is not unlimited" as stated in Article 22 of the 1907 Hague Regulations relating to the laws and customs of war on land. The St. Petersburg Declaration had already condemned the use of weapons "which uselessly aggravate the suffering of disabled men or make their death inevitable". The aforementioned Regulations relating to the laws and customs of war on land, annexed to the Hague Convention IV of 1907, prohibit the use of "arms, projectiles, or material calculated to cause unnecessary suffering" (Art. 23).

78. The cardinal principles contained in the texts constituting the fabric of humanitarian law are the following. The first is aimed at the protection of the civilian population and civilian objects and establishes the distinction between combatants and non-combatants; States must never make civilians the object of attack and must consequently never use weapons that are incapable of distinguishing between civilian and military targets. According to the second principle, it is prohibited to cause unnecessary suffering to combatants: it is accordingly prohibited to use weapons causing them such harm or uselessly aggravating their suffering. In application of that second principle, States do not have unlimited freedom of choice of means in the weapons they use.

The Court would likewise refer, in relation to these principles, to the Martens Clause, which was first included in the Hague Convention II with Respect to the Laws and Customs of War on Land of 1899 and which has proved to be an effective means of addressing the rapid evolution of military technology. A modern version of that clause is to be found in Article 1, paragraph 2, of Additional Protocol I of 1977, which reads as follows:

"In cases not covered by this Protocol or by other international agreements, civilians and combatants remain under the protection and authority of the principles of international law derived from established custom, from the principles of humanity and from the dictates of public conscience."

In conformity with the aforementioned principles, humanitarian law, at a very early stage, prohibited certain types of weapons either because of their indiscriminate effect on combatants and civilians or because of the unnecessary suffering caused to combatants, that is to say, a harm greater than that unavoidable to achieve legitimate military objectives. If an envisaged use of weapons would not meet the requirements of humanitarian law, a threat to engage in such use would also be contrary to that law.

79. It is undoubtedly because a great many rules of humanitarian law applicable in armed conflict are so fundamental to the respect of the human person and "elementary considerations of humanity" as the Court put it in its Judgment of 9 April 1949 in the Corfu Channel case (I.C.J. Reports 1949, p. 22), that the Hague and Geneva Conventions have enjoyed a broad accession. Further these fundamental rules are to be observed by all States whether or not they have ratified the conventions that contain them, because they constitute intransgressible principles of international customary law.

80. The Nuremberg International Military Tribunal had already found in 1945 that the humanitarian rules included in the Regulations annexed to the Hague Convention IV of 1907 "were recognized by all civilized nations and were regarded as being declaratory of the laws and customs of war" (International Military Tribunal, Trial of the Major War Criminals, 14 November 1945 - 1 October 1946, Nuremberg, 1947, Vol. 1, p. 254).

81. The Report of the Secretary-General pursuant to paragraph 2 of Security Council resolution 808 (1993), with which he introduced the Statute of the International Tribunal for the Prosecution of Persons Responsible for Serious Violations of International Humanitarian Law Committed in the Territory of the Former Yugoslavia since 1991, and which was unanimously approved by the Security Council (resolution 827 (1993)), stated:

"In the view of the Secretary-General, the application of the principle nullum crimen sine lege requires that the international tribunal should apply rules of international humanitarian law which are beyond any doubt part of customary law. ...

The part of conventional international humanitarian law which has beyond doubt become part of international customary law is the law applicable in armed conflict as embodied in: the Geneva Conventions of 12 August 1949 for the Protection of War Victims; the Hague Convention (IV) Respecting the Laws and Customs of War on Land and the Regulations annexed thereto of 18 October 1907; the Convention on the Prevention and Punishment of the Crime of Genocide of 9 December 1948; and the Charter of the International Military Tribunal of 8 August 1945."

82. The extensive codification of humanitarian law and the extent of the accession to the resultant treaties, as well as the fact that the denunciation clauses that existed in the codification instruments have never been used, have provided the international community with a corpus of treaty rules the great majority of which had already become customary and which reflected the most universally recognized humanitarian principles. These rules indicate the normal conduct and behaviour expected of States.

83. It has been maintained in these proceedings that these principles and rules of humanitarian law are part of jus cogens as defined in Article 53 of the Vienna Convention on the Law of Treaties of 23 May 1969. The question whether a norm is part of the jus cogens relates to the legal character of the norm. The request addressed to the Court by the General Assembly raises the question of the applicability of the principles and rules of humanitarian law in cases of recourse to nuclear weapons and the consequences of that applicability for the legality of recourse to these weapons. But it does not raise the question of the character of the humanitarian law which would apply to the use of nuclear weapons. There is, therefore, no need for the Court to pronounce on this matter.

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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;

IN FAVOUR: President Bedjaoui; Vice-President Schwebel; Judges Oda, Guillaume, Ranjeva, Herczegh, Shi, Fleischhauer, Vereshchetin, Ferrari Bravo, Higgins;

AGAINST: Judges Shahabuddeen, Weeramantry, Koroma.

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,

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;

IN FAVOUR: President Bedjaoui; Judges Ranjeva, Herczegh, Shi, Fleischhauer, Vereschetin, Ferrari Bravo;

AGAINST: Vice-President Schwebel; Judges Oda, Guillaume, Shahabuddeen, Weeramantry, Koroma, Higgins.

F. Unanimously,

There exists an obligation to pursue in good faith and bring to a conclusion negotiations leading to nuclear disarmament in all its aspects under strict and effective international control.