Legal Restrictions on the Use of Nuclear Weapons
Marcus Glodek
September 5, 2000
Draft

This paper outlines a broad catalogue of legal instruments that restrict the use of nuclear weapons. The paper is largely based on Charles Moxley's analysis of the legality of nuclear weapons in Nuclear Weapons and International Law in the Post Cold War World ⁽¹⁾.

Self-Interest, Restraint, and the Law of Armed Conflict

The right to adopt means of injuring an enemy is not unlimited ⁽²⁾. The United States recognizes an extensive catalogue of legal restraints that govern the practices to which its military may resort in times of war. These restraints arise from international treaties and quasi-legal security assurances, the contents of the international law of armed conflict, as well as the domestic laws and policies of the United States itself.

It is in the vital interest of the United States to abide by the legal norms applicable in war. The law of armed conflict functions to protect the United States military and civilian population from excessive acts of violence by foreign powers. It introduces a minimum of stability and predictability into the otherwise uncontrollable reign of chaos and terror during war. It offers the prospect of greater fairness, reliability and approbation in subsequent, post-war international relations. Observance of the law of armed conflict figures as an essential element in a sustainable, long-term security policy.

The United States generally shares the view - as is widely reflected in its military manuals - that the law of armed conflict advances its security interests. For example, The Air Force Manual on International Law states that "the primary basis for the law, and the principal reason for its respect, is that it generally serves the self-interest of everyone subject to its commands" ⁽³⁾. In the words of the Chairman of the Joint Chiefs of Staff, "the Armed Forces of the United States have benefited [sic] from, and highly value, the humanitarianism encompassed by the laws of war. Many are alive today only because of the mutual restraint imposed by these rules, notwithstanding the fact that the rules have been applied imperfectly" ⁽⁴⁾.

The United States military recognizes that the law of armed conflict generally does not impose a significant military disadvantage on those who abide by its rules. The Naval/Marine Commander's Handbook indicates that the prohibitions contained in the law are designed to outlaw only those practices that were devoid of military utility in the first place: "The law of armed conflict is intended to preclude purposeless, unnecessary destruction of life and property and to ensure that violence is used only to defeat the enemy's military forces" ⁽⁵⁾. The Air Force Manual on International Law cites "efficiency" as one of the very reasons for which nations follow the rules of the law of armed conflict ⁽⁶⁾.

Apart from the protection of combatants and civilians during the course of war, the United States military recognizes that it is a crucial function of the law of armed conflict to facilitate the post-war restoration of peaceful relations between the belligerents. The Naval/Marine Commander's Handbook remarks that, "by preventing needless cruelty, the bitterness and hatred arising from armed conflict is lessened, and thus it is easier to restore an enduring peace. The legal and military experts who attempted to codify the laws of war more than a hundred years ago reflected this reality when they declared that the final object of an armed conflict is the 're-establishment of good relations and a more solid and lasting peace between the belligerent States'" ⁽⁷⁾. Similarly, the Air Force Manual on International Law recognizes the role of the law of armed conflict in "facilitating the restoration of peace and the friendly relations which must, at some point, inevitably accompany or follow the conclusion of hostilities" ⁽⁸⁾. Charles Moxley characterizes the law of armed conflict like this: "War is by nature limited and not total; in the fullness of time, it will give way to peace [...]. The purpose of war is to create an acceptable peace. The purpose of the law of war is to impose rationality on war so that the peace can be restored" ⁽⁹⁾.

The law of armed conflict is ultimately based on the insight that war is not an end in itself, but a means subservient to the establishment of peace. In the light of this purpose, it becomes apparent that the prohibitions contained in the law of armed conflict largely coincide with the restraints on the military operations of the United States which are imposed by military expediency, political prudence, and rational self-interest.

The Law of Armed Conflict and Nuclear Weapons

The use of nuclear weapons is restricted by several treaties, quasi-legal security assurances, the domestic laws of the United States and the international law of armed conflict. The United States fully acknowledges the applicability of international law to nuclear weapons: "The law of armed conflict governs the use of nuclear weapons - just as it governs the use of conventional weapons" ⁽¹⁰⁾. As the most lethal and destructive instruments that have ever been introduced into warfare, nuclear weapons impose an especially stringent mandate to foster awareness of their legal status and to safeguard against their unlawful deployment.

In the light of the paramount importance that an abuse of nuclear weapons be prevented, there is a strong case to be made that currently accepted legal norms already amount to a categorical prohibition - covering every conceivable circumstance - against their deployment. The case rests on a widely recognized legal principle which provides, under appropriate circumstances, for prophylactic prohibitions against types of practices which would in many particular instances prove to be illegal. Applied to nuclear weapons this means: If the vast majority of conceivable uses of nuclear weapons was illegal; if it was moreover difficult to distinguish between legal and illegal uses of nuclear weapons; and if it was so important to prevent illegal uses of nuclear weapons as to merit the prohibition of any use of them at all (even if some uses might otherwise have been acceptable); then currently accepted legal norms would give rise to prohibitive standards which would arguably render any conceivable use of nuclear weapons illegal per se ⁽¹¹⁾.

A finding of per se unlawfulness could have far-reaching, palpable consequences. Most immediately, the use of nuclear weapons would constitute a war crime ⁽¹²⁾, and those responsible for the use could be tried as criminals of war. Further, if the use of nuclear weapons was illegal, the threat of such use would likewise be illegal ⁽¹³⁾. Inasmuch as the preparedness to use nuclear weapons constitutes such a threat, the mere possession, let alone the maintenance and improvement, of nuclear weapons would arguably be illegal ⁽¹⁴⁾ (notwithstanding the distinctions that must be made between possession and preparedness to use nuclear weapons ⁽¹⁵⁾). Such a finding would further de-legitimize in the eyes of the public and the international community United States deterrence policies as essentially based on threatening illegal methods of warfare. Moreover, a strong case for the per se illegality of nuclear weapons would pre-empt the continuing quest among military planners for tactical uses of nuclear weapons outside the infamous framework of traditional deterrence policies. Most concretely, it would open up the possibility of domestic lawsuits against the institutions that develop, maintain or deploy the United States nuclear arsenal. Eventually, these developments could give rise to explicit prohibitions on nuclear weapons of the same kind as already govern other weapons of mass destruction.

Catalogue of Legal Restraints on the Use of Nuclear Weapons by the United StatesI. The nuclear weapon must be used only under extreme circumstances of self-defense, in which the very survival of the State is at stake.

The International Court of Justice ruled in the formal legal conclusions of its 1996 Advisory Opinion on the legality of the threat or use of nuclear weapons 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" ⁽¹⁶⁾. This opinion, however, is somewhat weakened by the clause that the Court could not "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" ⁽¹⁷⁾.

The Court's opinion at first glance appears to be equivocal as to whether "an extreme circumstance of self-defence, in which the very survival of a State would be at stake" constitutes the only exception to the otherwise absolute illegality of the threat or use of nuclear weapons; or whether the Court, in speaking of the general illegality of using nuclear weapons, means to make a weaker assertion to the effect that there are situations other than "an extreme circumstance of self-defence, in which the very survival of a State would be at stake", where the threat or use of nuclear weapons would be tolerable. The ambiguity is settled in the body of the Court's Advisory Opinion, where the Court explicitly states the circumstances of the problematic case for which "it cannot reach a definitive conclusion as to the legality or illegality of the use of nuclear weapons". According to the Court, the legal uncertainty arises solely in the case of "an extreme circumstance of self-defence, in which [...] the very survival [of a State] would be at stake" ⁽¹⁸⁾. Since the Court does not specify any other situation that might allow for lawful use of a nuclear weapon, "an extreme circumstance of self-defence, in which [...] the very survival [of a State] would be at stake", appears to constitute the one and only possible exception to the otherwise absolute illegality of the use of nuclear weapons.

The exact nature of the conceivable circumstance under which a State may actually claim its right to self-defense and use nuclear weapons has not been specified by the Court. On the one hand, the condition that there be a threat to the survival of the state suggests an extremely strong limitation on legal use to situations in which a State has tried unsuccessfully every other available means to defend itself and now faces nothing short of annihilation. On the other hand, the Court may be saying that for a State to claim its right to self-defense, the State merely needs to be in a "defensive posture", assuming that such a posture by definition involves a threat to a State's "survival". If this is the intended reading, it is noteworthy that even actions short of an actual attack may legitimize a nuclear response with an appeal to self-defense, since international law recognizes a right to anticipatory self-defense ⁽¹⁹⁾.

The Court's repeated assertions of a State's "fundamental right to self-defence" must not be taken to mean that a State's right to self-defense somehow transcends the prohibitive provisions contained in the international law of armed conflict. The body of the Court's Advisory Opinion itself contains language to the effect that, even in an extreme circumstance of self-defense, the principles of the international law of armed conflict are applicable to the use of a nuclear weapon: "Whether [the intention to use nuclear weapons] is a 'threat' [...] 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" ⁽²⁰⁾. Moreoever, several of the judges make clear in their individual opinions that even actions of self-defense are fully regulated by the legal restraints imposed by the international law of armed conflict. The president of the Court writes that "self-defense - if exercised in extreme circumstances in which the very survival of a State is in question - cannot engender a situation in which a State would exonerate itself from compliance with the 'intransgressible' norms of international humanitarian law" ⁽²¹⁾. Similarly, Judge Koroma states that the right to self-defense "exists within and not outside or above the law" ⁽²²⁾. In his individual opinion, Judge Ranjeva writes with regard to the principles of the international law of armed conflict: "These principles were intended to be applied in all cases of conflict without any particular consideration of the status of the parties to the conflict - whether they were victims or aggressors. If an exceptional authorization had been envisaged, the authors of the instruments could have referred to it, for example by incorporating limits or exceptions to the universal application". Judge Ranjeva concludes that "in the final analysis the Court does affirm that the exercise of legitimate self-defense cannot be envisaged outside the framework of the rules of law" ⁽²³⁾. The Vice-President of the Court Schwebel affirms (quoting from a legal authority): "There is not the slightest relation between the content of the right to self-defence and the claim that it is above the law and not amenable to evaluation by law" ⁽²⁴⁾.

In short: According to the World Court, the one and only possible exception to the otherwise absolute illegality of the use of nuclear weapons might be a use under "extreme circumstances of self-defense, in which the very survival of the State is at stake". The scope of actual conditions under which a State may claim this exception and use nuclear weapons is not specified by the Court. However, under any conceivable circumstances the right to use nuclear weapons is limited by the full range of legal restraints that arise from the international law of armed conflict.

II. The use of the nuclear weapon and its military objective must be well-defined, and must be known to appropriate decision-makers.

A qualified decision-maker must evaluate in advance the legality of the intended use of a nuclear weapon. Because the evaluation involves several juxtapositions the weapon's effects and the anticipated military objective, the use must be sufficiently well-defined to make it possible to assess the effects and the military objective of the use.

This means that the nuclear weapon must not be targeted at random, and that the nature of the target must be known in reasonable detail and with a reasonable degree of certainty. The time of the use must be decided upon, and the actual circumstances under which the use will take place at the designated time must be reasonably foreseeable. Target selection and analysis must be performed without excessive time or other circumstantial pressures to allow for reasonable care and deliberation. Targeting decisions must be made at high levels of command by decision-makers who are well-informed about the target, the effects of the use of the weapon and its military objective, and who are qualified and have been granted the authority to perform the necessary legal evaluations.

III. The nuclear weapon must not be used in a region where such use is prohibited by treaties or security assurances.

1. The nuclear weapon must not be used in a nuclear weapons free zone established by treaty.

The United States has signed several international treaties that limit the deployment of nuclear weapons ⁽²⁵⁾ in various regions of the world and outer space, including the Antarctic Treaty (1959), the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space (1967), the Treaty of Tlatelolco (1967), the Treaty on the Prohibition of the Emplacement of Nuclear Weapons on the Sea-Bed and the Ocean Floor (1971), the Treaty of Rarotonga (1985), and the Treaty of Pelindaba (1996). Upon ratification of the treaty of Pelindaba, the use of nuclear weapons will be unlawful on virtually all land areas in the Southern hemisphere of the world. Under the United States Constitution, treaties entered into by the United States are "the supreme Law of the Land" ⁽²⁶⁾, which means that they enjoy the binding status of domestic law, and supersede domestic legislation in the case of a legal conflict.

Under the Antarctic Treaty, the United States agrees that "any nuclear explosions [...] in Antarctica shall be prohibited" ⁽²⁷⁾.

Under the Treaty on the Principles Governing the Activities of States in the Exploration and Use of Outer Space, the United States agrees to the prohibition of "the testing of any type of weapons and the conduct of military maneuvers on celestial bodies". In particular, the United States agrees not to "place in orbit around the Earth any objects carrying nuclear weapons [...], install such weapons on celestial bodies, or station such weapons in outer space in any other manner" ⁽²⁸⁾.

Under Protocol 2 of the Treaty of Tlatelolco, the United States pledges not to use nuclear weapons within the territories of the following States: Antigua & Barbuda, Argentina, The Bahamas, Barbados, Belize, Bolivia, Brazil, Chile, Columbia, Costa Rica, Dominica, The Dominican Republic, Ecuador, El Salvador, Grenada, Guatemala, Haiti, Honduras, Jamaica, Mexico, Nicaragua, Panama, Paraguay, Peru, St. Lucia, St. Vincent / Grenadines, Suriname, Trinidad & Tobago, Uruguay, Venezuela ⁽²⁹⁾.

Under the Treaty on the Prohibition of the Emplacement of Nuclear Weapons on the Sea-Bed and the Ocean Floor, the United States agrees not to emplace on the ocean floor any nuclear weapons or facilities specifically designed for storing, testing or using nuclear weapons ⁽³⁰⁾.

Under Protocol 2 of the Treaty of Rarotonga, which was signed by the United States but has not yet been ratified, the United States pledges not to use nuclear weapons against the following States: Australia, The Cook Islands, Fiji, Kiribati, Nauru, New Zealand, Niue, Papua New Guinea, The Solomon Islands, Tonga, Tuvalu, Vanuatu, Western Samoa ⁽³¹⁾.

Under Protocol 1 of the Treaty of Pelindaba, which was signed by the United States but has not yet been ratified, the Unites States pledges not to use nuclear weapons against the following States: Algeria, Angola, Benin, Botswana, Burkina Faso, Burundi, Cameroon, Cape Verde, Central African Republic, Chad, Comoros, Congo, Cote d'Ivoire, Democratic Republic of Congo, Djibouti, Egypt, Eritrea, Ethiopia, Gabon, Gambia, Ghana, Guinea, Gunea-Bissau, Kenya, Lesotho, Liberia, Libya, Malawi, Mali, Mauritania, Mauritius, Morocco, Mozambique, Namibia, Niger, Nigeria, Rwanda, Sao Tome & Principe, Senegal, Seychelles, Sierra Leone, South Africa, Sudan, Swaziland, Tanzania, Togo, Tunisia, Uganda, Zambia, Zimbabwe ⁽³²⁾.

2. The nuclear weapon must not be used against a non-nuclear-weapons State that is a signatory to the Non-Proliferation Treaty and is neither allied nor associated with a nuclear weapons State in an attack against the United States or its allies.

On June 12, 1978, the United States Secretary of State declared that "the United States will not use nuclear weapons against any non-nuclear weapon state party to the NPT (Non-Proliferation Treaty) or any comparable internationally binding commitment not to acquire nuclear explosive devices, except in the case of an attack on the United States, its territories or armed forces, or its allies, by such a state allied to a nuclear weapon state, or associated with a nuclear weapon state in carrying out or sustaining an attack" ⁽³³⁾. The United States reaffirmed this position just before the 1995 Non-Proliferation Treaty Review and Extension Conference: "The United States reaffirms that it will not use nuclear weapons against non-nuclear-weapon States Parties to the Treaty on the Non-Proliferation of Nuclear Weapons except in the case of an invasion or any other attack on the United States, its territories, its armed forces or other troops, its allies, or on a State towards which it has a security commitment, carried out or sustained by such a non-nuclear-weapon State in association or alliance with a nuclear weapon State" ⁽³⁴⁾.

Under these security assurances, the United States effectively may not use nuclear weapons against any of the following States (unless the State is allied or associated with a nuclear power in an attack against the United States, or is not in good standing under the Non-Proliferation Treaty): Afghanistan, Australia, Austria, Barbados, Belgium, Benin, Bolivia, Botswana, Bulgaria, Burkina Faso, Cameroon, Canada, Chad, Colombia, Costa Rica, Cyprus, Denmark, Dominican Republic, Ecuador, Egypt, El Salvador, Ethiopia, Finland, The Gambia, Germany, Ghana, Greece, Guatemala, Haiti, Honduras, Hungary, Iceland, Indonesia, Iran, Iraq, Ireland, Italy, Ivory Coast, Jamaica, Japan, Jordan, Kenya, Republic of Korea, Kuwait, Laos, Lebanon, Lesotho, Liberia, Libya, Luxembourg, Madagascar, Malaysia, Maldive Islands, Mali, Malta, Mauritius, Mexico, Mongolia, Morocco, Nepal, Netherlands, New Zealand, Nicaragua, Nigeria, Norway, Panama, Paraguay, Peru, Philippines, Poland, Romania, San Marino, Senegal, Singapore, Somalia, Sri Lanka, Sudan, Swaziland, Sweden, Switzerland, Syrian Arab Republic, Taiwan, Togo, Trinidad & Tobago, Tunisia, Turkey, Uruguay, Venezuela, Yemen, Zaire ⁽³⁵⁾.

The determination whether or not a given State is in good standing under the Non-Proliferation Treaty is not at the discretion of the United States, but must be decided by the International Atomic Energy Commission. If the International Atomic Energy Commission finds that a State is in good standing under the Non-Proliferation Treaty, the security assurances given by the United States apply to that state without reservations ⁽³⁶⁾.

The United States so far has argued that its security assurances are merely politically binding, but not legally binding. However, on the grounds that the security assurances were given in a context where non-nuclear-weapon States relied on them in agreeing to an indefinite extension of the Non-Proliferation Treaty, and have been recognized as longstanding United States policy, they should be considered as legally binding. The legal significance of assurances given in connection with the extension of the Non-Proliferation Treaty is apparent from the following article from the Vienna Convention on the Law of Treaties, which has been signed, but has not yet been ratified by the United States: "The context for the purpose of the interpretation of a treaty shall comprise, in addition to the text, including its preamble and annexes: (a) any agreement relating to the treaty which was made between all the parties in connection with the conclusion of the treaty; (b) any instrument which was made by one or more parties in connection with the conclusion of the treaty and accepted by the other parties as an instrument related to the treaty" ⁽³⁷⁾. It is on the United States to formally recognize the legally binding nature of its security assurances ⁽³⁸⁾.

IV. The nuclear weapon must not be used in an unlawful act of reprisal.

Reprisals are acts which, "although illegal in themselves, may, under the specific circumstances of the given case, become justified because the guilty adversary has himself behaved illegally, and the action is taken in the last resort, in order to prevent the adversary from behaving illegally in the future" ⁽³⁹⁾.

However, somewhat contrary to the doctrine of reprisals, the United States military acknowledges that the obligations imposed by international law generally are not conditioned on reciprocity, and that the principle of reciprocity never applies to provisions protecting persons in treaties of a humanitarian character. The Air Force Manual on International Law states that "[t]he most important relevant treaties, the 1949 Geneva Conventions for the Protection of War Victims, are not formally conditioned on reciprocity. Parties to each Convention 'undertake to respect and to ensure respect and to ensure respect for the present Convention in all circumstances' under Article 1 common to the Conventions. The Vienna Convention On the Law of Treaties, Article 60(5), also recognizes that the general law on material breaches, as a basis for suspending the operation of treaties, does not apply to provisions protecting persons in treaties of a humanitarian character" ⁽⁴⁰⁾.

The United States recognizes on an operational level several explicit restrictions on the right to act in reprisal. According to the Air Force Manual on International Law, the following criteria, among others, must be met for a reprisal to be lawful: "(1) It must respond to grave and manifestly unlawful acts, committed by an adversary government, its military commanders or combatants for whom the adversary is responsible. (2) It must be for the purpose of compelling the adversary to observe the law of armed conflict ... Above all, [reprisals] are justifiable only to force an adversary to stop its extra-legal activity ... (3) There must be reasonable notice that reprisals be taken ... (4) Other reasonable means to secure compliance must be attempted. The victim of a violation in order to justify taking a reprisal must first exhaust other reasonable means of securing compliance ... [...] A reprisal must be proportional to the original violation. [...] Effective but disproportionate reprisals cannot be justified by the argument that only an excessive response will forestall further transgressions" ⁽⁴¹⁾

There are several targets against which reprisals are prohibited. The Air Force Commander's Handbook explains that "[u]nder the 1949 Geneva Conventions, reprisals may not be directed against hospitals, medical personnel, the sick and wounded, the shipwrecked, interned civilians, the inhabitants of occupied territory, and prisoners of war. [...] A Protocol to the 1949 Geneva Conventions would expand this list to include all civilians and civilian property on land, a [sic] well as cultural property and the natural environment. The United States signed the Protocol in 1977, but has not yet ratified it" ⁽⁴²⁾. The United States, in recognizing the illegality of reprisals against the targets that are protected under the Geneva Convention, implicitly acknowledges that reprisals can only be lawful insofar as they discriminate between legitimate and prohibited targets. It appears from these considerations that reprisals are governed by the principle of discrimination.

The United States recognizes that past reprisals have more often than not been inexpedient and unlawful. The Naval/Marine Commander's Handbook states that "[m]any attempted uses of reprisals in past conflicts have been unjustified either because the reprisals were not undertaken to deter violations by an adversary or were disproportionate to the preceding unlawful conduct" ⁽⁴³⁾. Aware of the escalation risks that are inherent in acts of reprisal, the United States has historically refrained from acts of reprisal: "Although reprisal is lawful when [the stated prerequisites] are met, there is always the risk that it will trigger retaliatory escalation (counter-reprisals) by the enemy. The United States has historically been reluctant to resort to reprisal for just this reason" ⁽⁴⁴⁾.

Given that nuclear weapons are vastly more destructive than conventional weapons, their use in reprisal against an attack with conventional weapons would in all likelihood violate the requirement of proportionality.

It is highly questionable if even an attack with weapons of mass destruction may legally be encountered with a nuclear reprisal, given the restraints imposed by the proportionality and especially the discrimination requirements. It is also unlikely that such a reprisal would satisfy the condition that it "prevent the adversary from behaving illegally in the future" ⁽⁴⁵⁾. Instead, under the actual circumstances under which a nuclear reprisal is likely to take place, it may well prompt a counter-reprisal from the adversary and only precipitate more unlawful actions along with the rapid escalation of the conflict. Even reprisals with low-yield nuclear weapons are likely to be unlawful, given the paramount escalation risks inherent in even a limited use of nuclear weapons. Judge Weeramantry states in his dissenting opinion that "[t]he sole justification, if any, for the doctrine of reprisals is that it is a means of securing legitimate warfare. With the manifest impossibility of that objective in relation to nuclear weapons, the sole reason for this alleged exception vanishes" ⁽⁴⁶⁾.

V. Based on an analysis of the likely, the less likely, and the unpredictable effects of the use of the nuclear weapon, and an assessment of the anticipated military objective, the effects and the risks associated with the use of the weapon must not violate the international law of armed conflict, in particular the principles of necessity, discrimination, and neutrality and proportionality.

The United States recognizes on an operational level the binding character of the international law of armed conflict. According to The Air Force Manual on International Law, "state and federal courts have declared international law to be part of the law of the land." ⁽⁴⁷⁾. The manual also states that the United States is bound to follow customary international law "not because a treaty requires it, but because international law imposes obligations on all states" ⁽⁴⁸⁾. The International Court of Justice remarks on the position of the United States and the other nuclear-weapon states that "the nuclear-weapon States appearing before [the Court] either accepted, or did not dispute, that their independence to act was indeed restricted by the principles and rules of international law" ⁽⁴⁹⁾.

The applicability of the law of armed conflict to nuclear weapons has been recognized by the United States in its statements before the International Court of Justice: "The law of armed conflict governs the use of nuclear weapons - just as it governs the use of conventional weapons" ⁽⁵⁰⁾.

The international law of armed conflict can be organized according to a number of legal principles, which include the principles of proportionality, necessity, moderation, discrimination, civilian immunity, neutrality, humanity, and the protection of the environment. There also are several specific prohibitions such as limit target area bombing, and outlaw poisonous, chemical and bacteriological weapons ⁽⁵¹⁾. In order to set forth the concrete prohibitions contained in the international law of armed conflict, it should suffice - given the overlaps among the various legal principles - to discuss the principles of proportionality, necessity, discrimination and neutrality.

1. The effects and the risks to combatants, civilians or the environment associated with the use of the weapon must not be disproportionate to the value of the anticipated military objective.

The United States specifically recognizes the principle of proportionality on an operational level in its military manuals. For example, the Air Force Manual on International Law states that "the principle of proportionality is a well recognized legal limitation on weapons or methods of warfare which requires that injury or damage to legally protected interests must not be disproportionate to the legitimate military advantages secured by the weapons" ⁽⁵²⁾.

The principle of proportionality prohibits disproportionate incidental injury to civilian persons or damage to civilian objects, and moreover extends to the protection of combatants, one's own as well as the adversary's ⁽⁵³⁾. The principle of proportionality also applies to the environmental damage caused by a nuclear weapon: "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" ⁽⁵⁴⁾.

An analysis of the use of a nuclear weapon in the light of the principle of proportionality includes considerations as to the value of the anticipated military objective; the overall military advantage to the user of accomplishing the military objective; the likelihood that the weapon will actually accomplish the military objective; the severity of the likely injury and destruction that will ensue from the use of the weapon; and the risks of incurring less likely or unpredictable injury and destruction from the use of the weapon.

2. The effects or the risks to combatants, civilians or the environment associated with the use of the weapon must not be unnecessary to accomplish the military objective.

The United States specifically recognizes the principle of necessity on an operational level in its military manuals. For example, The Naval/Marine Commander's Handbook states that international law seeks to prevent "unnecessary suffering and destruction" and thereby permits "only that degree and kind of force required for the partial or complete submission of the enemy with a minimum expenditure of time, life and physical resources" ⁽⁵⁵⁾.

The principle of necessity prohibits unnecessary incidental injury to civilian persons or damage to civilian objects, and moreover extends to the protection of combatants, one's own as well as the adversary's ⁽⁵⁶⁾. The principle of necessity also applies to the environmental damage from the use of a nuclear weapon: "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" ⁽⁵⁷⁾.

An analysis of the use of a nuclear weapon in the light of the principle of necessity includes considerations as to the exigencies of the anticipated military objective; the overall military advantage to the user of accomplishing the military objective; the likelihood that the weapon will actually accomplish the military objective; the severity of the likely injury and destruction that will result from the use of the weapon; the risks of incurring less likely or unpredictable injury or destruction from the use of the weapon; and the availability of a conventional weapon which could reasonably be expected to accomplish the military objective with less devastating or risky effects.

3. The effects and the risks associated with the use of the weapon must not violate the principle of discrimination between civilian and military targets.

The United States specifically recognizes the principle of discrimination on an operational level in its military manuals. For example, The Air Force Commander's Handbook states that weapons that are "incapable of being controlled enough to direct them against a military objective" are unlawful" ⁽⁵⁸⁾. The Air Force Manual on International Law defines indiscriminate weapons as those which are "incapable of being controlled, through design or function," such that they "cannot, with any degree of certainty, be directed at military objectives" ⁽⁵⁹⁾.

The United States acknowledges that the principle of discrimination applies to a wide range of effects of a weapon. For example, the Air Force Manual on International Law states that indiscriminate weapons include those which, while they must be directed at military objectives with a reasonable degree of reliability and accuracy, "may have otherwise uncontrollable effects so as to cause disproportionate civilian injuries or damage" ⁽⁶⁰⁾. The manual explains that "uncontrollable" refers to effects "which escape in time or space from the control of the user as to necessarily create risks to civilian persons or objects excessive in relation to the military advantage anticipated" ⁽⁶¹⁾. The principle of discrimination presumably extends to the effects of a nuclear weapon on future generations, and requires that the genetic damage to the children of both combatants and civilians be taken into account. Judge Weeramantry comments in his dissenting opinion on the "intergenerational effects" of nuclear weapons: "Apart from damage to the environment which successive generations will inherit far into the future, radiation also causes genetic damage and will result in a crop of deformed and defective offspring, as proved in Hiroshima and Nagasaki" ⁽⁶²⁾.

An analysis of the use of a nuclear weapon in the light of the principle of discrimination includes considerations as to whether the weapon would actually be used against a military target; whether the injury among non-military persons would not be so excessive that it could not be considered unintended or collateral by any standard; considerations as to the severity of the likely injury and destruction of civilian targets from the use of the weapon, weighted against the weapon's effectiveness against the military target; considerations as to the risks of incurring less likely or unpredictable injury and destruction of civilian targets, weighted against the likelihood that the weapon will actually accomplish the military objective; and the availability of a conventional weapon which could reasonably be expected to accomplish the military objective with less indiscriminate effects.

4. The effects and the risks associated with the use of the weapon must not cause injury among the population, or destruction to the environment in a neutral state.

The United States specifically recognizes the principle of neutrality on an operational level in its military manuals. For example, The Naval/Marine Commander's Handbook states that a neutral state is entitled to "inviolability" and that, under customary international law, all acts of hostility are prohibited in "neutral territory, including neutral lands, neutral waters, and neutral airspace" ⁽⁶³⁾. The Air Force Manual on International Law acknowledges that injury to a neutral state's civilian population violates its right to inviolability, noting that the uncontrollable and unlawful effects of a weapon "may include injury to the civilian population of other states" ⁽⁶⁴⁾.

However, in its arguments before the World Court, the United States departed from the stringent standard of "inviolability", and argued that the scope of the principle of neutrality was not absolute. The United States claimed that there was no "broad guarantee to neutral States of immunity from the effects of war, whether economic or environmental", and that the United States was "aware of no case in which a belligerent has been held responsible for collateral damage to neutral territory for lawful acts of war committed outside that territory" ⁽⁶⁵⁾. The United States attorney stated before the Court that "the principle of neutrality has never been understood to guarantee neutral States absolute immunity from the effects of armed conflict" ⁽⁶⁶⁾.

The World Court, quoting the State of Nauru, takes the position that "the principle of neutrality applies with equal force to transborder incursions of armed forces and to the transborder damage caused to a neutral State by the use of a weapon in a belligerent State" ⁽⁶⁷⁾. Still, the Court does not specify what degree of injury or destruction in a neutral state would amount to a violation of the principle of neutrality.

An analysis of the use of a nuclear weapon in the light of the principle of neutrality includes considerations as to the distance of the weapon's target from the borders of neutral states; the likely injury and destruction within neutral states from the use of the weapon; the risks of incurring less likely or unpredictable injury and destruction in neutral states; the likelihood that a given percentage of weapons, or any single weapon, would be misdelivered to a neutral state; and the availability of a conventional weapon which could reasonably be expected to accomplish the military objective with less severe effects on neutral states.

VI. Given the military and political tensions under which the nuclear weapons are used, the use of the weapons must not lead to the escalation of the conflict, insofar as escalation would precipitate excessive or catastrophic levels of injury and destruction.

The broad guidelines set forth in United States military manuals contain an implicit obligation on the user of nuclear weapons to legally evaluate the danger that the proposed use may trigger the escalation of the conflict to excessive and unlawful levels. The Naval/Marine Commander's Handbook states that a commander, in determining whether a proposed military operation would be acceptable or whether an alternate method of attack should be adopted, "must decide [the matter] in light of all the facts known or reasonably available to him" ⁽⁶⁸⁾. The obligation to consider all the facts suggests that the evaluation must be so comprehensive as to include the possibility of excessive escalation. Similarly, the Naval/Marine Commander's Handbook states that the commander's evaluations must be based on "an honest and reasonable estimate of the facts available to him" ⁽⁶⁹⁾. Again, there is an implicit obligation to make an estimate of the possibility of escalation.

The user of a nuclear weapon is not absolved from the legal responsibility for preventing excessive escalation by the circumstance that the enemy may likewise be engaging in escalatory practices. Even where the enemy purposefully assumes a posture that makes it difficult to wage a lawful military operation against him, the obligation to refrain from unlawful strikes does not lose its force . To illustrate this point, The Air Force Commanders Handbook proposes a situation where "the enemy has deliberately used civilians to shield military objectives" ⁽⁷⁰⁾; according to the manual, the commander must even then perform a legal analysis of the intended strike. This means: Although both sides in a conflict may be held accountable for escalation once it has occurred, this circumstance does not absolve either side from its legal obligation to refrain from escalatory practices wherever the ultimate consequences would be unlawful.

Escalatory practices can scarcely be legitimized by an appeal to military necessity or proportionality. "It is a generally recognized principle of law that an actor may not justify the use of a level of force when the actor himself created the necessity" ⁽⁷¹⁾. This means: If a State initiates or precipitates escalation through the use of a nuclear weapon, then further nuclear strikes by that State - even though they may seem necessary or proportional within the logic of escalation - will not be any more acceptable. For the State has itself created the necessity for the subsequent nuclear uses through engaging in escalatory practices, and the overall devastation from the war is presumably unnecessary and disproportionate in the light of the original military objective.

The United States has acknowledged that the possibility of escalation is relevant to the legal analysis. This is apparent from the United States' discussion of escalation in its arguments before the World Court ⁽⁷²⁾. However, the United States did not recognize before the Court that even the risk of escalation constitutes a basis for legal restraints. Instead, the United States indicated that only the prospect of inevitable escalation is legally relevant. The United States lawyer stated in his oral argument before the World Court: "The argument that international law prohibits, in all cases, the use of nuclear weapons appears to be premised on the incorrect assumption that every use of every type of nuclear weapons will necessarily share certain characteristics which contravene the law of armed conflict. Specifically, it appears to be assumed that any use of nuclear weapons would inevitably escalate into a massive strategic nuclear exchange, resulting automatically in the deliberate destruction of the population centers of the opposing sides" ⁽⁷³⁾.

Contrary to the United States' argument, even the mere risk of escalation carries legal significance. Legal systems throughout the world, including the domestic law of the United States, recognize that criminal liability may arise not only where the consequences of an action would inevitably violate the law, but also where there is merely a substantial risk of a violation. For example, risks play an important role in the United States Model Penal Code's definition of reckless actions: "A person acts recklessly ...when he consciously disregards a substantial and unjustifiable risk that the ... element [of an offense] exists or will result from his conduct" ⁽⁷⁴⁾. Even some of the United States' statements before the World Court reflect the recognition - contrary to the predominant line of argument - that the risks associated with nuclear weapons are relevant to the legal analysis: "Whether an attack with nuclear weapons would be disproportionate depends [...] on [...] the magnitude of the risk to civilians" ⁽⁷⁵⁾.

As to the legal valuation of escalation risks, international law may give rise to legal prohibitions against the use of nuclear weapons if a substantial majority of conceivable uses of nuclear weapons would result in unlawful escalation; if it was difficult to distinguish between uses that would result in unlawful escalation and uses that would remain within the boundaries of lawfulness; or if it was of paramount importance that unlawful escalation be prevented ⁽⁷⁶⁾. Given these considerations, the escalation risks inherent in the use of nuclear weapons constitute an important ground for legal restraints.

Escalation risks are especially pertinent where a nuclear weapon is used against a State that may respond with weapons of mass destruction, or is associated with a state that may do so. Charles Moxley identifies the following elements of risk ⁽⁷⁷⁾: The political circumstances of the use of the nuclear weapon may be so volatile as to provoke a response with weapons of mass destruction; the adversary or its associate may perceive even a limited nuclear strike as an all-out strategic nuclear attack and respond with weapons of mass destruction; or the adversary may perceive even a limited nuclear strike as an abandonment of restraint and respond with weapons of mass destruction.; the nuclear strike may prompt the enemy to deploy its own weapons of mass destruction before they can be destroyed by a second strike; or the nuclear strike may prompt the adversary to destroy United States nuclear weapons with weapons of mass destruction before they can be used in a second strike; finally, the adversary may respond with weapons of mass destruction prompted by despair or suicidal vengefulness ⁽⁷⁸⁾.

The United States on an operational level fully acknowledges there are immense escalation risks inherent in the use of nuclear weapons. The Doctrine for Joint Theater Nuclear Operations notes that "there may be rapid escalation" once strikes begin to affect "the forces available for nuclear deployment" ⁽⁷⁹⁾. Similarly, the Joint Pub 3-12, Doctrine for Joint Nuclear Operations by the Joint Chiefs of Staff states that "there can be no assurances that a conflict involving weapons of mass destruction could be controllable or would be of short duration" ⁽⁸⁰⁾.

VII. The use of the nuclear weapon must not be analogous to methods of warfare that have previously been deemed unlawful.

The United States specifically recognizes the principle of analogy on an operational level in its military manuals. For example, The Air Force Manual on International Law states that "[a] new weapon or method of warfare may be illegal, per se, if it is restricted by international law including treaty or international custom. The issue is resolved, or attempted to be resolved, by analogy to weapons or methods previously determined to be lawful or unlawful" ⁽⁸¹⁾. An example for the application of the principle of analogy is the law of air warfare, which "must be derived from general principles, extrapolated from the law affecting land or sea warfare, or derived from other sources including the practice of states reflected in a wide variety of sources. Yet the US is party to numerous treaties which affect aerial operations either directly or by analogy" ⁽⁸²⁾.

Appealing to the principle of analogy, several states argued before the International Court of Justice that, on account of the radiation effects of nuclear weapons, they should be treated in the same way as poisoned weapons ⁽⁸³⁾, which are illegal under several international conventions. The World Court acknowledged that the Geneva Protocol of 17 June 1925 prohibits "the use in war of asphyxiating, poisonous or other gases, and of all analogous liquids, materials or devices" ⁽⁸⁴⁾. But the Court ultimately found that "it does not seem that nuclear weapons can be regarded as specifically prohibited" ⁽⁸⁵⁾ under the Protocol. However, the Court's opinion leaves open the possibility that prohibitions against poisonous weapons apply, not specifically, but by analogy, to nuclear weapons.

The United States, while acknowledging the toxicity of radiation, argued before the World Court that the prohibition of poisoned weapons does not extend to nuclear weapons: "[The prohibition on poisoned weapons] does not prohibit nuclear weapons, which are designed to injure or cause destruction by means other than poisoning the victim, even though nuclear explosions may also create toxic radioactive byproducts" ⁽⁸⁶⁾. The United States' argument is apparently based on the claim that the that radiation should be treated as an unintended side-effect of nuclear weapons. The Naval/Marine Commander's Handbook argues along the same lines: "It has been contended that nuclear radiation is sufficiently comparable to a poison gas to justify extending the 1925 Gas Protocol's prohibition to include the use of nuclear weapons. However, this ignores the explosive, heat and blast effects of a nuclear burst, and disregards the fact that fall-out is a by-product which is not the main or most characteristic feature of the weapon. The same riposte is available to meet an argument that the use of nuclear weapons would violate the prohibition on the use of poisoned weapons, set out in article 23(a) of the Hague Regulations" ⁽⁸⁷⁾.

In these statements, the United States fails to appreciate the preposterous degree of injury and destruction that can result from nuclear radiation. Even if radiation effects could be regarded as collateral by-products of nuclear explosions, they would still have to conform with such legal principles as proportionality, necessity, discrimination and neutrality. However, beyond a certain level of suffering and devastation, it is repugnant to reason to characterize foreseeable injury and destruction as a "by-product", and it is extremely unlikely that the radiation effects of nuclear weapons would be limited enough to pass as "incidental", "unintended" or "collateral" by any standard. But if radiation effects cannot be regarded as incidental, the analogy between nuclear and poisoned weapons appears to be valid.

In connection with the principle of analogy, it should be noted that many of the arguments that were advanced before the World Court for the legality of high-precision low-yield nuclear weapons are theoretically also applicable to chemical or bacteriological weapons. If - as the United States argued - the effects of low-yield nuclear weapons can be contained and directed at military targets with accuracy and reliability, this may also seem true for the use of small doses of chemical or biological agents. But notwithstanding the fact that there may be limited uses of chemical and bacteriological weapons at least in the abstract, they have been outlawed as weapons of mass destruction. The unlawfulness of even small doses of bacteriological weapons together with the principle of analogy support the case that low-yield nuclear weapons would likewise be illegal.

Sources:

[1] Legality of the Threat or Use of Nuclear Weapons. International Court of Justice, General List at pt. VI, No.95 (July 8, 1996).

[2] Moxley, Charles J., Jr. Nuclear Weapons and International Law in the Post Cold War World. Lanham: Austin & Winfield, 2000.

[3] Antarctic Treaty. December 1, 1959.

[4] Treaty On Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies. January 27, 1967.

[5] Treaty for the Prohibition of Nuclear Weapons in Latin America. April 1, 1968.

[6] Treaty On the Prohibition of the Emplacement of Nuclear Weapons and Other Weapons of Mass Destruction on the Seabed and the Ocean Floor and in the Subsoil Thereof. February 11, 1974.

[7] South Pacific Nuclear Free Zone Treaty. August 6, 1985.

[8] African Nuclear-Weapon-Free Zone Treaty. April 11, 1996.

[9] Arms Control and Disarmament Agreements: Texts and Histories of the Negotiations. United States Arms Control and Disarmament Agency. 1996.

[10] Burroughs, John. US Presidential Decision Directive 60 versus Pledges of Non-Use of Nuclear Weapon Made to Non-Nuclear Weapon States. Available at http://www.lcnp.org/disarmament/nato.htm.

[11] Treaty on the Non-Proliferation of Nuclear Weapons. July 1, 1968.

1. Cf [2].

2. Cf. The Naval/Marine Commander's Handbook, at 8-1 n.2. Quoted in [2], p. 39.

3. The Air Force Manual on International Law, at 1-11. Quoted in [2], p. 29.

4. The Air Force Manual on International Law, at 1-9. Quoted in [2], p. 29.

5. The Naval/Marine Commander's Handbook, at 5-7 n.7. Quoted in [2], p. 28.

6. Quoted in [2], p.32.

7. The Naval/Marine Commander's Handbook, at 5-7 n.7. Quoted in [2], p. 29.

8. The Air Force Manual on International Law, at 1-5. Quoted in [2], p. 29.

9. [2], p. 28.

10. United States of America, CR 94/34, p. 85. Quoted in [1], p. 30.

11. Cf. [2], p. 255.

12. Cf. [2], p. 101.

13. Cf. Advisory Opinion 47. [1], p. 19.

14. Cf. Advisory Opinion 48. [1], p. 19.

15. Cf. Dissenting Opinion of Judge Weeramantry. [1], p. 78.

16. Advisory Opinion. [1], pp. 35-36.

17. Advisory Opinion. [1], pp. 35-36.

18. Advisory Opinion. [1], p. 33.

19. Cf. [2], pp. 174-175.

20. Advisory Opinion. [1], p. 19.

21. Declaration of President Bedjaoui. [1], p. 5. Translated at [2], p.176.

22. Dissenting Opinion of Judge Koroma. [1], p. 4.

23. Individual Opinion of Judge Ranjeva. [1], pp. 6-7. Translated at [2], pp. 178-179.

24. Dissenting Opinion of Vice-President Schwebel. [1], p. 8.

25. Advisory Opinion. [1], pp. 21-22.

26. United States Constitution, Article VI, cl. 2. Quoted in [2], p. 31.

27. Article V, [3].

28. Article IV, [4].

29. Article 1a; Additional Protocol 2, Article 2, [5].

30. Article 1, [6].

31. Protocol 2, Article 2, [7].

32. Protocol 1, Article I, [8].

33. [9], p. 68.

34. [10], p. 2.

35. Cf. [11].

36. Cf. [10], pp. 3-4.

37. Vienna Convention on the Law of Treaties. Quoted in Footnote 1. [2], p. 275.

38. [10], pp. 3-4.

39. The Air Force Manual on International Law, at 10-3; 10-6 n.12. Quoted in [2], p. 89.

40. The Air Force Manual on International Law, at 10-1. Quoted in [2], p. 88.

41. The Air Force Manual on International Law, at 10-7c. Quoted in [2], p. 90.

42. The Air Force Commander's Handbook, at 8-2. Quoted in [2], p. 92-93.

43. The Naval/Marine Commander's Handbook, at 6-25 n. 46. Quoted in [2], p. 91-92.

44. The Naval/Marine Commander's Handbook, at 6-25. Quoted in [2], p. 92.

45. The Air Force Manual on International Law, at 10-3; 10-6 n.12. Quoted in [2], p. 89.

46. Dissenting Opinion of Judge Weeramantry, at 80. Quoted in [2].

47. The Air Force Manual on International Law, at 1-5, n.26. Quoted in [2], p. 31.

48. The Air Force Manual on International Law, at 1-5, n.26. Quoted in [2], p. 31.

49. Advisory Opinion. [1], p. 13.

50. United States of America, CR 94/34, p.85. Quoted in [1], p. 30.

51. Cf. [2], pp. v-vi.

52. The Air Force Manual On International Law at 6-1 to 6-2. Quoted in [2] p. 41.

53. Cf. [2], p. 41.

54. Advisory Opinion. [1], p. 15.

55. The Naval/Marine Commander's Handbook at 5-2 to 5-4. Quoted in [2], p. 54

56. Cf. [2], p. 52.

57. Advisory Opinion, [1], p. 15.

58. Air Force Commander's Handbook at 5-1. Quoted in [2], p. 64.

59. The Air Force Manual on International Law at 6-3. Quoted in [2], p. 64.

60. The Air Force Manual on International Law at 6-3. Quoted in [2], p. 66.

61. The Air Force Manual on International Law. Quoted in [2], p. 66.

62. Dissenting Opinion of Judge Weeramantry. [1], p.21.

63. The Naval/Marine Commander's Handbook at 7-3, 7-16. Quoted in [2], p. 700.

64. The Air Force Manual on International Law, at 6-3. Quoted in [2], p. 701.

65. U.S. ICJ Memorandum/GA App. at 31. Quoted at [2], p. 146.

66. ICJ Hearing, November 15, at 95-96. Quoted at [2], p. 147.

67. Advisory Opinion. [1], p. 31.

68. The Naval/Marine Commander's Handbook. at 8-5. Quoted in [2], p. 42.

69. The Naval/Marine Commander's Handbook. at 8-5. Quoted in [2], p. 42.

70. The Air Force Commander's Handbook. At 3-3. Quoted in [2], p. 43.

71. Quoted from [2], p. 367.

72. Cf. U.S. ICJ Memorial/GA App. at 21. Quoted in [2], p. 753.

73. ICJ Hearing, November 15, 1995, at 85. Quoted in [2], pp. 753-754.

74. Model Penal Code. Paragraph 2.02(c). Quoted in [2], p. 293-294.

75. United States Written Statement, p. 23. Quoted in Dissenting Opinion of Judge Weeramantry. [1], p. 12.

76. Cf. [2], p. 255.

77. Cf. [2], pp. 669-671.

78. Cf. [2], pp. 669-671.

79. Doctrine for Joint Theater Nuclear Operations, supra note 42, at I, 5-6. Quoted in [2], p. 672.

80. Joint Pub 3-12, Doctrine for Joint Nuclear Operations i. Quoted in [2], p. 734.

81. The Air Force Manual on International Law, at 6-7. Quoted in [2], p. 87.

82. The Air Force

83. Advisory Opinion. [1], p. 20.

84. Advisory Opinion. [1], p. 21.

85. Advisory Opinion. [1], p. 21.

86. U.S. ICJ Memorandum / GA App. 23-23. Quoted in [2], 708.

87. The Naval/Marine Commander's Handbook, supra note 28, at 10-2. Quoted in [2], p. 145.