Opinion of the
International Court of Justice

On the Legality of Nuclear Weapons

Moreover, it is the clear position of the Court that to contend that it should not deal with a question couched in abstract terms is "a mere affirmation devoid of any justification", and that "the Court may give an advisory opinion on any legal question, abstract or otherwise" (Conditions of Admission of a State to Membership in the United Nations (Article 4 of the Charter), Advisory Opinion, 1948, I.C.J. Reports 1947-1948, p. 61; see also Effect of Awards of Compensation Made by the United Nations Administrative Tribunal, Advisory Opinion, I.C.J. Reports 1954, p. 51; and Legal Consequences for States of the Continued Presence of South Africa in Namibia (South West Africa) notwithstanding Security Council Resolution 276 (1970), Advisory Opinion, I.C.J. Reports 1971, p. 27, para. 40).

Certain States have however expressed the fear that the abstract nature of the question might lead the Court to make hypothetical or speculative declarations outside the scope of its judicial function. The Court does not consider that, in giving an advisory opinion in the present case, it would necessarily have to write "scenarios", to study various types of nuclear weapons and to evaluate highly complex and controversial technological, strategic and scientific information. The Court will simply address the issues arising in all their aspects by applying the legal rules relevant to the situation.

16. Certain States have observed that the General Assembly has not explained to the Court for what precise purposes it seeks the advisory opinion. Nevertheless, it is not for the Court itself to purport to decide whether or not an advisory opinion is needed by the Assembly for the performance of its functions. The General Assembly has the right to decide for itself on the usefulness of an opinion in the light of its own needs.

Equally, once the Assembly has asked, by adopting a resolution, for an advisory opinion on a legal question, the Court, in determining whether there are any compelling reasons for it to refuse to give such an opinion, will not have regard to the origins or to the political history of the request, or to the distribution of votes in respect of the adopted resolution.

17. It has also been submitted that a reply from the Court in this case might adversely affect disarmament negotiations and would, therefore, be contrary to the interest of the United Nations. The Court is aware that, no matter what might be its conclusions in any opinion it might give, they would have relevance for the continuing debate on the matter in the General Assembly and would present an additional element in the negotiations on the matter. Beyond that, the effect of the opinion is a matter of appreciation. The Court has heard contrary positions advanced and there are no evident criteria by which it can prefer one assessment to another. That being so, the Court cannot regard this factor as a compelling reason to decline to exercise its jurisdiction.

18. Finally, it has been contended by some States that in answering the question posed, the Court would be going beyond its judicial role and would be taking upon itself a law-making capacity.

It is clear that the Court cannot legislate, and, in the circumstances of the present case, it is not called upon to do so. Rather its task is to engage in its normal judicial function of ascertaining the existence or otherwise of legal principles and rules applicable to the threat or use of nuclear weapons. The contention that the giving of an answer to the question posed would require the Court to legislate is based on a supposition that the present corpus juris is devoid of relevant rules in this matter. The Court could not accede to this argument; it states the existing law and does not legislate. This is so even if, in stating and applying the law, the Court necessarily has to specify its scope and sometimes note its general trend.

19. In view of what is stated above, the Court concludes that it has the authority to deliver an opinion on the question posed by the General Assembly, and that there exist no "compelling reasons" which would lead the Court to exercise its discretion not to do so.

An entirely different question is whether the Court, under the constraints placed upon it as a judicial organ, will be able to give a complete answer to the question asked of it. However, that is a different matter from a refusal to answer at all.

20. The Court must next address certain matters arising in relation to the formulation of the question put to it by the General Assembly. The English text asks: "Is the threat or use of nuclear weapons in any circumstance permitted under international law?" The French text of the question reads as follows: "Est-il permis en droit international de recourir la menace ou l'emploi d'armes nuclaires en toute circonstance?" It was suggested that the Court was being asked by the General Assembly whether it was permitted to have recourse to nuclear weapons in every circumstance, and it was contended that such a question would inevitably invite a simple negative answer.

The Court finds it unnecessary to pronounce on the possible divergences between the English and French texts of the question posed. Its real objective is clear: to determine the legality or illegality of the threat or use of nuclear weapons.

21. The use of the word "permitted" in the question put by the General Assembly was criticized before the Court by certain States on the ground that this implied that the threat or the use of nuclear weapons would only be permissible if authorization could be found in a treaty provision or in customary international law. Such a starting point, those States submitted, was incompatible with the very basis of international law, which rests upon the principles of sovereignty and consent; accordingly, and contrary to what was implied by use of the word "permitted", States are free to threaten or use nuclear weapons unless it can be shown that they are bound not to do so by reference to a prohibition in either treaty law or customary international law. Support for this contention was found in dicta of the Permanent Court of International Justice in the "Lotus" case that "restrictions upon the independence of States cannot . . . be presumed" and that international law leaves to States "a wide measure of discretion which is only limited in certain cases by prohibitive rules" (P.C.I.J., Series A, No. 10, pp. 18 and 19). Reliance was also placed on the dictum of the present Court in the case concerning Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America) that:
"in international law there are no rules, other than such rules as may be accepted by the State concerned, by treaty or otherwise, whereby the level of armaments of a sovereign State can be limited" (I.C.J. Reports 1986, p. 135, para. 269).

For other States, the invocation of these dicta in the "Lotus" case was inapposite; their status in contemporary international law and applicability in the very different circumstances of the present case were challenged. It was also contended that the above-mentioned dictum of the present Court was directed to the possession of armaments and was irrelevant to the threat or use of nuclear weapons.

Finally, it was suggested that, were the Court to answer the question put by the Assembly, the word "permitted" should be replaced by "prohibited".

22. The Court notes that the nuclear-weapon States appearing before it either accepted, or did not dispute, that their independence to act was indeed restricted by the principles and rules of international law, more particularly humanitarian law (see below, paragraph 86), as did the other States which took part in the proceedings.

Hence, the argument concerning the legal conclusions to be drawn from the use of the word "permitted", and the questions of burden of proof to which it was said to give rise, are without particular significance for the disposition of the issues before the Court.

23. In seeking to answer the question put to it by the General Assembly, the Court must decide, after consideration of the great corpus of international law norms available to it, what might be the relevant applicable law.

24. Some of the proponents of the illegality of the use of nuclear weapons have argued that such use would violate the right to life as guaranteed in Article 6 of the International Covenant on Civil and Political Rights, as well as in certain regional instruments for the protection of human rights. Article 6, paragraph 1, of the International Covenant provides as follows:
"Every human being has the inherent right to life. This right shall be protected by law. No one shall be arbitrarily deprived of his life."

In reply, others contended that the International Covenant on Civil and Political Rights made no mention of war or weapons, and it had never been envisaged that the legality of nuclear weapon was regulated by that instrument. It was suggested that the Covenant was directed to the protection of human rights in peacetime, but that questions relating to unlawful loss of life in hostilities were governed by the law applicable in armed conflict.

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. The Court recalls that, in Article II of the Convention genocide is defined as
"any of the following acts committed with intent to destroy, in whole or in part, a national, ethnical, racial or religious group, as such:

(a) Killing members of the group;

(b) Causing serious bodily or mental harm to members of the group;

(c) Deliberately inflicting on the group conditions of life calculated to being about its physical destruction in whole or in part;

(d) Imposing measures intended to prevent births within the group;

(e) Forcibly transferring children of the group to another group."

It was maintained before the Court that the number of deaths occasioned by the use of nuclear weapons would be enormous; that the victims could, in certain cases, include persons of a particular national, ethnic, racial or religious group; and that the intention to destroy such groups could be inferred from the fact that the user of the nuclear weapon would have omitted to take account of the well-known effects of the use of such weapons.

The Court would point out in that regard that the prohibition of genocide would be pertinent in this case if the recourse to nuclear weapons did indeed entail the element of intent, towards a group as such, required by the provision quoted above. In the view of the Court, it would only be possible to arrive at such a conclusion after having taken due account of the circumstances specific to each case.

27. In both their written and oral statements, some States furthermore argued that any use of nuclear weapons would be unlawful by reference to existing norms relating to the safeguarding and protection of the environment, in view of their essential importance.

Specific references were made to various existing international treaties and instruments. These included Additional Protocol I of 1977 to the Geneva Conventions of 1949, Article 35, paragraph 3, of which prohibits the employment of "methods or means of warfare which are intended, or may be expected, to cause widespread, long-term and severe damage to the natural environment"; and the Convention of 18 May 1977 on the Prohibition of Military or Any Other Hostile Use of Environmental Modification Techniques, which prohibits the use of weapons which have "widespread, long-lasting or severe effects" on the environment (Art. 1). Also cited were Principle 21 of the Stockholm Declaration of 1972 and Principle 2 of the Rio Declaration of 1992 which express the common conviction of the States concerned that they have a duty "to ensure that activities within their jurisdiction or control do not cause damage to the environment of other States or of areas beyond the limits of national jurisdiction". These instruments and other provisions relating to the protection and safeguarding of the environment were said to apply at all times, in war as well as in peace, and it was contended that they would be violated by the use of nuclear weapons whose consequences would be widespread and would have transboundary effects.

28. Other States questioned the binding legal quality of these precepts of environmental law; or, in the context of the Convention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification Techniques, denied that it was concerned at all with the use of nuclear weapons in hostilities; or, in the case of Additional Protocol I, denied that they were generally bound by its terms, or recalled that they had reserved their position in respect of Article 35, paragraph 3, thereof.

It was also argued by some States that the principal purpose of environmental treaties and norms was the protection of the environment in time of peace. It was said that those treaties made no mention of nuclear weapons. It was also pointed out that warfare in general, and nuclear warfare in particular, were not mentioned in their texts and that it would be destabilizing to the rule of law and to confidence in international negotiations if those treaties were now interpreted in such a way as to prohibit the use of nuclear weapons.

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.

This approach is supported, indeed, by the terms of Principle 24 of the Rio Declaration, which provides that:
"Warfare is inherently destructive of sustainable development. States shall therefore respect international law providing protection for the environment in times of armed conflict and cooperate in its further development, as necessary."

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 "[a]ppeals 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.

34. In the light of the foregoing the Court concludes that the most directly relevant applicable law governing the question of which it was seised, is that relating to the use of force enshrined in the United Nations Charter and the law applicable in armed conflict which regulates the conduct of hostilities, together with any specific treaties on nuclear weapons that the Court might determine to be relevant.

35. In applying this law to the present case, the Court cannot however fail to take into account certain unique characteristics of nuclear weapons.

The Court has noted the definitions of nuclear weapons contained in various treaties and accords. It also notes that nuclear weapons are explosive devices whose energy results from the fusion or fission of the atom. By its very nature, that process, in nuclear weapons as they exist today, releases not only immense quantities of heat and energy, but also powerful and prolonged radiation. According to the material before the Court, the first two causes of damage are vastly more powerful than the damage caused by other weapons, while the phenomenon of radiation is said to be peculiar to nuclear weapons. These characteristics render the nuclear weapon potentially catastrophic. The destructive power of nuclear weapons cannot be contained in either space or time. They have the potential to destroy all civilization and the entire ecosystem of the planet.

The radiation released by a nuclear explosion would affect health, agriculture, natural resources and demography over a very wide area. Further, the use of nuclear weapons would be a serious danger to future generations. Ionizing radiation has the potential to damage the future environment, food and marine ecosystem, and to cause genetic defects and illness in future generations.

36. In consequence, in order correctly to apply to the present case the Charter law on the use of force and the law applicable in armed conflict, in particular humanitarian law, it is imperative for the Court to take account of the unique characteristics of nuclear weapons, and in particular their destructive capacity, their capacity to cause untold human suffering, and their ability to cause damage to generations to come.

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.

International Court of Justice Opinion - Continued

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