The Advisory Opinion of the International Court of Justice and the Statute of the International Criminal Court

John Burroughs

June 15, 1999

Paper presented at the conference on "Nuclear Policy and Security on the eve of the 21st century," St. Petersburg, Russia, June 18-20th, 1999

The International Court of Justice Advisory Opinion

Humanitarian law consists of rules and principles that regulate the conduct of warfare, seeking to strike a balance between the imperatives of war and the humanitarian impulse to moderate its savagery. Also known as the law of war or the law of armed conflict, it is codified in several important multilateral treaties, the Hague Conventions of 1907, the 1949 Geneva Conventions, the 1977 First Additional Protocol to the Geneva Conventions, and in other international instruments. Humanitarian law is widely acknowledged to be customary international law binding on states not parties to the relevant treaties. Customary international law is defined as based upon the general and consistent practice of states, followed out of a sense of legal obligation. Some customary rules also reflect underlying moral considerations.

The 1907 Hague Conventions represent the first systematic treaty codification of humanitarian rules. While the Hague Conventions did not adequately anticipate military techniques employed in the two world wars, notably "strategic" bombing of cities, they did express basic purposes of humanitarian law to set limits on warfare and protect non-combatant persons and property. Article 22 provided that "the right of belligerents to adopt means of injuring the enemy is not unlimited"; Article 23 prohibited the employment of poisoned weapons and weapons calculated to cause unnecessary suffering; Article 25 prohibited bombing of undefended cities; Article 27 enjoined protection "so far as possible" of buildings devoted to cultural and medical purposes.

The 1949 Geneva Conventions mainly aim at protecting prisoners of war, the wounded and sick, the shipwrecked, and civilians in occupied territories (e.g., after successful invasion of enemy territory).

The 1977 Protocol I to the Geneva Conventions comprehensively codifies humanitarian law in light of the terrible experiences of 20th century warfare, providing detailed and strict protection of civilians from the effects of warfare. It represents in good measure the world’s unambiguous repudiation of World War II strategic bombing. Unlike the older multilateral treaties, Protocol I has not yet been ratified by several declared or de facto nuclear weapon states, including the United States, France, India, Pakistan, and Israel, but most of its key provisions are acknowledged to state binding customary law.

From the outset of the project to seek an advisory opinion from the International Court of Justice, it was understood that the case for illegality would be based upon the essential incompatibility of nuclear weapons with humanitarian law. This was so because, due to the resistance of the nuclear weapon states, and unlike chemical and biological weapons, there is no express global prohibition of use of nuclear weapons. Thus humanitarian law was the centerpiece of most states' arguments, as well as the model briefs prepared by the International Association of Lawyers Against Nuclear Arms. As eminent international law scholar Professor George Abi-Saab argued for Egypt at the hearings in November 1995:

[T]he use of nuclear weapons is prohibited not because they are or they are called nuclear weapons. They fall under the prohibitions of the fundamental and mandatory rules of humanitarian law which long predate them, by their effects; not because they are nuclear weapons, but because they are indiscriminate weapons of mass destruction.

With the exception of France, which maintained a discreet silence on the subject, the nuclear weapon states participating in the hearings explicitly acknowledged the applicability of humanitarian law. Thus A.G. Khodakov, Director, Legal Department, Ministry of Foreign Affairs, Russian Federation, told the Court:

Restrictions set by the rules applicable to armed conflicts in respect of means and methods of warfare definitely also extend to nuclear weapons.

Similarly, for the United States, John McNeill, Senior Deputy General Counsel, Department of Defense, stated:

The United States has long shared the view that the law of armed conflict governs the use of nuclear weapons - just as it governs the use of conventional weapons.

The United Kingdom observed in its written statement:

Assuming that a State's use of nuclear weapons meets the requirements of self-defence, it must then be considered whether it conforms to the fundamental principles of the law of armed conflict regulating the conduct of hostilities.

But, Russia, the United States, and the United Kingdom maintained, whether a nuclear use complied with humanitarian law would depend upon the circumstances.

In its July 8, 1996 advisory opinion, the Court came down strongly on the side of the non-nuclear weapon states, concluding that threat or use of nuclear weapons is generrally illegal based in particular upon humanitarian law. The Court explained that under humanitarian law,

methods and means of warfare, which would preclude any distinction between civilian and military targets, or which would result in unnecessary suffering to combatants, are prohibited. In view of the unique characteristics of nuclear weapons, ... the use of such weapons in fact seems scarcely reconcilable with respect for such requirements.

Further, the Court found, the nuclear weapon states had failed to demonstrate that any use of nuclear weapons, including postulated use of "clean", low yield weapons, could comply with legal requirements or avoid catastrophic escalation.

The Court noted that the humanitarian rules forbidding the infliction of unnecessary suffering and indiscriminate harm are supported by the Martens Clause, proposed by Russian foreign minister Feodoro de Martens in 1899, and set forth in the Hague Conventions and in the Geneva Conventions and Protocols. As stated in the 1977 Geneva Protocol I, the Clause provides:

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 principles of humanity and from the dictates of the public conscience. (Emphasis added.)

The Court also stated that these "fundamental" rules are supported by "elementary considerations of humanity" and are to be observed by all states whether or not they have ratified the relevant treaties because they are "intransgressible principles of international customary law".

Humanitarian law, the Court further explained, applies in situations of self-defense and threat. "[A] use of force that is proportionate under the law of self-defence," the Court stated, "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". And, "[i]f an envisaged use of force would not meet the requirements of humanitarian law, a threat to engage in such use would also be contrary to that law".

When combined with the Court's other holdings regarding environmental law and the law of neutrality, the Court's analysis of humanitarian law gave great force to its conclusion that threat or use of nuclear weapons is generally illegal. That conclusion was qualified by the statement that "the Court cannot conclude definitely 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 explanation, the Court referred to the right of self-defence, the policy of deterrence, whose legality the Court declined directly to assess, and the elements of fact and law at its disposal. However, the judges’ separate statements show that the extreme circumstance/survival of the state provision was intensely controversial, with only a few judges affirmatively supporting the formulation. In contrast, support for general or categorical illegality was broad and deep. The majority was formed by seven of the fourteen judges, with the deciding vote cast by President Modhammed Bedjaoui. Three judges declined to join the majority because it did not definitively hold threat or use of nuclear weapons to be categorically illegal, that is, illegal in every circumstance. Thus ten judges supported at least a holding of general illegality.

Further, as President Bedjaoui observed, the extreme circumstance provision is only a statement of uncertainty in light of the legal and factual material available to the Court. He stated: "I cannot sufficiently emphasize the fact that the Court’s inability to go beyond this statement of the situation can in no manner be interpreted to mean that it is leaving the door ajar to recognition of the legality of the threat or use of nuclear weapons." Nowhere in the opinion did the Court identify any legal threat or use of nuclear weapons. Further, uncertainty could arise only when 1) a state is acting in self-defence; 2) an extreme circumstance exists; and 3) the extreme circumstance threatens the very survival of the defending state. The indivisibility of threat and use meant that the Court was considering whether a nuclear threat is forbidden as a means of seeking to ensure the survival of a state faced with an actual or imminent attack by nuclear weapons or similarly catastrophic means. In the only instances of use of nuclear weapons in time of war, the United States’ atomic bombings of Hiroshima and Nagasaki, the survival of the United States was not threatened in any way. Those bombings were unquestionably illegal because they violated the prohibitions of attacking civilians and inflicting indiscriminate harm which the Court expressly held existed prior to the commencement of the nuclear age.

If an extreme circumstance implicating the very survival of the defending state does arise, the threat or use of nuclear weapons remains subject to the "fundamental" and "intransgressible" requirements of humanitarian law. In particular, the following categorical and unambiguous rule applies: "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." The severely restrictive consequences of this fundamental constraint for the threat or use of nuclear weapons imply that even when the survival of a state acting in self-defence is at stake, uncertainty would arise with respect only to limited threats or uses like the postulated "clean" use of "low yield" nuclear weapons which the Court found the nuclear weapon states had not demonstrated to be legal but also did not expressly find to be illegal.

The applicability of humanitarian and other law to an extreme circumstance of self-defence involving the very survival of a state is also recognized by paragraph 2C of the dispositif, which provides that "[a] threat or use of force by means of nuclear weapons … that fails to meet all the requirements of Article 51 is unlawful." Thus any threat or use must meet the requirements for the lawful exercise of self-defence, necessity and proportionality, which in turn require protection of the environment and compliance with humanitarian law. A formal conclusion also provides that "[a] threat or use of nuclear weapons should also be compatible with … international law applicable in armed conflict, particularly … humanitarian law." In separate statements, a large majority of the judges confirmed that humanitarian and other law applies in an extreme circumstance of self-defence involving the very survival of a state.

Thus having found that the nuclear weapon states had failed to demonstrate to its satisfaction the legality of any use of nuclear weapons, the Court placed an impossible burden of proof on those states to ever succeed in doing so: There must exist "an extreme circumstance of self-defence, in which the very survival of a state would be at stake," and the threat or use of nuclear weapons in that circumstance must comply with law protecting civilians, combatants, neutral states, and the environment from indiscriminate, unnecessary, and disproportionate effects of warfare.

This analysis can be illustrated by reference to the standard, but by no means the only, scenario in which nuclear weapon states justify nuclear threats and possibly even uses: threatened second use in response to another state's first use. Noting that "[c]ertain States asserted that the use of nuclear weapons in the conduct of reprisals would be lawful," the Court stated that it does not "have to pronounce on the question of belligerent reprisals [i.e., reprisals in time of war] save to observe that in any case any right of recourse to such reprisals would, like self-defence, be governed inter alia by the principle of proportionality".

A US State Department lawyer has contended that the Court’s refusal directly to address the legality of nuclear reprisals leaves retaliatory deterrence unchallenged. However, this view overlooks the Court’s holding that the risk of escalation and environmental considerations must be taken into account in assessing proportionality. More fundamentally, it ignores the Court’s holdings that humanitarian law protecting civilians must be obeyed in all circumstances and that the requirement of proportionality incorporates humanitarian law.

A reprisal has classically been defined as an otherwise illegal act, taken in response to an enemy’s prior illegal act, executed with the intent of causing the enemy to cease such acts. Protocol I to the Geneva Conventions includes comprehensive prohibitions on reprisals against civilians and objects indispensable to the survival of civilians (e.g., crops, water installations) as well as the environment. As with the Protocol I rules forbidding the infliction of severe environmental damage, the nuclear weapon states had argued that the use of nuclear weapons is not governed by these provisions, which they characterized as "new" law. The Court did not specifically address this contention, but its rejection is inherent in its analysis of humanitarian law.

The Court described humanitarian prohibitions of attacking civilians and inflicting indiscriminate harm and unnecessary suffering as pre-dating the invention of nuclear weapons, and as applying "to all kinds of weapons, those of the past, those of the present and those of the future." As noted above, the Court stated that those rules are "fundamental" and "intransgressible", and, it bears repeating, formulated the following "cardinal" principle of humanitarian law in a way further clarifying that it applies in all circumstances: 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." The categorical nature of the prohibition protecting civilians was recently confirmed by the International Criminal Tribunal for the Former Yugoslavia, in Prosecutor v. Martic (Rule 61), Case IT-95-11-R61 (8 March 1996), paras. 15-17. Applying humanitarian law including Article I common to all Geneva Conventions, the Tribunal stated: "no circumstances would legitimize an attack against civilians even if it were a response proportionate to a similar violation perpetrated by the other party". It follows from the ICJ opinion, the Martic case, and other authorities that nuclear reprisals are forbidden, beginning but not ending with the reprisals contemplated by the strategy of massive retaliation that target or indiscriminately kill and injure civilian populations on a vast scale.

The Court’s holdings came in response to a request for an advisory opinion by the General Assembly, not in the context of a contentious case that concerns a specific dispute among states. Because it is advisory, the opinion as such is not directly binding on the United Nations or its member states. However, as Judge Shahabuddeen has observed, "… although an advisory opinion has no binding force under article 59 of the Statute, it is as authoritative a statement of the law as a judgment rendered in contentious proceedings." The United States recently acknowledged the authority of advisory opinions in the case brought by the Federal Republic of Yugoslavia challenging the NATO bombing, referring to the Court's advisory opinion in the case on reservations to Genocide as an "important Opinion that is the cornerstone of the modern law of reservations". Thus in the nuclear weapons case, the ICJ has authoritatively interpreted law which states acknowledge they must follow, including humanitarian law and the United Nations Charter. Accordingly, the opinion is binding in the sense that states must comply with the law it applies. It can be cited as an authoritative statement of the law in any political or legal setting – including in national decision-making bodies responsible for nuclear policy, national courts and parliaments, and international settings like NPT review conferences and the UN General Assembly, or the ICJ itself.

While noting the opinion’s advisory character, the nuclear weapon states have not sought to deny its authority. Rather they have claimed that their policies comply with the law as stated in the opinion, referring to the Court’s refusal directly to pass upon deterrence and its uncertainty with respect to an extreme circumstance of self-defence in which the very survival of a state is at stake. It is true that the Court declined to confront deterrence head on. Nonetheless, deterrence policies are highly vulnerable to challenge in light of the opinion. While not expressly evaluating deterrence, the Court did hold that that a threat of use of illegal force is itself illegal. In realistic scenarios, no type of nuclear weapon now deployed can be used or threatened to be used in compliance with humanitarian and other applicable law. As the Committee on International Security and Arms Control of the U.S. National Academy of Sciences stated:

[T]he ICJ unanimously agreed that the threat or use of nuclear weapons is strictly limited by generally accepted laws and humanitarian principles that restrict the use of force. Accordingly, any threat or use of nuclear weapons must be limited to, and necessary for, self defense; it must not be targeted at civilians, and be capable of distinguishing between civilian and military targets; and it must not cause unnecessary suffering to combatants, or harm greater than that unavoidable to achieve military objectives. In the committee’s view, the inherent destructiveness of nuclear weapons, combined with the unavoidable risk that even the most restricted use of such weapons would escalate to broader attacks, makes it extremely unlikely that any contemplated threat or use of nuclear weapons would meet these criteria.

Moreover, the illegal threat of use is inherent in the postures of deterrence (hair trigger deployment, declared policies of massive retaliation, first use, defence of "vital interests," etc.) now continuously maintained by the nuclear weapon states absent any extreme circumstance of self-defence in which their very survival is at stake.

The opinion therefore supports the immediate implementation of measures to reduce the level of threat and risk in existing nuclear postures like those recommended by the U.S. National Academy of Sciences and the Canberra Commission on the Elimination of Nuclear Weapons. These include adoption of unconditional no first use commitments, taking nuclear forces off alert, and separation of warheads from delivery systems. And, consistent with the calls for the abolition of nuclear weapons now being made by these and other authorities, most states, and citizens’ groups around the world, the Court recognized that the only viable permanent response to the illegality of threat or use is the achievement, in compliance with the Nuclear Non-Proliferation Treaty, of complete nuclear disarmament. The Court unanimously held: "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."

The Statute of the International Criminal Court:

The most recent statement of humanitarian law is found in the Statute of the International Criminal Court, adopted in Rome on July 17, 1998. The Statute defines the offenses of genocide, crimes against humanity, and war crimes under which individuals would be prosecuted once that court is in operation. Its substantive provisions were explicitly negotiated on the basis that they would reflect the present state of law binding on all states. While the Statute is not yet in effect, as the required number of states (60) has not yet ratified the instrument, the Statute nonetheless stands as a consensus-based statement of presently binding law defining war crimes.

The Statute of the International Criminal Court includes the following "serious violations of the laws and customs applicable in international armed conflict, within the established framework of international law" (Art. 8(b)):

"Intentionally directing attacks against the civilian population as such or against individual civilians not taking direct part in hostilities" (Art. 8(b)(i));

"Intentionally directing attacks against civilian objects, that is, objects which are not military objectives" (Art. 8(b)(ii));

"Intentionally launching an attack in the knowledge that such attack will cause incidental loss of life or injury to civilians or damage to civilian objects or widespread, long-term and severe damage to the natural environment which would be clearly excessive in relation to the concrete and direct overall military advantage anticipated" (Art. 5(b)(iv)).

Other provisions of the Statute are relevant as well, for example the prohibition on "wilful killing" (Art. 8(2)(a)(i)), drawn from the Geneva Conventions, and the prohibition as a crime against humanity of "inhumane acts ... intentionally causing great suffering" directed against civilian populations (Art. 7(1)(k).

The Statute thus clearly states the principle of civilian immunity also relied upon by the International Court of Justice. The Statute also sets forth a principle of proportionality governing the extent of permissible damage to civilian society and the environment arising from attacks on military objectives, a principle not relied upon by the Court. At first glance, it would seem that this principle would effectively prohibit the use of nuclear weapons. However, caution must be exercised here, because there is a significant elasticity contained in the principle including in the words "clearly excessive" and "overall military advantage anticipated". For example, many would contend that the NATO bombing of Yugoslavia was disproportionate to the achievement of military objectives, since it seemed not directly to support the achievement of military operations - for example, a NATO ground invasion of Kosovo - but rather simply to punish Yugoslav society until its government was ready to accomodate NATO demands. NATO, however, presumably would argue that an "overall" military advantage was gained through the weakening of the infrastructure supporting Yugoslav armed forces. Nonetheless, given the extraordinary nature of nuclear weapons, including a feature whose uncontrollable and indiscriminate effects in space and time cannot be avoided, namely the release of radioactivity, it remains the case that the proportionality requirement supports their inherent illegality.

The route chosen by the ICJ to support the general illegality of threat or use of nuclear weapons was simpler than reliance on the principle of proportionality. The ICJ emphasized the rules prohibiting the infliction of unnecessary suffering and the use of a weapon incapable of distinguishing between civilian and military targets - in other words, an inherently indiscriminate weapon. These rules also make their appearance in the Statute of the International Criminal Court, albeit in a rather indirect way: they serve as criteria for the addition of weapons to a list of prohibited weapons. It is worth explaining the background of this provision, because it illustrates the present political and legal dilemma posed by the resistance of the world's most powerful states to the creation of an express global ban on nuclear explosive devices.

The first prohibited weapons option in the draft Statute coming into the negotiations that commenced June 15, 1998 explicitly named only "asphyxiating, poisonous or other gases, and all analogous liquids, materials, or devices", poison weapons, chemical and biological weapons, and expanding bullets as weapons whose use would constitute a war crime. A group of NGOs concerned with prohibited weapons, known as the Peace Caucus, advocated for the express identification as well of nuclear weapons, landmines, and blinding laser weapons. As a fallback, the Caucus supported a general provision criminalizing the use of weapons which cause unnecessary suffering or which are inherently indiscriminate. As a last resort fallback, the Caucus supported provisions making clear that the list of prohibited weapons was incomplete, for example by placing the list in an annex subject to expansion in the future.

The position of a majority of states was similar to that of the Peace Caucus. These states supported options that either expressly identified nuclear weapons (some states also referred to landmines) or contained a general provision regarding weapons that cause unnecessary suffering or indiscriminate damage that would implicitly cover nuclear weapons. The Non-Aligned Movement, in its Cartagena meeting a month before, had made inclusion in the Statute of use of nuclear weapons as a crimes a key objective. Of course, the nuclear weapon states absolutely refused a Statute that would expressly criminalize use of nuclear weapons.

Some 60 European, African, Latin American and Asian states, along with Canada, formed an alliance known as the "like-minded states" which was the engine for the process of creating the Statute. Since in the interest of having a workable institution the like-minded states wanted the nuclear weapon states to ratify the Statute or at least accept and tolerate it even if not parties, there was an impasse regarding nuclear weapons. Reportedly at the instance of some Arab states, who were especially offended by the omission of nuclear weapons while chemical and biological weapons were criminalized, the impasse was resolved in the very last days of the negotiations, without public debate, by deleting the express reference to chemical and biological weapons, retaining the prohibitions of employment of expanding bullets, poison weapons, and poisonous gases and analogous materials, and providing that other weapons which are inherently indiscriminate or of a nature to cause unnecessary suffering and which are the subject of a comprehensive prohibition can be included in an annex in the future pursuant to the amendment process.

The deletion of express reference to chemical and biological weapons is not as egregious as might appear at first glance, because the provision regarding poisonous gas and analogous materials covers chemical weapons and possibly biological weapons. The provision is drawn from the Geneva Gas Protocol of 1925, which has been understood since then to apply to all chemical weapons. Further, the Gas Protocol expressly extended the commitment to "bacteriological" weapons, so arguably the provision in the ICC Statute, while not mentioning bacteriological or biological weapons, should be so interpreted as well. While not encompassed by the prohibited weapons provisions, the employment of nuclear weapons as well as landmines and other indiscriminate weapons is generally covered by other provisions defining war crimes and crimes against humanity, as explained above. Further, the identification of the review and amendment process as a means to add weapons in the future, and the statement of criteria for so doing (inherently indiscriminate or of a nature to cause unnecessary suffering), is symbolically and perhaps politically and procedurally useful. It effectively condemns nuclear weapons, landmines, blinding laser weapons, and other weapons that are indiscriminate or cause unnecessary suffering and points towards their explicit listing at a later point. However, the requirement that a "comprehensive prohibition" exist before a weapon is added is a major potential hurdle, depending on how states interpret the term, and the amendment process itself is daunting since it requires ratification by seven-eighths of states parties.

The Statute of the International Criminal Court bears on the problem of nuclear weapons in several ways. It strengthens humanitarian law by confirming and elaborating many of its central principles, including civilian immunity and and a related principle of proportionality. It implicitly acknowledges that there are weapons like nuclear weapons and landmines that deserve to be expressly prohibited because they cause unnecessary suffering and are inherently indiscriminate. Most importantly, perhaps, if the International Criminal Court can became an effective global institution, nuclear weapons will be increasingly out of place. How can the threat of mass atrocities through use of nuclear weapons be justified as a world consensus grows that gross violations of human rights are unacceptable and their perpetrators subject to prosecution and punishment? Thus the Statute supports the advisory opinion of the International Court of Justice, by highlighting the importance of compliance with humanitarian law, and pointing towards a world in which the threat of mass destruction will be unthinkable.