THE LEGALITY OF THREAT OR USE
OF NUCLEAR WEAPONS
A GUIDE TO THE HISTORIC OPINION OF
THE INTERNATIONAL COURT OF JUSTICE
By John Burroughs
Foreword by Phon van den Biesen
INTERNATIONAL ASSOCIATION OF LAWYERS
AGAINST NUCLEAR ARMS
Lit Verlag, 1997
In an historic opinion issued 8 July 1996, the International Court of Justice (ICJ)
held that the threat or use of nuclear weapons is generally illegal, and that states are
obligated to bring to a conclusion negotiations on nuclear disarmament in all its aspects.
(1) Popularly known as the World Court, the ICJ is the judicial branch
of the United Nations, and the highest and most authoritative court in the world on
questions of international law. Its statement of the law governing nuclear weapons is
therefore of signal importance.
General illegality of the threat or use of nuclear weapons
In a formal conclusion, the Court held 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." (2) This conclusion is powerfully supported by key elements of the Court's
- Nuclear weapons have "unique characteristics," including "their
destructive capacity, their capacity to cause untold human suffering, and their ability to
cause damage to generations to come;" their "destructive power
contained in either space or time;" a nuclear explosion "releases not only
immense quantities of heat and energy, but also powerful and prolonged radiation,"
which "would affect health, agriculture, natural resources and demography over a very
wide area," and "has the potential to damage the future environment, food and
marine ecosystem, and to cause genetic defects and illness in future generations;" (3)
- 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
the use of such weapons in fact seems scarcely reconcilable with respect
for such requirements;" (4)
- Self-defense warrants "only measures which are proportional to the armed attack and
necessary to respond to it," and "a use of force that is proportionate under the
law of self-defence, must, in order to be lawful, also meet the requirements of the law
applicable in armed conflict which comprise in particular the principles and rules of
- The environment "represents the living space, the quality of life and the very
health of human beings, including generations unborn," and "States must take
environmental considerations into account when assessing what is necessary and
proportionate in the pursuit of legitimate military objectives" and in implementation
of the law applicable in armed conflict; (6)
- The nuclear weapon states failed to demonstrate that any use of nuclear weapons,
including a "clean" use involving "low yield" weapons, could comply
with legal requirements or avoid catastrophic escalation; (7)
- "[I]f the use of force itself in a given case is illegal - for whatever reason -
the threat to use such force will likewise be illegal." (8)
The force of the holding that threat or use is generally illegal is thus overwhelming
when viewed in the context of the entire opinion. It 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." (9) 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, threat or use in such a circumstance remains subject to the requirements of
humanitarian law. As the Court stated, a "fundamental" and
"intransgressible" rule is that "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."(10)
The strength of the general illegality conclusion is further revealed by the voting
pattern. Both that conclusion and the extreme circumstance/survival of the state provision
are set forth in paragraph 2E of the dispositif, which records the Court's formal
conclusions. The entire paragraph was voted for by seven of the fourteen judges then
serving on the Court, and was adopted as the Court's opinion based on the casting vote of
the President, Mohammed Bedjaoui. But, the judges' separate statements show that while the
extreme circumstance/survival of the state provision was intensely controversial, support
for general or categorical illegality was broad and deep. Three judges declined to vote
for paragraph 2E 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.
The obligation to eliminate nuclear weapons
In paragraph 2F of the dispositif, the Court unanimously held that "[t]here 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 Court explained that Article VI of the Nuclear Non-Proliferation Treaty
(NPT) imposes "an obligation to achieve a precise result - nuclear disarmament in all
its aspects - by adopting a particular course of conduct, namely, the pursuit of
negotiations on the matter in good faith." (11) The Court observed
that 182 states, "the vast majority of the international community," are parties
to the NPT, and that nuclear disarmament is "an objective of vital importance to the
whole of the international community today." (12)
Endorsed by every judge on the Court, this is now the authoritative interpretation of
Article VI of the NPT, and is perhaps the most important result of the case. Its
importance is underlined by the fact that it was not required by the request of the
General Assembly of the United Nations for clarification of the legal status of threat or
use of nuclear weapons, but rather was produced on the Court's own initiative. In the
Court's view, elimination of nuclear weapons is the only adequate response to the dilemmas
and risks posed by the nuclear age. Of special significance is the holding that Article VI
requires states to achieve nuclear disarmament through good faith negotiation. Talking is
not enough; the talk must lead to action. Also important is that the Court delinked the
obligation to achieve nuclear disarmament from the obligation, also found in Article VI,
to establish a treaty on general and complete disarmament. Nuclear weapon states can no
longer plausibly rely on the rationale that elimination of nuclear weapons must await
comprehensive global disarmament. Also significant is the implication that the obligation
applies to all states, not only those who are party to the NPT, thus binding such
threshold states as India, Israel, and Pakistan.
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, the ICJ has authoritatively
interpreted law which states acknowledge they must follow, including humanitarian law, the
United Nations Charter, and Article VI of the NPT. 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 NPT
review conferences, the General Assembly, national courts or parliaments, or the ICJ
itself - in which nuclear weapon policies are challenged.
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, its uncertainty with respect to an extreme circumstance of self-defence in
which the very survival of a state is at stake, and arms control and non-proliferation
measures such as United States-Russian bilateral reductions and the Comprehensive Test Ban
Most of the world disagrees. One hundred fifteen states voted for the December 1996
General Assembly resolution initiated by Malaysia calling for compliance with the opinion
by commencement in 1997 of negotiations leading towards a nuclear weapons convention. (14) To show that this is workable, the International Association of
Lawyers Against Nuclear Arms, its U.S. affiliate, the Lawyers' Committee on Nuclear
Policy, the International Network of Engineers and Scientists Against Proliferation, and
others have drafted a model nuclear weapons convention. Like the chemical and biological
weapons conventions already in force, the model convention sets forth an institutional
framework and measures accomplishing the total abolition of nuclear weapons. Numerous
states have also demanded nuclear disarmament in compliance with the opinion in
proceedings reviewing implementation of the NPT.
Other developments are also promising. Abolition 2000: A Global Network to Eliminate
Nuclear Weapons, was formed at the November 1995 hearings on the nuclear weapons case
before the ICJ in The Hague and now comprises more than 700 groups worldwide. The Network
has made conclusion of a nuclear weapons convention its central demand. The Canadian
Abolition 2000 Network, led by former Canadian Ambassador for Disarmament Douglas Roche,
conducted a series of town meetings discussing Canada's policy in light of the opinion.
The conclusions of the process, in particular that Canada should work for an end to NATO's
reliance on nuclear weapons, were presented at a parliamentary hearing. World Court
Project activists in the United Kingdom similarly have engaged policy-makers in dialogue
about the implications of the case, as have activists in other countries. Numerous cities
have passed resolutions calling for creation of a nuclear weapon free world in compliance
with the opinion. Non-violent direct action campaigns have demanded the withdrawal of
nuclear weapons from deployment based on the opinion, and it has been cited in defending
against prosecutions arising out of protest actions. (15)
As these initiatives reflect, contrary to the claims of the nuclear weapon states,
deterrence policies are highly vulnerable to challenge in light of the opinion. While the
Court declined to confront deterrence head on, it did hold 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 a committee 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. (16)
Moreover, the illegal threat of use is inherent in the postures of deterrence (hair
trigger deployment, declared policies of massive retaliation, first use, and 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. (17) Such postures are also inconsistent with implementation of
the obligation to eliminate nuclear arsenals through good faith negotiation.
The opinion therefore mandates 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. (18) 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 unanimously recognized that the only viable permanent response to the illegality
of threat or use is the achievement, in compliance with the NPT, of nuclear disarmament in
all its aspects.
1. Legality of the Threat or Use of Nuclear Weapons, General List No.
95 (Advisory Opinion of 8 July 1996). Unless otherwise stated, references are to this
opinion, which was requested by the General Assembly, not to the nuclear weapons advisory
opinion requested by the World Health Assembly.
2. Para. 105(2)E.
3. Paras. 35, 36.
4. Para. 95.
5. Paras. 41, 42.
6. Paras. 29, 30, 33.
7. Para. 94.
8. Para. 47.
9. Para. 105(2)E.
10. Paras. 78, 79 (emphasis added).
11. Para. 99.
12. Paras. 100, 103. Since the Court issued its opinion, the number
of states parties has risen to 186.
13. See Appendix B.
14. See Appendix E for the text of the resolution.
15. A case in Germany arising out of trespass on U.S. Army
headquarters in command of nuclear weapons in Europe illustrates how the opinion can
bolster the defence of protesters. While the decision acquitting the protesters has been
vacated on appeal and the case returned to the trial court for further proceedings, the
reasoning of the initial judge regarding the ICJ opinion is worth noting. He observed
regarding the Court's uncertainty as to an extreme circumstance of self-defence in which
the very survival of a state is at stake:
Because such an extreme situation no longer exists in any case since the end of the
East-West confrontation in Europe, the stationing of nuclear weapons and the maintenance
of installations necessary for their use is not (any longer) justifiable. The same is true
for the related military strategy which includes still the option of the first use of
nuclear weapons by U.S. Armed Forces as well as NATO.
Amtsgericht Stuttgart (District Court), Judge Wolf, B 8 Ds 1045/93, GJ 9 27928/93, B 8
(870) Cs 1039/96, B 8 Cs 1037/96, judgment dated 3 December 1996 (unofficial
The opinion has also been cited in defending protesters in the United Kingdom
(Reading), where an acquittal followed the prosecution's refusal to put on evidence;
Belgium, where a conviction was vacated based on lack of jurisdiction; in France, where a
conviction was vacated on the same ground; and in Wisconsin, Maine (the "Plowshares
8"), and Nevada in the United States. In Wisconsin, a partial acquittal was obtained;
defendants were convicted in other cases.
16. Committee on International Security and Arms Control, National
Academy of Sciences, The Future of U.S. Nuclear Weapons Policy (Washington, D.C.: National
Academy Press, 1997), p. 87 (emphasis supplied).
17. Richard Falk comments that the Court "explicitly avoids
making any legal assessment of deterrence in theory and practice. At the same time, the
decision does circumscribe the legal right to threaten or use nuclear weaponry in a manner
that seems inconsistent with the practice of deterrence in most of its forms, other than
possibly so-called minimum deterrence. A problematic character of the decision arises from
this failure to address more directly the current doctrines and practice of nuclear
weapons states, which leaves in doubt the policy implications of the advice being given.
Admittedly, the court was confronted by a dilemma: had it attempted to remove doubt as to
the legality of current practice by making detailed commentary on strategic doctrines in
various settings, it would have manifested a degree of technical incompetence that would
likely have considerably damaged its reputation as a responsible judicial body."
Falk, "Nuclear Weapons, International Law and the World Court: An Historic
Encounter," 91 American Journal of International Law (No. 1, January 1997), pp.
64-75, at pp. 70-71.
18. For the National Academy of Science recommendations, see The
Future of U.S. Nuclear Weapons Policy, op. cit., esp. at pp. 62-63. The Canberra
Commission on the Elimination of Nuclear Weapons was convened by the Australian government
and included a number of distinguished politicians, military officers, diplomats, and
others from around the world. Its report was released in 1996 and is available from the
government of Australia and on various web-sites, including