INTERNATIONAL COURT OF JUSTICE

REPORTS OF JUDGMENTS,
ADVISORY OPINIONS AND ORDERS

LEGALITY OF THE THREAT OR USE
OF NUCLEAR WEAPONS

ADVISORY OPINION OF 8 JULY 1996

1996

COUR INTERNATIONALE DE JUSTICE

RECUEIL DES ARRETS,
AVIS CONSULTATIFS ET ORDONNANCES

LICEITE DE LA MENACE OU DE L’EMPLOI
D’ARMES NUCLEAIRES

AVIS CONSULTATIF DU 8 JUILLET 1996
Official citation:

Legality of the Threat or Use of Nuclear Weapons,
Advisory Opinion, I.C.J. Reports 1996, p. 226

Mode officiel de citation:

Licéité de la menace ou de l'emploi d'armes nucléaires,
avis consultatif, CILJ. Recueil 1996, p. 226

Sales number
ISSN 0074-4441 N° de vente: 679

ISBN 92-1-070743-5

1996
8 July
General List
No. 95

226

INTERNATIONAL COURT OF JUSTICE
YEAR 1996

8 July 1996

LEGALITY OF THE THREAT OR USE
OF NUCLEAR WEAPONS

Jurisdiction of the Court to give the advisory opinion requested — Article 65,
paragraph 1, of the Statute — Body authorized to request an opinion
Article 96, paragraphs I and 2, of the Charter — Activities of the General
Assembly — “Legal question” Political aspects of the question posed —
Motives said to have inspired the request and political implications that the
opinion might have.

Discretion of the Court as to whether or not it will give an opinion —
Article 65, paragraph 1, of the Statute —- Compelling reasons — Vague and
abstract question — Purposes for which the opinion is sought — Possible effects
of the opinion on current negotiations — Duty of the Court not to legislate.

Formulation of the question posed — English and French texts — Clear
objective — Burden of proof.

Applicable law — International Covenant on Civil and Political Rights —
Arbitrary deprivation of life — Convention on the Prevention and Punishment
of the Crime of Genocide — Intent against a group as such — Existing norms
relating to the safeguarding and protection of the environment — Environmen-
tal considerations as an element to be taken into account in the implementation
of the law applicable in armed conflict — Application of most directly relevant
law: law of the Charter and law applicable in armed conflict.

Unique characteristics of nuclear weapons.

Provisions of the Charter relating to the threat or use of force — Article 2,
paragraph 4 — The Charter neither expressly prohibits, nor permits, the use of
any specific weapon — Article 51 — Conditions of necessity and proportionality
— The notions of “threat” and “use” of force stand together — Possession of
nuclear weapons, deterrence and threat.

Specific rules regulating the lawfulness or unlawfulness of the recourse to
nuclear weapons as such — Absence of specific prescription authorizing the
threat or use of nuclear weapons — Unlawfulness per se: treaty law — Instru-
ments prohibiting the use of poisoned weapons — Instruments expressly pro-
hibiting the use of certain weapons of mass destruction — Treaties concluded
in order to limit the acquisition, manufacture and possession of nuclear weapons,
the deployment and testing of nuclear weapons — Treaty of Tlatelolco
Treaty of Rarotonga — Declarations made by nuclear-weapon States on the

4
227 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

occasion of the extension of the Non-Proliferation Treaty — Absence of compre-
hensive and universal conventional prohibition of the use or the threat of use of
nuclear weapons as such — Unlawfulness per se: customary law — Consistent
practice of non-utilization of nuclear weapons — Policy of deterrence — Gen-
eral Assembly resolutions affirming the illegality of nuclear weapons — Con-
tinuing tensions between the nascent opinio juris and the still strong adherence
to the practice of deterrence.

Principles and rules of international humanitarian law — Prohibition of
methods and means of warfare precluding any distinction between civilian and
military targets or resulting in unnecessary suffering to combatants — Martens
Clause — Principle of neutrality — Applicability of these principles and rules to
nuclear weapons — Conclusions.

Right of a State to survival and right to resort to self-defence — Policy of
deterrence — Reservations to undertakings given by certain nuclear-weapon
States not to resort to such weapons.

Current state of international law and elements of fact available to the Court
— Use of nuclear weapons in an extreme circumstance of self-defence in which
the very survival of a State is at stake.

Article VI of the Non-Proliferation Treaty — Obligation to negotiate in good
faith and to achieve nuclear disarmament in all its aspects.

ADVISORY OPINION

Present: President Bepsaout; Vice-President SCHWEBEL; Judges Oba,
GUILLAUME, SHAHABUDDEEN, WEERAMANTRY, RANJEVA, HERCZEGH,
Sui, FLEISCHHAUER, KOROMA, VERESHCHETIN, FERRARI BRAVO,
Hicons; Registrar VALENCIA-OspINA.

On the legality of the threat or use of nuclear weapons,

Tue Court,

composed as above,

gives the following Advisory Opinion:

1. The question upon which the advisory opinion of the Court has been
requested is set forth in resolution 49/75 K adopted by the General Assembly of
the United Nations (hereinafter called the “General Assembly”) on 15 Decem-
ber 1994. By a letter dated 19 December 1994, received in the Registry by
facsimile on 20 December 1994 and filed in the original on 6 January 1995,
the Secretary-General of the United Nations officially communicated to the
Registrar the decision taken by the General Assembly to submit the question

to the Court for an advisory opinion. Resolution 49/75 K, the English text of
which was enclosed with the letter, reads as follows:

“The General Assembly,

Conscious that the continuing existence and development of nuclear
weapons pose serious risks to humanity,

Mindful that States have an obligation under the Charter of the United
228

THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

Nations to refrain from the threat or use of force against the territorial
integrity or political independence of any State,

Recalling its resolutions 1653 (XVI) of 24 November 1961, 33/71 B of
14 December 1978, 34/83 G of 11 December 1979, 35/152 D of 12 Decem-
ber 1980, 36/921 of 9 December 1981, 45/59B of 4 December 1990 and
46/37 D of 6 December 1991, in which it declared that the use of nuclear
weapons would be a violation of the Charter and a crime against
humanity,

Welcoming the progress made on the prohibition and elimination of
weapons of mass destruction, including the Convention on the Prohibition
of the Development, Production and Stockpiling of Bacteriological (Bio-
logical) and Toxin Weapons and on Their Destruction! and the Conven-
tion on the Prohibition of the Development, Production, Stockpiling and
Use of Chemical Weapons and on Their Destruction’,

Convinced that the complete elimination of nuclear weapons is the only
guarantee against the threat of nuclear war,

Noting the concerns expressed in the Fourth Review Conference of the
Parties to the Treaty on the Non-Proliferation of Nuclear Weapons that
insufficient progress had been made towards the complete elimination of
nuclear weapons at the earliest possible time,

Recalling that, convinced of the need to strengthen the rule of law in
international relations, it has declared the period 1990-1999 the United
Nations Decade of International Law,

Noting that Article 96, paragraph 1, of the Charter empowers the
General Assembly to request the International Court of Justice to give an
advisory opinion on any legal question,

Recalling the recommendation of the Secretary-General, made in his
report entitled ‘An Agenda for Peace’*, that United Nations organs that
are authorized to take advantage of the advisory competence of the Inter-
national Court of Justice turn to the Court more frequently for such
opinions,

Welcoming resolution 46/40 of 14 May 1993 of the Assembly of the
World Health Organization, in which the organization requested the Inter-
national Court of Justice to give an advisory opinion on whether the use of
nuclear weapons by a State in war or other armed conflict would be a
breach of its obligations under international law, including the Constitu-
tion of the World Health Organization,

Decides, pursuant to Article 96, paragraph 1, of the Charter of the
United Nations, to request the International Court of Justice urgently to
render its advisory opinion on the following question: ‘Is the threat or use
of nuclear weapons in any circumstance permitted under international
law?

! Resolution 2826 (XXVI), annex.

2 See Official Records of the General Assembly, Forty-seventh Session, Supple-
ment No. 27 (A/47/27), appendix I.

3 Resolution 44/23.

4 A/47/277-S/24111.”
229 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

2. Pursuant to Article 65, paragraph 2, of the Statute, the Secretary-General
of the United Nations communicated to the Court a dossier of documents
likely to throw light upon the question.

3. By letters dated 21 December 1994, the Registrar, pursuant to Article 66,
paragraph 1, of the Statute, gave notice of the request for an advisory opinion
to all States entitled to appear before the Court.

4. By an Order dated 1 February 1995 the Court decided that the States
entitled to appear before it and the United Nations were likely to be able to fur-
nish information on the question, in accordance with Article 66, paragraph 2, of
the Statute. By the same Order, the Court fixed, respectively, 20 June 1995 as
the time-limit within which written statements might be submitted to it on the
question, and 20 September 1995 as the time-limit within which States and
organizations having presented written statements might submit written com-
ments on the other written statements in accordance with Article 66, para-
graph 4, of the Statute. In the aforesaid Order, it was stated in particular that
the General Assembly had requested that the advisory opinion of the Court be
rendered “urgently”; reference was also made to the procedural time-limits
already fixed for the request for an advisory opinion previously submitted to
the Court by the World Health Organization on the question of the Legality of
the Use by a State of Nuclear Weapons in Armed Conflict.

On 8 February 1995, the Registrar addressed to the States entitled to appear
before the Court and to the United Nations the special and direct communica-
tion provided for in Article 66, paragraph 2, of the Statute.

5. Written statements were filed by the following States: Bosnia and Herze-
govina, Burundi, Democratic People’s Republic of Korea, Ecuador, Egypt,
Finland, France, Germany, India, Ireland, Islamic Republic of Iran, Italy,
Japan, Lesotho, Malaysia, Marshali Islands, Mexico, Nauru, Netherlands,
New Zealand, Qatar, Russian Federation, Samoa, San Marino, Solomon
Islands, Sweden, United Kingdom of Great Britain and Northern Ireland, and
United States of America. In addition, written comments on those written
statements were submitted by the following States: Egypt, Nauru and Solomon
Islands. Upon receipt of those statements and comments, the Registrar com-
municated the text to all States having taken part in the written proceedings.

6. The Court decided to hold public sittings, opening on 30 October 1995, at
which oral statements might be submitted to the Court by any State or organi-
zation which had been considered likely to be able to furnish information on
the question before the Court. By letters dated 23 June 1995, the Registrar
requested the States entitled to appear before the Court and the United
Nations to inform him whether they intended to take part in the oral proceed-
ings; it was indicated, in those letters, that the Court had decided to hear,
during the same public sittings, oral statements relating to the request for an
advisory opinion from the General Assembly as well as oral statements con-
cerning the above-mentioned request for an advisory opinion laid before the
Court by the World Health Organization, on the understanding that the United
Nations would be entitled to speak only in regard to the request submitted by
the General Assembly, and it was further specified therein that the participants
in the oral proceedings which had not taken part in the written proceedings
would receive the text of the statements and comments produced in the course
of the latter.

7. By a letter dated 20 October 1995, the Republic of Nauru requested the
Court’s permission to withdraw the written comments submitted on its behalf

7
230 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

in a document entitled “Response to submissions of other States”. The Court
granted the request and, by letters dated 30 October 1995, the Deputy-Regis-
trar notified the States to which the document had been communicated, speci-
fying that the document consequently did not form part of the record before

the Court.

8. Pursuant to Article 106 of the Rules of Court, the Court decided to make
the written statements and comments submitted to the Court accessible to the
public, with effect from the opening of the oral proceedings.

9. In the course of public sittings held from 30 October 1995 to 15 Novem-
ber 1995, the Court heard oral statements in the following order by:

for the Commonwealth
of Australia:

for the Arab Republic
of Egypt:

for the French Republic:

for the Federal Republic
of Germany :

for Indonesia:

for Mexico:

for the Islamic
Republic of Iran:

for Italy:

for Japan:

Mr. Gavan Griffith, Q.C., Solicitor-General of
Australia, Counsel,

The Honourable Gareth Evans, Q.C., Senator,
Minister for Foreign Affairs, Counsel;

Mr. George Abi-Saab, Professor of International
Law, Graduate Institute of International Stud-
ies, Geneva, Member of the Institute of Interna-
tional Law;

Mr. Marc Perrin de Brichambaut, Director of Legal
Affairs, Ministry of Foreign Affairs,

Mr. Alain Pellet, Professor of International Law,
University of Paris X and Institute of Political
Studies, Paris;

Mr. Hartmut Hillgenberg, Director-General of
Legal Affairs, Ministry of Foreign Affairs;

H.E. Mr. Johannes Berchmans Soedarmanto
Kadarisman, Ambassador of Indonesia to the
Netherlands;

HE. Mr. Sergio Gonzalez Galvez, Ambassador,
Under-Secretary of Foreign Relations;

HE. Mr. Mohammad J. Zarif, Deputy Minister,
Legal and International Affairs, Ministry of
Foreign Affairs;

Mr. Umberto Leanza, Professor of International
Law at the Faculty of Law at the University of
Rome “Tor Vergata”, Head of the Diplomatic
Legal Service at the Ministry of Foreign Affairs;

H.E. Mr. Takekazu Kawamura, Ambassador,
Director General for Arms Control and Scien-
tific Affairs, Ministry of Foreign Affairs,

Mr. Takashi Hiraoka, Mayor of Hiroshima,
Mr. Iccho Itoh, Mayor of Nagasaki;
231 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

for Malaysia:

for New Zealand:

for the Philippines:

for Qatar:

for the Russian
Federation:

for San Marino:

for Samoa:

for the Marshall Islands :

for Solomon Islands:

H.E. Mr. Tan Sri Razali Ismail, Ambassador, Per-
manent Representative of Malaysia to the United
Nations,

Dato’ Mohtar Abdullah, Attorney-General;

The Honourable Paul East, Q.C., Attorney-General
of New Zealand,

Mr. Allan Bracegirdle, Deputy Director of Legal
Division of the New Zealand Ministry for For-
eign Affairs and Trade;

H.E. Mr. Rodolfo S. Sanchez, Ambassador of the
Philippines to the Netherlands,

Professor Merlin N. Magallona, Dean, College of
Law, University of the Philippines;

H.E. Mr. Najeeb ibn Mohammed Al-Nauimi,
Minister of Justice;

Mr. A. G. Khodakov, Director, Legal Department,
Ministry of Foreign Affairs;

Mrs. Federica Bigi, Embassy Counsellor, Official
in Charge of Political Directorate, Department
of Foreign Affairs;

H.E. Mr. Neroni Slade, Ambassador and Perma-
nent Representative of Samoa to the United
Nations,

Miss Laurence Boisson de Chazournes, Assistant
Professor, Graduate Institute of International
Studies, Geneva,

Mr. Roger S. Clark, Distinguished Professor of Law,
Rutgers University School of Law, Camden, New
Jersey;

The Honourable Theodore G. Kronmiller, Legal
Counsel, Embassy of the Marshall Islands to the
United States of America,

Mrs. Lijon Eknilang, Council Member, Rongelap
Atoll Local Government;

The Honourable Victor Ngele, Minister of Police
and National Security,

Mr. Jean Salmon, Professor of Law, Université
libre de Bruxelles,

Mr. Eric David, Professor of Law, Université libre
de Bruxelles,

Mr. Philippe Sands, Lecturer in Law, School of
Oriental and African Studies, London Univer-
sity, and Legal Director, Foundation for Inter-
national Environmental Law and Development,

Mr. James Crawford, Whewell Professor of Inter-
national Law, University of Cambridge;
232 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

for Costa Rica: Mr. Carlos Vargas-Pizarro, Legal Counsel and
Special Envoy of the Government of Costa Rica;

for the United Kingdom
of Great Britain and The Rt. Honourable Sir Nicholas Lyell, Q.C., M.P.,

Northern Ireland: Her Majesty’s Attorney-General;
for the United States Mr. Conrad K. Harper, Legal Adviser, United
of America: States Department of State,

Mr. Michael J. Matheson, Principal Deputy Legal
Adviser, United States Department of State,
Mr. John H. McNeill, Senior Deputy General
Counsel, United States Department of Defense;
for Zimbabwe: Mr. Jonathan Wutawunashe, Chargé d’affaires a.1.,
Embassy of the Republic of Zimbabwe in the
Netherlands.

Questions were put by Members of the Court to particular participants in the
oral proceedings, who replied in writing, as requested, within the prescribed
time-limits; the Court having decided that the other participants could also
reply to those questions on the same terms, several of them did so. Other ques-
tions put by Members of the Court were addressed, more generally, to any par-
ticipant in the oral proceedings; several of them replied in writing, as requested,
within the prescribed time-limits.

10. The Court must first consider whether it has the jurisdiction to
give a reply to the request of the General Assembly for an advisory
opinion and whether, should the answer be in the affirmative, there is any
reason it should decline to exercise any such jurisdiction.

The Court draws its competence in respect of advisory opinions from
Article 65, paragraph 1, of its Statute. Under this Article, the Court

“may give an advisory opinion on any legal question at the request
of whatever body may be authorized by or in accordance with the
Charter of the United Nations to make such a request”.

11. For the Court to be competent to give an advisory opinion, it is
thus necessary at the outset for the body requesting the opinion to be
“authorized by or in accordance with the Charter of the United Nations
to make such a request”. The Charter provides in Article 96, para-
graph 1, that: “The General Assembly or the Security Council may
request the International Court of Justice to give an advisory opinion on
any legal question.”

Some States which oppose the giving of an opinion by the Court
argued that the General Assembly and Security Council are not entitled

10
233 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

to ask for opinions on matters totally unrelated to their work. They
suggested that, as in the case of organs and agencies acting under
Article 96, paragraph 2, of the Charter, and notwithstanding the difference
in wording between that provision and paragraph 1 of the same Article,
the General Assembly and Security Council may ask for an advisory
opinion on a legal question only within the scope of their activities.

In the view of the Court, it matters little whether this interpretation of
Article 96, paragraph 1, is or is not correct; in the present case, the Gen-
eral Assembly has competence in any event to seise the Court. Indeed,
Article 10 of the Charter has conferred upon the General Assembly a
competence relating to “any questions or any matters” within the scope
of the Charter. Article 11 has specifically provided it with a competence
to “consider the general principles . . . in the maintenance of international
peace and security, including the principles governing disarmament and
the regulation of armaments”. Lastly, according to Article 13, the Gen-
eral Assembly “shall initiate studies and make recommendations for the
purpose of . . . encouraging the progressive development of international
law and its codification”.

12. The question put to the Court has a relevance to many aspects of
the activities and concerns of the General Assembly including those relat-
ing to the threat or use of force in international relations, the disarma-
ment process, and the progressive development of international law. The
General Assembly has a long-standing interest in these matters and in
their relation to nuclear weapons. This interest has been manifested in the
annual First Committee debates, and the Assembly resolutions on nuclear
weapons; in the holding of three special sessions on disarmament (1978,
1982 and 1988) by the General Assembly, and the annual meetings of the
Disarmament Commission since 1978; and also in the commissioning of
studies on the effects of the use of nuclear weapons. In this context, it
does not matter that important recent and current activities relating to
nuclear disarmament are being pursued in other fora.

Finally, Article 96, paragraph 1, of the Charter cannot be read as
limiting the ability of the Assembly to request an opinion only in those
circumstances in which it can take binding decisions. The fact that the
Assembly’s activities in the above-mentioned field have led it only to the
making of recommendations thus has no bearing on the issue of whether
it had the competence to put to the Court the question of which it is
seised.

13. The Court must furthermore satisfy itself that the advisory opinion
requested does indeed relate to a “legal question” within the meaning of
its Statute and the United Nations Charter.

The Court has already had occasion to indicate that questions

“framed in terms of law and rais[ing] problems of international law
... are by their very nature susceptible of a reply based on law...

11
234 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

[and] appear . . . to be questions of a legal character” (Western
Sahara, Advisory Opinion, 1. C.J. Reports 1975, p. 18, para. 15).

The question put to the Court by the General Assembly is indeed a
legal one, since the Court is asked to rule on the compatibility of the
threat or use of nuclear weapons with the relevant principles and rules of
international law. To do this, the Court must identify the existing prin-
ciples and rules, interpret them and apply them to the threat or use of
nuclear weapons, thus offering a reply to the question posed based on
law.

The fact that this question also has political aspects, as, in the nature
of things, is the case with so many questions which arise in international
life, does not suffice to deprive it of its character as a “legal question” and
to “deprive the Court of a competence expressly conferred on it by its
Statute” (Application for Review of Judgement No. 158 of the United
Nations Administrative Tribunal, Advisory Opinion, 1 C.J. Reports 1973,
p. 172, para. 14). Whatever its political aspects, the Court cannot refuse
to admit the legal character of a question which invites it to discharge an
essentially judicial task, namely, an assessment of the legality of the pos-
sible conduct of States with regard to the obligations imposed upon them
by international law (cf. Conditions of Admission of a State to Member-
ship in the United Nations (Article 4 of Charter), Advisory Opinion,
1948, I.C.J. Reports 1947-1948, pp. 61-62; Competence of the General
Assembly for the Admission of a State to the United Nations, Advisory
Opinion, I.C.J. Reports 1950, pp. 6-7; Certain Expenses of the United
Nations (Article 17, paragraph 2, of the Charter), Advisory Opinion,
LC J. Reports 1962, p. 155).

Furthermore, as the Court said in the Opinion it gave in 1980 concern-
ing the Interpretation of the Agreement of 25 March 1951 between the
WHO and Egypt:

“Indeed, in situations in which political considerations are promi-
nent it may be particularly necessary for an international organiza-
tion to obtain an advisory opinion from the Court as to the legal
principles applicable with respect to the matter under debate . . .”
(LCJ. Reports 1980, p. 87, para. 33.)

The Court moreover considers that the political nature of the motives
which may be said to have inspired the request and the political implica-
tions that the opinion given might have are of no relevance in the estab-
lishment of its jurisdiction to give such an opinion.

*

14. Article 65, paragraph 1, of the Statute provides: “The Court may
give an advisory opinion . . .” (Emphasis added.) This is more than an
enabling provision. As the Court has repeatedly emphasized, the Statute

12
235 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

leaves a discretion as to whether or not it will give an advisory opinion
that has been requested of it, once it has established its competence to do
so. In this context, the Court has previously noted as follows:

“The Court’s Opinion is given not to the States, but to the organ
which is entitled to request it; the reply of the Court, itself an ‘organ
of the United Nations’, represents its participation in the activities of
the Organization, and, in principle, should not be refused.” (Inter-
pretation of Peace Treaties with Bulgaria, Hungary and Romania,
First Phase, Advisory Opinion, I.C.J. Reports 1950, p. 71; see also
Reservations to the Convention on the Prevention and Punishment of
the Crime of Genocide, Advisory Opinion, .C.J. Reports 1951,
p. 19; Judgments of the Administrative Tribunal of the ILO upon
Complaints Made against Unesco, Advisory Opinion, I.C.J. Reports
1956, p. 86; Certain Expenses of the United Nations ( Article 17, para-
graph 2, of the Charter), Advisory Opinion, I C.J. Reports 1962,
p. 155; and Applicability of Article VI, Section 22, of the Convention
on the Privileges and Immunities of the United Nations, Advisory
Opinion, I. C.J. Reports 1989, p. 189.)

The Court has constantly been mindful of its responsibilities as “the
principal judicial organ of the United Nations” (Charter, Art. 92). When
considering each request, it is mindful that it should not, in principle,
refuse to give an advisory opinion. In accordance with the consistent
jurisprudence of the Court, only “compelling reasons” could lead it to
such a refusal (Judgments of the Administrative Tribunal of the ILO
upon Complaints Made against Unesco, Advisory Opinion, I.C.J. Reports
1956, p. 86; Certain Expenses of the United Nations (Article 17, para-
graph 2, of the Charter), Advisory Opinion, I.C.J. Reports 1962, p. 155;
Legal Consequences for States of the Continued Presence of South Africa
in Namibia (South West Africa) notwithstanding Security Council Reso-
lution 276 (1970), Advisory Opinion, I.C.J. Reports 1971, p. 27; Applica-
tion for Review of Judgement No. 158 of the United Nations Administra-
tive Tribunal, Advisory Opinion, I.C.J. Reports 1973, p. 183; Western
Sahara, Advisory Opinion, .C.J. Reports 1975, p. 21; and Applicability
of Article VI, Section 22, of the Convention on the Privileges and Immu-
nities of the United Nations, Advisory Opinion, I.C.J. Reports 1989,
p. 191). There has been no refusal, based on the discretionary power of
the Court, to act upon a request for advisory opinion in the history of the
present Court; in the case concerning the Legality of the Use by a State
of Nuclear Weapons in Armed Conflict, the refusal to give the World
Health Organization the advisory opinion requested by it was justified by
the Court’s lack of jurisdiction in that case. The Permanent Court of
International Justice took the view on only one occasion that it could not
reply to a question put to it, having regard to the very particular circum-
stances of the case, among which were that the question directly con-
cerned an already existing dispute, one of the States parties to which was

13
236 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

neither a party to the Statute of the Permanent Court nor a Member of
the League of Nations, objected to the proceedings, and refused to take
part in any way (Status of Eastern Carelia, P.C.I.J., Series B, No. 5).

15. Most of the reasons adduced in these proceedings in order to per-
suade the Court that in the exercise of its discretionary power it should
decline to render the opinion requested by General Assembly resolu-
tion 49/75 K were summarized in the following statement made by one
State in the written proceedings:

“The question presented is vague and abstract, addressing complex
issues which are the subject of consideration among interested States
and within other bodies of the United Nations which have an express
mandate to address these matters. An opinion by the Court in regard
to the question presented would provide no practical assistance to
the General Assembly in carrying out its functions under the Char-
ter. Such an opinion has the potential of undermining progress
already made or being made on this sensitive subject and, therefore,
is contrary to the interests of the United Nations Organization.”
(United States of America, Written Statement, pp. 1-2; cf. pp. 3-7, II.
See also United Kingdom, Written Statement, pp. 9-20, paras. 2.23-
2.45; France, Written Statement, pp. 13-20, paras. 5-9; Finland,
Written Statement, pp. 1-2; Netherlands, Written Statement, pp. 3-4,
paras. 6-13; Germany, Written Statement, pp. 3-6, para. 2 (b).)

In contending that the question put to the Court is vague and abstract,
some States appeared to mean by this that there exists no specific dispute
on the subject-matter of the question. In order to respond to this argu-
ment, it is necessary to distinguish between requirements governing con-
tentious procedure and those applicable to advisory opinions. The pur-
pose of the advisory function is not to settle — at least directly —
disputes between States, but to offer legal advice to the organs and insti-
tutions requesting the opinion (cf. Interpretation of Peace Treaties with
Bulgaria, Hungary and Romania, First Phase, Advisory Opinion, I.C_J.
Reports 1950, p. 71). The fact that the question put to the Court does not
relate to a specific dispute should consequently not lead the Court to
decline to give the opinion requested.

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

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237 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

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

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

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

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

18. Finally, it has been contended by some States that in answering the
question posed, the Court would be going beyond its judicial role and
would be taking upon itself a law-making capacity. It is clear that the
Court cannot legislate, and, in the circumstances of the present case, it is
not called upon to do so. Rather its task is to engage in its normal judi-
cial function of ascertaining the existence or otherwise of legal principles
and rules applicable to the threat or use of nuclear weapons. The conten-
tion that the giving of an answer to the question posed would require the
Court to legislate is based on a supposition that the present corpus juris is
devoid of relevant rules in this matter. The Court could not accede to this
argument; it states the existing law and does not legislate. This is so even
if, in stating and applying the law, the Court necessarily has to specify its
scope and sometimes note its general trend.

15
238 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

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

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

*% * %

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

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

21. The use of the word “permitted” in the question put by the Gen-
eral Assembly was criticized before the Court by certain States on the
ground that this implied that the threat or the use of nuclear weapons
would only be permissible if authorization could be found in a treaty pro-
vision or in customary international law. Such a starting point, those
States submitted, was incompatible with the very basis of international
law, which rests upon the principles of sovereignty and consent; accord-
ingly, and contrary to what was implied by use of the word “permitted”,
States are free to threaten or use nuclear weapons unless it can be shown
that they are bound not to do so by reference to a prohibition in either
treaty law or customary international law. Support for this contention
was found in dicta of the Permanent Court of International Justice in the
“Lotus” case that “restrictions upon the independence of States cannot
. . . be presumed” and that international law leaves to States “a wide
measure of discretion which is only limited in certain cases by prohibitive
rules” (P.C.I.J., Series A, No. 10, pp. 18 and 19). Reliance was also
placed on the dictum of the present Court in the case concerning Military
and Paramilitary Activities in and against Nicaragua (Nicaragua
v. United States of America) that:

“in international law there are no rules, other than such rules as may
be accepted by the State concerned, by treaty or otherwise, whereby

16
239 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

the level of armaments of a sovereign State can be limited” (Z C.J.
Reports 1986, p. 135, para. 269).

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

Finally, it was suggested that, were the Court to answer the question
put by the Assembly, the word “permitted” should be replaced by “pro-
hibited”.

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

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

* *

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

*

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

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

17
240 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

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

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

“any of the following acts committed with intent to destroy, in
whole or in part, a national, ethnical, racial or religious group, as
such:

(a) Killing members of the group;

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

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

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

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

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

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

18
241 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

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

Specific references were made to various existing international treaties
and instruments. These included Additional Protocol I of 1977 to the
Geneva Conventions of 1949, Article 35, paragraph 3, of which prohibits
the employment of “methods or means of warfare which are intended, or
may be expected, to cause widespread, long-term and severe damage to
the natural environment”; and the Convention of 18 May 1977 on the
Prohibition of Military or Any Other Hostile Use of Environmental
Modification Techniques, which prohibits the use of weapons which have
“widespread, long-lasting or severe effects” on the environment (Art. 1).
Also cited were Principle 21 of the Stockholm Declaration of 1972 and
Principle 2 of the Rio Declaration of 1992 which express the common
conviction of the States concerned that they have a duty

“to ensure that activities within their jurisdiction or control do not
cause damage to the environment of other States or of areas beyond
the limits of national jurisdiction”.

These instruments and other provisions relating to the protection and
safeguarding of the environment were said to apply at all times, in war as
well as in peace, and it was contended that they would be violated by the
use of nuclear weapons whose consequences would be widespread and
would have transboundary effects.

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

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

29. The Court recognizes that the environment is under daily threat
and that the use of nuclear weapons could constitute a catastrophe for
the environment. The Court also recognizes that the environment is not
an abstraction but represents the living space, the quality of life and
the very health of human beings, including generations unborn. The

19
242 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

existence of the general obligation of States to ensure that activities
within their jurisdiction and control respect the environment of other
States or of areas beyond national control is now part of the corpus
of international law relating to the environment.

30. However, the Court is of the view that the issue is not whether the
treaties relating to the protection of the environment are or are not appli-
cable during an armed conflict, but rather whether the obligations
stemming from these treaties were intended to be obligations of total
restraint during military conflict.

The Court does not consider that the treaties in question could have
intended to deprive a State of the exercise of its right of self-defence
under international law because of its obligations to protect the environ-
ment. Nonetheless, States must take environmental considerations into
account when assessing what is necessary and proportionate in the pur-
suit of legitimate military objectives. Respect for the environment is one
of the elements that go to assessing whether an action is in conformity
with the principles of necessity and proportionality.

This approach is supported, indeed, by the terms of Principle 24 of the
Rio Declaration, which provides that:

“Warfare is inherently destructive of sustainable development.
States shall therefore respect international law providing protection
for the environment in times of armed conflict and cooperate in its
further development, as necessary.”

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

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

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

20
243 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

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

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

*k

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

* *

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

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

The radiation released by a nuclear explosion would affect health,
agriculture, natural resources and demography over a very wide area.

21
244 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

Further, the use of nuclear weapons would be a serious danger to future
generations. Ionizing radiation has the potential to damage the future
environment, food and marine ecosystem, and to cause genetic defects
and illness in future generations.

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

37. The Court will now address the question of the legality or illegality
of recourse to nuclear weapons in the light of the provisions of the Char-
ter relating to the threat or use of force.

38. The Charter contains several provisions relating to the threat and
use of force. In Article 2, paragraph 4, the threat or use of force against
the territorial integrity or political independence of another State or in
any other manner inconsistent with the purposes of the United Nations is
prohibited. That paragraph provides:

“All Members shall refrain in their international relations from
the threat or use of force against the territorial integrity or political
independence of any State, or in any other manner inconsistent with
the Purposes of the United Nations.”

This prohibition of the use of force is to be considered in the light of
other relevant provisions of the Charter. In Article 51, the Charter
recognizes the inherent right of individual or collective self-defence if
an armed attack occurs. A further lawful use of force is envisaged in
Article 42, whereby the Security Council may take military enforcement
measures in conformity with Chapter VII of the Charter.

39. These provisions do not refer to specific weapons. They apply to
any use of force, regardless of the weapons employed. The Charter
neither expressly prohibits, nor permits, the use of any specific weapon,
including nuclear weapons. A weapon that is already unlawful per se,
whether by treaty or custom, does not become lawful by reason of its
being used for a legitimate purpose under the Charter.

40. The entitlement to resort to self-defence under Article 51 is subject

to certain constraints. Some of these constraints are inherent in the very
concept of self-defence. Other requirements are specified in Article 51.

22
245 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

41. The submission of the exercise of the right of self-defence to the
conditions of necessity and proportionality is a rule of customary inter-
national law. As the Court stated in the case concerning Military and
Paramilitary Activities in and against Nicaragua (Nicaragua v. United
States of America): there is a “specific rule whereby self-defence would
warrant only measures which are proportional to the armed attack and
necessary to respond to it, a rule well established in customary inter-
national law” (I. C.J. Reports 1986, p. 94, para. 176). This dual condition
applies equally to Article 51 of the Charter, whatever the means of force
employed.

42. The proportionality principle may thus not in itself exclude the use
of nuclear weapons in self-defence in all circumstances. But at the same
time, a use of force that is proportionate under the law of self-defence,
must, in order to be lawful, also meet the requirements of the law appli-
cable in armed conflict which comprise in particular the principles and
rules of humanitarian law.

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

44. Beyond the conditions of necessity and proportionality, Article 51
specifically requires that measures taken by States in the exercise of the
right of self-defence shall be immediately reported to the Security Coun-
cil; this article further provides that these measures shall not in any way
affect the authority and responsibility of the Security Council under the
Charter to take at any time such action as it deems necessary in order to
maintain or restore international peace and security. These requirements
of Article 51 apply whatever the means of force used in self-defence.

45. The Court notes that the Security Council adopted on 11 April
1995, in the context of the extension of the Treaty on the Non-Prolifera-
tion of Nuclear Weapons, resolution 984 (1995) by the terms of which, on
the one hand, it

“[t]akes note with appreciation of the statements made by each
of the nuclear-weapon States (S/1995/261, S/1995/262, S/1995/263,
S/1995/264, S/1995/265), in which they give security assurances

23
246 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

against the use of nuclear weapons to non-nuclear-weapon States
that are Parties to the Treaty on the Non-Proliferation of Nuclear
Weapons”,

and, on the other hand, it

“Tw Jelcomes the intention expressed by certain States that they will
provide or support immediate assistance, in accordance with the
Charter, to any non-nuclear-weapon State Party to the Treaty on the
Non-Proliferation of Nuclear Weapons that is a victim of an act of,
or an object of a threat of, aggression in which nuclear weapons are
used”.

46. Certain States asserted that the use of nuclear weapons in the con-
duct of reprisals would be lawful. The Court does not have to examine, in
this context, the question of armed reprisals in time of peace, which are
considered to be unlawful. Nor does it have to pronounce on the ques-
tion of belligerent reprisals 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.

47. In order to lessen or eliminate the risk of unlawful attack, States
sometimes signal that they possess certain weapons to use in self-defence
against any State violating their territorial integrity or political inde-
pendence. Whether a signalled intention to use force if certain events
occur is or is not a “threat” within Article 2, paragraph 4, of the Charter
depends upon various factors. If the envisaged use of force is itself un-
lawful, the stated readiness to use it would be a threat prohibited under
Article 2, paragraph 4. Thus it would be illegal for a State to threaten
force to secure territory from another State, or to cause it to follow or
not follow certain political or economic paths. The notions of “threat”
and “use” of force under Article 2, paragraph 4, of the Charter stand
together in the sense that if the use of force itself in a given case is illegal
— for whatever reason — the threat to use such force will likewise be
illegal. In short, if it is to be lawful, the declared readiness of a State to
use force must be a use of force that is in conformity with the Charter.
For the rest, no State — whether or not it defended the policy of deter-
rence — suggested to the Court that it would be lawful to threaten to use
force if the use of force contemplated would be illegal.

48. Some States put forward the argument that possession of nuclear
weapons is itself an unlawful threat to use force. Possession of nuclear
weapons may indeed justify an inference of preparedness to use them. In
order to be effective, the policy of deterrence, by which those States pos-
sessing or under the umbrella of nuclear weapons seek to discourage mili-
tary aggression by demonstrating that it will serve no purpose, necessi-
tates that the intention to use nuclear weapons be credible. Whether this

24
247 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

is a “threat” contrary to Article 2, paragraph 4, depends upon whether
the particular use of force envisaged would be directed against the terri-
torial integrity or political independence of a State, or against the Pur-
poses 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. In any of these circumstances the use of
force, and the threat to use it, would be unlawful under the law of the
Charter.

49. Moreover, the Security Council may take enforcement measures
under Chapter VII of the Charter. From the statements presented to it
the Court does not consider it necessary to address questions which
might, in a given case, arise from the application of Chapter VII.

50. The terms of the question put to the Court by the General Assem-
bly in resolution 49/75 K could in principle also cover a threat or use of
nuclear weapons by a State within its own boundaries. However, this
particular aspect has not been dealt with by any of the States which
addressed the Court orally or in writing in these proceedings. The Court
finds that it is not called upon to deal with an internal use of nuclear
weapons.

x *

51. Having dealt with the Charter provisions relating to the threat or
use of force, the Court will now turn to the law applicable in situations of
armed conflict. It will first address the question whether there are specific
rules in international law regulating the legality or illegality of recourse to
nuclear weapons per se; it will then examine the question put to it in the
light of the law applicable in armed conflict proper, 1.e. the principles and
rules of humanitarian law applicable in armed conflict, and the law of
neutrality.

*  *%

52. The Court notes by way of introduction that international custom-
ary and treaty law does not contain any specific prescription authorizing
the threat or use of nuclear weapons or any other weapon in general or in
certain circumstances, in particular those of the exercise of legitimate self-
defence. Nor, however, is there any principle or rule of international law
which would make the legality of the threat or use of nuclear weapons or
of any other weapons dependent on a specific authorization. State prac-
tice shows that the illegality of the use of certain weapons as such does
not result from an absence of authorization but, on the contrary, is
formulated in terms of prohibition.

25
248 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

53. The Court must therefore now examine whether there is any pro-
hibition of recourse to nuclear weapons as such; it will first ascertain
whether there is a conventional prescription to this effect.

54. In this regard, the argument has been advanced that nuclear
weapons should be treated in the same way as poisoned weapons. In that
case, they would be prohibited under:

(a) the Second Hague Declaration of 29 July 1899, which prohibits “the
use of projectiles the object of which is the diffusion of asphyxiating
or deleterious gases” ;

(b) Article 23 (a) of the Regulations respecting the laws and customs of
war on land annexed to the Hague Convention IV of 18 October
1907, whereby “it is especially forbidden: . . . to employ poison or
poisoned weapons”; and

{c) the Geneva Protocol of 17 June 1925 which prohibits “the use in war
of asphyxiating, poisonous or other gases, and of all analogous
liquids, materials or devices”.

55. The Court will observe that the Regulations annexed to the Hague
Convention IV do not define what is to be understood by “poison or
poisoned weapons” and that different interpretations exist on the issue.
Nor does the 1925 Protocol specify the meaning to be given to the term
“analogous materials or devices”. The terms have been understood, in
the practice of States, in their ordinary sense as covering weapons whose
prime, or even exclusive, effect is to poison or asphyxiate. This practice is
clear, and the parties to those instruments have not treated them as refer-
ring to nuclear weapons.

56. In view of this, it does not seem to the Court that the use of
nuclear weapons can be regarded as specifically prohibited on the basis of
the above-mentioned provisions of the Second Hague Declaration of
1899, the Regulations annexed to the Hague Convention IV of 1907 or
the 1925 Protocol (see paragraph 54 above).

57. The pattern until now has been for weapons of mass destruction to
be declared illegal by specific instruments. The most recent such instru-
ments are the Convention of 10 April 1972 on the Prohibition of the
Development, Production and Stockpiling of Bacteriological (Biological)
and Toxin Weapons and on Their Destruction — which prohibits the
possession of bacteriological and toxic weapons and reinforces the pro-
hibition of their use — and the Convention of 13 January 1993 on the
Prohibition of the Development, Production, Stockpiling and Use of
Chemical Weapons and on Their Destruction — which prohibits all use
of chemical weapons and requires the destruction of existing stocks. Each
of these instruments has been negotiated and adopted in its own context
and for its own reasons. The Court does not find any specific prohibition
of recourse to nuclear weapons in treaties expressly prohibiting the use of
certain weapons of mass destruction.

58. In the last two decades, a great many negotiations have been con-
ducted regarding nuclear weapons; they have not resulted in a treaty of

26
249 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

general prohibition of the same kind as for bacteriological and chemical
weapons. However, a number of specific treaties have been concluded in
order to limit:

(a) the acquisition, manufacture and possession of nuclear weapons
(Peace Treaties of 10 February 1947; State Treaty for the Re-estab-
lishment of an Independent and Democratic Austria of 15 May
1955; Treaty of Tlatelolco of 14 February 1967 for the Prohibition
of Nuclear Weapons in Latin America, and its Additional Proto-
cols; Treaty of 1 July 1968 on the Non-Proliferation of Nuclear
Weapons; Treaty of Rarotonga of 6 August 1985 on the Nuclear-
Weapon-Free Zone of the South Pacific, and its Protocols; Treaty of
12 September 1990 on the Final Settlement with respect to Germany);

(b) the deployment of nuclear weapons (Antarctic Treaty of 1 December
1959; Treaty of 27 January 1967 on Principles Governing the Activi-
ties of States in the Exploration and Use of Outer Space, including
the Moon and Other Celestial Bodies; Treaty of Tlatelolco of 14 Feb-
ruary 1967 for the Prohibition of Nuclear Weapons in Latin America,
and its Additional Protocols; Treaty of 11 February 1971 on the
Prohibition of the Emplacement of Nuclear Weapons and Other
Weapons of Mass Destruction on the Sea-Bed and the Ocean Floor
and in the Subsoil Thereof; Treaty of Rarotonga of 6 August 1985
on the Nuclear-Weapon-Free Zone of the South Pacific, and its Pro-
tocols); and

(c) the testing of nuclear weapons (Antarctic Treaty of 1 December
1959; Treaty of 5 August 1963 Banning Nuclear Weapon Tests in
the Atmosphere, in Outer Space and under Water; Treaty of 27 Jan-
uary 1967 on Principles Governing the Activities of States in the
Exploration and Use of Outer Space, including the Moon and Other
Celestial Bodies; Treaty of Tlatelolco of 14 February 1967 for the
Prohibition of Nuclear Weapons in Latin America, and its Addi-
tional Protocols; Treaty of Rarotonga of 6 August 1985 on the
Nuclear-Weapon-Free Zone of the South Pacific, and its Protocols).

59. Recourse to nuclear weapons is directly addressed by two of these
Conventions and also in connection with the indefinite extension of the
Treaty on the Non-Proliferation of Nuclear Weapons of 1968:

(a) the Treaty of Tlatelolco of 14 February 1967 for the Prohibition of
Nuclear Weapons in Latin America prohibits, in Article 1, the use of
nuclear weapons by the Contracting Parties. It further includes an
Additional Protocol II open to nuclear-weapon States outside the
region, Article 3 of which provides:

“The Governments represented by the undersigned Plenipo-
tentiaries also undertake not to use or threaten to use nuclear
weapons against the Contracting Parties of the Treaty for the
Prohibition of Nuclear Weapons in Latin America.”

27
250

(b)

28

THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

The Protocol was signed and ratified by the five nuclear-weapon
States. Its ratification was accompanied by a variety of declarations.
The United Kingdom Government, for example, stated that “in the
event of any act of aggression by a Contracting Party to the Treaty
in which that Party was supported by a nuclear-weapon State”, the
United Kingdom Government would “be free to reconsider the
extent to which they could be regarded as committed by the provi-
sions of Additional Protocol II”. The United States made a similar
statement. The French Government, for its part, stated that it “inter-
prets the undertaking made in article 3 of the Protocol as being with-
out prejudice to the full exercise of the right of self-defence con-
firmed by Article 51 of the Charter”. China reaffirmed its commit-
ment not to be the first to make use of nuclear weapons. The Soviet
Union reserved “the right to review” the obligations imposed upon it
by Additional Protocol IL, particularly in the event of an attack by a
State party either “in support of a nuclear-weapon State or jointly
with that State”. None of these statements drew comment or objec-
tion from the parties to the Treaty of Tlatelolco.

the Treaty of Rarotonga of 6 August 1985 establishes a South
Pacific Nuclear Free Zone in which the Parties undertake not to
manufacture, acquire or possess any nuclear explosive device
(Art. 3). Unlike the Treaty of Tlatelolco, the Treaty of Rarotonga
does not expressly prohibit the use of such weapons. But such a pro-
hibition is for the States parties the necessary consequence of the
prohibitions stipulated by the Treaty. The Treaty has a number of
protocols. Protocol 2, open to the five nuclear-weapon States, speci-
fies in its Article 1 that:

“Each Party undertakes not to use or threaten to use any
nuclear explosive device against:

(a) Parties to the Treaty; or

(b) any territory within the South Pacific Nuclear Free Zone for
which a State that has become a Party to Protocol 1 is inter-
nationally responsible.”

China and Russia are parties to that Protocol. In signing it, China
and the Soviet Union each made a declaration by which they reserved
the “right to reconsider” their obligations under the said Protocol;
the Soviet Union also referred to certain circumstances in which it
would consider itself released from those obligations. France, the
United Kingdom and the United States, for their part, signed Pro-
tocol 2 on 25 March 1996, but have not yet ratified it. On that occa-
sion, France declared, on the one hand, that no provision in that
Protocol “shall impair the full exercise of the inherent right of self-
defence provided for in Article 51 of the . . . Charter” and, on the
other hand, that “the commitment set out in Article 1 of [that] Pro-
tocol amounts to the negative security assurances given by France to
251

(ce)

29

THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

non-nuclear-weapon States which are parties to the Treaty on...
Non-Proliferation”, and that “these assurances shall not apply to
States which are not parties” to that Treaty. For its part, the United
Kingdom made a declaration setting out the precise circumstances in
which it “will not be bound by [its] undertaking under Article 1” of
the Protocol.

as to the Treaty on the Non-Proliferation of Nuclear Weapons, at
the time of its signing in 1968 the United States, the United King-
dom and the USSR gave various security assurances to the non-
nuclear-weapon States that were parties to the Treaty. In resolu-
tion 255 (1968) the Security Council took note with satisfaction of
the intention expressed by those three States to

“provide or support immediate assistance, in accordance with the
Charter, to any non-nuclear-weapon State Party to the Treaty on
the Non-Proliferation . . . that is a victim of an act of, or an object
of a threat of, aggression in which nuclear weapons are used”.

On the occasion of the extension of the Treaty in 1995, the five
nuclear-weapon States gave their non-nuclear-weapon partners, by
means of separate unilateral statements on 5 and 6 April 1995,
positive and negative security assurances against the use of such
weapons. All the five nuclear-weapon States first undertook not to
use nuclear weapons against non-nuclear-weapon States that were
parties to the Treaty on the Non-Proliferation of Nuclear Weap-
ons. However, these States, apart from China, made an exception
in the case of an invasion or any other attack against them, their
territories, armed forces or allies, or on a State towards which they
had a security commitment, carried out or sustained by a non-
nuclear-weapon State party to the Non-Proliferation Treaty in
association or alliance with a nuclear-weapon State. Each of the
nuclear-weapon States further undertook, as a permanent member
of the Security Council, in the event of an attack with the use of
nuclear weapons, or threat of such attack, against a non-nuclear-
weapon State, to refer the matter to the Security Council without
delay and to act within it in order that it might take immediate
measures with a view to supplying, pursuant to the Charter, the
necessary assistance to the victim State (the commitments assumed
comprising minor variations in wording). The Security Council, in
unanimously adopting resolution 984 (1995) of 11 April 1995, cited
above, took note of those statements with appreciation. It also
recognized

“that the nuclear-weapon State permanent members of the Secu-
rity Council will bring the matter immediately to the attention of
the Council and seek Council action to provide, in accordance
with the Charter, the necessary assistance to the State victim”;
252 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

and welcomed the fact that

“the intention expressed by certain States that they will provide or
support immediate assistance, in accordance with the Charter, to
any non-nuclear-weapon State Party to the Treaty on the Non-
Proliferation of Nuclear Weapons that is a victim of an act of, or
an object of a threat of, aggression in which nuclear weapons are
used”.

60. Those States that believe that recourse to nuclear weapons is illegal
stress that the conventions that include various rules providing for the
limitation or elimination of nuclear weapons in certain areas (such as the
Antarctic Treaty of 1959 which prohibits the deployment of nuclear
weapons in the Antarctic, or the Treaty of Tlatelolco of 1967 which cre-
ates a nuclear-weapon-free zone in Latin America) or the conventions
that apply certain measures of control and limitation to the existence of
nuclear weapons (such as the 1963 Partial Test-Ban Treaty or the Treaty
on the Non-Proliferation of Nuclear Weapons) all set limits to the use of
nuclear weapons. In their view, these treaties bear witness, in their own
way, to the emergence of a rule of complete legal prohibition of all uses
of nuclear weapons.

61. Those States who defend the position that recourse to nuclear
weapons is legal in certain circumstances see a logical contradiction in
reaching such a conclusion. According to them, those Treaties, such as
the Treaty on the Non-Proliferation of Nuclear Weapons, as well as
Security Council resolutions 255 (1968) and 984 (1995) which take note
of the security assurances given by the nuclear-weapon States to the non-
nuclear-weapon States in relation to any nuclear aggression against the
latter, cannot be understood as prohibiting the use of nuclear weapons,
and such a claim is contrary to the very text of those instruments. For
those who support the legality in certain circumstances of recourse to
nuclear weapons, there is no absolute prohibition against the use of such
weapons. The very logic and construction of the Treaty on the Non-Pro-
liferation of Nuclear Weapons, they assert, confirm this. This Treaty,
whereby, they contend, the possession of nuclear weapons by the five
nuclear-weapon States has been accepted, cannot be seen as a treaty ban-
ning their use by those States; to accept the fact that those States possess
nuclear weapons is tantamount to recognizing that such weapons may be
used in certain circumstances. Nor, they contend, could the security
assurances given by the nuclear-weapon States in 1968, and more recently
in connection with the Review and Extension Conference of the Parties
to the Treaty on the Non-Proliferation of Nuclear Weapons in 1995,
have been conceived without its being supposed that there were circum-
stances in which nuclear weapons could be used in a lawful manner. For
those who defend the legality of the use, in certain circumstances, of
nuclear weapons, the acceptance of those instruments by the different
non-nuclear-weapon States confirms and reinforces the evident logic
upon which those instruments are based.

30
253 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

62. The Court notes that the treaties dealing exclusively with acquisi-
tion, manufacture, possession, deployment and testing of nuclear
weapons, without specifically addressing their threat or use, certainly
point to an increasing concern in the international community with these
weapons; the Court concludes from this that these treaties could there-
fore be seen as foreshadowing a future general prohibition of the use
of such weapons, but they do not constitute such a prohibition by them-
selves. As to the treaties of Tlatelolco and Rarotonga and their Protocols,
and also the declarations made in connection with the indefinite extension
of the Treaty on the Non-Proliferation of Nuclear Weapons, it emerges
from these instruments that:

(a) a number of States have undertaken not to use nuclear weapons in
specific zones (Latin America; the South Pacific) or against certain
other States (non-nuclear-weapon States which are parties to the
Treaty on the Non-Proliferation of Nuclear Weapons);

(6) nevertheless, even within this framework, the nuclear-weapon States
have reserved the right to use nuclear weapons in certain circum-
stances; and

(c) these reservations met with no objection from the parties to the
Tlatelolco or Rarotonga Treaties or from the Security Council.

63. These two treaties, the security assurances given in 1995 by the
nuclear-weapon States and the fact that the Security Council took note of
them with satisfaction, testify to a growing awareness of the need to
liberate the community of States and the international public from the
dangers resulting from the existence of nuclear weapons. The Court more-
over notes the signing, even more recently, on 15 December 1995, at
Bangkok, of a Treaty on the Southeast Asia Nuclear-Weapon-Free Zone,
and on 11 April 1996, at Cairo, of a treaty on the creation of a nuclear-
weapons-free zone in Africa. It does not, however, view these elements as
amounting to a comprehensive and universal conventional prohibition
on the use, or the threat of use, of those weapons as such.

*

64. The Court will now turn to an examination of customary interna-
tional law to determine whether a prohibition of the threat or use of
nuclear weapons as such flows from that source of law. As the Court has
stated, the substance of that law must be “looked for primarily in the
actual practice and opinio juris of States” (Continental Shelf (Libyan
Arab Jamahiriya/Malta), Judgment, I.C.J. Reports 1985, p. 29,
para. 27).

65. States which hold the view that the use of nuclear weapons is ille-
gal have endeavoured to demonstrate the existence of a customary rule
prohibiting this use. They refer to a consistent practice of non-utilization
of nuclear weapons by States since 1945 and they would see in that prac-

31
254 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

tice the expression of an opinio juris on the part of those who possess
such weapons.

66. Some other States, which assert the legality of the threat and use of
nuclear weapons in certain circumstances, invoked the doctrine and prac-
tice of deterrence in support of their argument. They recall that they have
always, in concert with certain other States, reserved the right to use
those weapons in the exercise of the right to self-defence against an
armed attack threatening their vital security interests. In their view, if
nuclear weapons have not been used since 1945, it is not on account of an
existing or nascent custom but merely because circumstances that might
justify their use have fortunately not arisen.

67. The Court does not intend to pronounce here upon the practice
known as the “policy of deterrence”. It notes that it is a fact that a
number of States adhered to that practice during the greater part of the
Cold War and continue to adhere to it. Furthermore, the members of the
international community are profoundly divided on the matter of whether
non-recourse to nuclear weapons over the past 50 years constitutes the
expression of an opinio juris. Under these circumstances the Court does
not consider itself able to find that there is such an opinio juris.

68. According to certain States, the important series of General Assem-
bly resolutions, beginning with resolution 1653 (XVI) of 24 November
1961, that deal with nuclear weapons and that affirm, with consistent
regularity, the illegality of nuclear weapons, signify the existence of a
rule of international customary law which prohibits recourse to those
weapons. According to other States, however, the resolutions in question
have no binding character on their own account and are not declaratory
of any customary rule of prohibition of nuclear weapons; some of these
States have also pointed out that this series of resolutions not only did
not meet with the approval of all of the nuclear-weapon States but of
many other States as well.

69. States which consider that the use of nuclear weapons is illegal
indicated that those resolutions did not claim to create any new rules, but
were confined to a confirmation of customary law relating to the prohibi-
tion of means or methods of warfare which, by their use, overstepped the
bounds of what is permissible in the conduct of hostilities. In their view,
the resolutions in question did no more than apply to nuclear weapons
the existing rules of international law applicable in armed conflict; they
were no more than the “envelope” or instrumentum containing certain
pre-existing customary rules of international law. For those States it is
accordingly of little importance that the instrumentum should have occa-
sioned negative votes, which cannot have the effect of obliterating those
customary rules which have been confirmed by treaty law.

70. The Court notes that General Assembly resolutions, even if they
are not binding, may sometimes have normative value. They can, in cer-
tain circumstances, provide evidence important for establishing the exist-

32
255 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

ence of a rule or the emergence of an opinio juris. To establish whether
this is true of a given General Assembly resolution, it is necessary to look
at its content and the conditions of its adoption; it is also necessary to see
whether an opinio juris exists as to its normative character. Or a series of
resolutions may show the gradual evolution of the opinio juris required
for the establishment of a new rule.

71. Examined in their totality, the General Assembly resolutions put
before the Court declare that the use of nuclear weapons would be “a
direct violation of the Charter of the United Nations”; and in certain for-
mulations that such use “should be prohibited”. The focus of these reso-
lutions has sometimes shifted to diverse related matters; however, several
of the resolutions under consideration in the present case have been
adopted with substantial numbers of negative votes and abstentions;
thus, although those resolutions are a clear sign of deep concern regard-
ing the problem of nuclear weapons, they still fall short of establish-
ing the existence of an opinio juris on the illegality of the use of such
weapons.

72. The Court further notes that the first of the resolutions of the Gen-
eral Assembly expressly proclaiming the illegality of the use of nuclear
weapons, resolution 1653 (XVI) of 24 November 1961 (mentioned in sub-
sequent resolutions), after referring to certain international declarations
and binding agreements, from the Declaration of St. Petersburg of 1868
to the Geneva Protocol of 1925, proceeded to qualify the legal nature of
nuclear weapons, determine their effects, and apply general rules of cus-
tomary international law to nuclear weapons in particular. That applica-
tion by the General Assembly of general rules of customary law to the
particular case of nuclear weapons indicates that, in its view, there was
no specific rule of customary law which prohibited the use of nuclear
weapons; if such a rule had existed, the General Assembly could simply
have referred to it and would not have needed to undertake such an exer-
cise of legal qualification.

73. Having said this, the Court points out that the adoption each year
by the General Assembly, by a large majority, of resolutions recalling the
content of resolution 1653 (XVI), and requesting the member States to
conclude a convention prohibiting the use of nuclear weapons in any cir-
cumstance, reveals the desire of a very large section of the international
community to take, by a specific and express prohibition of the use of
nuclear weapons, a significant step forward along the road to complete
nuclear disarmament. The emergence, as /ex lata, of a customary rule
specifically prohibiting the use of nuclear weapons as such is hampered
by the continuing tensions between the nascent opinio juris on the one
hand, and the still strong adherence to the practice of deterrence on the
other.

33
256 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

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

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

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

77. All this shows that the conduct of military operations is governed
by a body of legal prescriptions. This is so because “the right of belli-
gerents to adopt means of injuring the enemy is not unlimited” as stated
in Article 22 of the 1907 Hague Regulations relating to the laws and
customs of war on land. The St. Petersburg Declaration had already
condemned the use of weapons “which uselessly aggravate the suffering of

34
257 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

disabled men or make their death inevitable”. The aforementioned Regu-
lations relating to the laws and customs of war on land, annexed to the
Hague Convention IV of 1907, prohibit the use of “arms, projectiles, or
material calculated to cause unnecessary suffering” (Art. 23).

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

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

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

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

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

35
258 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

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

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

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

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

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

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

36
259 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

84. Nor is there any need for the Court to elaborate on the question of
the applicability of Additional Protocol I of 1977 to nuclear weapons. It
need only observe that while, at the Diplomatic Conference of 1974-1977,
there was no substantive debate on the nuclear issue and no specific solu-
tion concerning this question was put forward, Additional Protocol I in
no way replaced the general customary rules applicable to all means and
methods of combat including nuclear weapons. In particular, the Court
recalls that all States are bound by those rules in Additional Protocol I
which, when adopted, were merely the expression of the pre-existing
customary law, such as the Martens Clause, reaffirmed in the first
article of Additional Protocol I. The fact that certain types of weapons
were not specifically dealt with by the 1974-1977 Conference does not
permit the drawing of any legal conclusions relating to the substantive
issues which the use of such weapons would raise.

85. Turning now to the applicability of the principles and rules of
humanitarian law to a possible threat or use of nuclear weapons, the
Court notes that doubts in this respect have sometimes been voiced on
the ground that these principles and rules had evolved prior to the inven-
tion of nuclear weapons and that the Conferences of Geneva of 1949 and
1974-1977 which respectively adopted the four Geneva Conventions of
1949 and the two Additional Protocols thereto did not deal with nuclear
weapons specifically. Such views, however, are only held by a small
minority. In the view of the vast majority of States as well as writers there
can be no doubt as to the applicability of humanitarian law to nuclear
weapons.

86. The Court shares that view. Indeed, nuclear weapons were invented
after most of the principles and rules of humanitarian law applicable in
armed conflict had already come into existence; the Conferences of 1949
and 1974-1977 left these weapons aside, and there is a qualitative as well
as quantitative difference between nuclear weapons and all conventional
arms. However, it cannot be concluded from this that the established
principles and rules of humanitarian law applicable in armed conflict did
not apply to nuclear weapons. Such a conclusion would be incompatible
with the intrinsically humanitarian character of the legal principles in
question which permeates the entire law of armed conflict and applies to
all forms of warfare and to all kinds of weapons, those of the past, those
of the present and those of the future. In this respect it seems significant
that the thesis that the rules of humanitarian law do not apply to the new
weaponry, because of the newness of the latter, has not been advocated
in the present proceedings. On the contrary, the newness of nuclear
weapons has been expressly rejected as an argument against the applica-
tion to them of international humanitarian law:

“In general, international humanitarian law bears on the threat or
use of nuclear weapons as it does of other weapons.

37
260 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

International humanitarian law has evolved to meet contempo-
rary circumstances, and is not limited in its application to weaponry
of an earlier time. The fundamental principles of this law endure:
to mitigate and circumscribe the cruelty of war for humanitarian
reasons.” (New Zealand, Written Statement, p. 15, paras. 63-64.)

None of the statements made before the Court in any way advocated a
freedom to use nuclear weapons without regard to humanitarian con-
straints. Quite the reverse; it has been explicitly stated,

“Restrictions set by the rules applicable to armed conflicts in
respect of means and methods of warfare definitely also extend to
nuclear weapons” (Russian Federation, CR 95/29, p. 52);

“So far as the customary law of war is concerned, the United
Kingdom has always accepted that the use of nuclear weapons is
subject to the general principles of the jus in bello” (United King-
dom, CR 95/34, p. 45);

and

“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” (United States of America, CR 95/34,
p. 85).

87. Finally, the Court points to the Martens Clause, whose continuing
existence and applicability is not to be doubted, as an affirmation that the
principles and rules of humanitarian law apply to nuclear weapons.

*

88. The Court will now turn to the principle of neutrality which was
raised by several States. In the context of the advisory proceedings
brought before the Court by the WHO concerning the Legality of the
Use by a State of Nuclear Weapons in Armed Conflict, the position was
put as follows by one State:

“The principle .of neutrality, in its classic sense, was aimed at pre-
venting the incursion of belligerent forces into neutral territory, or
attacks on the persons or ships of neutrals. Thus: ‘the territory of
neutral powers is inviolable’ (Article 1 of the Hague Convention (V)
Respecting the Rights and Duties of Neutral Powers and Persons in
Case of War on Land, concluded on 18 October 1907); ‘belligerents
are bound to respect the sovereign rights of neutral powers . . ?
(Article 1 to the Hague Convention (XIII) Respecting the Rights and
Duties of Neutral Powers in Naval War, concluded on 18 October
1907), ‘neutral states have equal interest in having their rights
respected by belligerents . . .” (Preamble to Convention on Maritime

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261 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

Neutrality, concluded on 20 February 1928). It is clear, however,
that the principle of neutrality applies with equal force to trans-
border incursions of armed forces and to the transborder damage
caused to a neutral State by the use of a weapon in a belligerent
State.” (Nauru, Written Statement (1), p. 35, IV E.)

The principle so circumscribed is presented as an established part of the
customary international law.

89. The Court finds that as in the case of the principles of humanitar-
ian law applicable in armed conflict, international law leaves no doubt
that the principle of neutrality, whatever its content, which is of a fun-
damental character similar to that of the humanitarian principles and
rules, is applicable (subject to the relevant provisions of the United
Nations Charter), to all international armed conflict, whatever type of
weapons might be used.

*

90. Although the applicability of the principles and rules of humani-
tarian law and of the principle of neutrality to nuclear weapons is hardly
disputed, the conclusions to be drawn from this applicability are, on the
other hand, controversial.

91. According to one point of view, the fact that recourse to nuclear
weapons is subject to and regulated by the law of armed conflict does not
necessarily mean that such recourse is as such prohibited. As one State
put it to the Court:

“Assuming that a State’s use of nuclear weapons meets the require-
ments of self-defence, it must then be considered whether it con-
forms to the fundamental principles of the law of armed conflict
regulating the conduct of hostilities” (United Kingdom, Written
Statement, p. 40, para. 3.44);

“the legality of the use of nuclear weapons must therefore be assessed
in the light of the applicable principles of international law regarding
the use of force and the conduct of hostilities, as is the case with
other methods and means of warfare” (ibid., p. 75, para. 4.2 (3));

and

“The reality . . . is that nuclear weapons might be used in a wide
variety of circumstances with very different results in terms of likely
civilian casualties. In some cases, such as the use of a low yield
nuclear weapon against warships on the High Seas or troops in
sparsely populated areas, it is possible to envisage a nuclear attack
which caused comparatively few civilian casualties. It is by no means
the case that every use of nuclear weapons against a military objec-
tive would inevitably cause very great collateral civilian casualties.”

39
262 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

Ubid., p. 53, para. 3.70; see also United States of America, CR 95/
34, pp. 89-90.)

92. Another view holds that recourse to nuclear weapons could never
be compatible with the principles and rules of humanitarian law and is
therefore prohibited. In the event of their use, nuclear weapons would in
all circumstances be unable to draw any distinction between the civilian
population and combatants, or between civilian objects and military
objectives, and their effects, largely uncontrollable, could not be restricted,
either in time or in space, to lawful military targets. Such weapons would
kill and destroy in a necessarily indiscriminate manner, on account of the
blast, heat and radiation occasioned by the nuclear explosion and the
effects induced; and the number of casualties which would ensue would
be enormous. The use of nuclear weapons would therefore be prohibited
in any circumstance, notwithstanding the absence of any explicit conven-
tional prohibition. That view lay at the basis of the assertions by certain
States before the Court that nuclear weapons are by their nature illegal
under customary international law, by virtue of the fundamental prin-
ciple of humanity.

93. A similar view has been expressed with respect to the effects of the
principle of neutrality. Like the principles and rules of humanitarian law,
that principle has therefore been considered by some to rule out the use
of a weapon the effects of which simply cannot be contained within the
territories of the contending States.

94. The Court would observe that none of the States advocating the
legality of the use of nuclear weapons under certain circumstances,
including the “clean” use of smaller, low yield, tactical nuclear weapons,
has indicated what, supposing such limited use were feasible, would be
the precise circumstances justifying such use; nor whether such limited
use would not tend to escalate into the all-out use of high yield nuclear
weapons. This being so, the Court does not consider that it has a suffi-
cient basis for a determination on the validity of this view.

95. Nor can the Court make a determination on the validity of the
view that the recourse to nuclear weapons would be illegal in any circum-
stance owing to their inherent and total incompatibility with the law
applicable in armed conflict. Certainly, as the Court has already indi-
cated, the principles and rules of law applicable in armed conflict — at
the heart of which is the overriding consideration of humanity — make
the conduct of armed hostilities subject to a number of strict require-
ments. Thus, 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, to which the Court has referred
above, the use of such weapons in fact seems scarcely reconcilable with
respect for such requirements. Nevertheless, the Court considers that it

40
263 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

does not have sufficient elements to enable it to conclude with certainty
that the use of nuclear weapons would necessarily be at variance with the
principles and rules of law applicable in armed conflict in any circum-
stance.

96. Furthermore, the Court cannot lose sight of the fundamental right
of every State to survival, and thus its right to resort to self-defence, in
accordance with Article 51 of the Charter, when its survival is at stake.

Nor can it ignore the practice referred to as “policy of deterrence”, to
which an appreciable section of the international community adhered for
many years. The Court also notes the reservations which certain nuclear-
weapon States have appended to the undertakings they have given,
notably under the Protocols to the Treaties of Tlatelolco and Rarotonga,
and also under the declarations made by them in connection with the
extension of the Treaty on the Non-Proliferation of Nuclear Weapons,
not to resort to such weapons.

97. Accordingly, in view of the present state of international law
viewed as a whole, as examined above by the Court, and of the elements
of fact at its disposal, the Court is led to observe that it cannot reach a
definitive conclusion as to the legality or illegality of the use of nuclear
weapons by a State in an extreme circumstance of self-defence, in which
its very survival would be at stake.

*
* *

98. Given the eminently difficult issues that arise in applying the law
on the use of force and above all the law applicable in armed conflict to
nuclear weapons, the Court considers that it now needs to examine one
further aspect of the question before it, seen in a broader context.

In the long run, international law, and with it the stability of the inter-
national order which it is intended to govern, are bound to suffer from
the continuing difference of views with regard to the legal status of
weapons as deadly as nuclear weapons. It is consequently important to
put an end to this state of affairs: the long-promised complete nuclear
disarmament appears to be the most appropriate means of achieving
that result.

99. In these circumstances, the Court appreciates the full importance
of the recognition by Article VI of the Treaty on the Non-Proliferation of
Nuclear Weapons of an obligation to negotiate in good faith a nuclear
disarmament. This provision is worded as follows:

“Each of the Parties to the Treaty undertakes to pursue negotia-
tions in good faith on effective measures relating to cessation of the
nuclear arms race at an early date and to nuclear disarmament, and
on a treaty on general and complete disarmament under strict and
effective international control.”

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264 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

The legal import of that obligation goes beyond that of a mere obligation
of conduct; the obligation involved here is an obligation to achieve a pre-
cise result — nuclear disarmament in all its aspects — by adopting a par-
ticular course of conduct, namely, the pursuit of negotiations on the
matter in good faith.

100. This twofold obligation to pursue and to conclude negotiations
formally concerns the 182 States parties to the Treaty on the Non-
Proliferation of Nuclear Weapons, or, in other words, the vast majority
of the international community.

Virtually the whole of this community appears moreover to have been
involved when resolutions of the United Nations Genera] Assembly con-
cerning nuclear disarmament have repeatedly been unanimously adopted.
Indeed, any realistic search for general and complete disarmament, espe-
cially nuclear disarmament, necessitates the co-operation of all States.

101. Even the very first General Assembly resolution, unanimously
adopted on 24 January 1946 at the London session, set up a commission
whose terms of reference included making specific proposals for, among
other things, “the elimination from national armaments of atomic
weapons and of all other major weapons adaptable to mass destruction”.
In a large number of subsequent resolutions, the General Assembly has re-
affirmed the need for nuclear disarmament. Thus, in resolution 808 A (IX)
of 4 November 1954, which was likewise unanimously adopted, it con-
cluded

“that a further effort should be made to reach agreement on com-
prehensive and co-ordinated proposals to be embodied in a draft
international disarmament convention providing for: ... (b) The
total prohibition of the use and manufacture of nuclear weapons
and weapons of mass destruction of every type, together with the
conversion of existing stocks of nuclear weapons for peaceful pur-
poses.”

The same conviction has been expressed outside the United Nations
context in various instruments.

102. The obligation expressed in Article VI of the Treaty on the Non-
Proliferation of Nuclear Weapons includes its fulfilment in accordance
with the basic principle of good faith. This basic principle is set forth in
Article 2, paragraph 2, of the Charter. It was reflected in the Declaration
on Friendly Relations between States (resolution 2625 (XXV) of 24 Octo-
ber 1970) and in the Final Act of the Helsinki Conference of 1 August
1975. It is also embodied in Article 26 of the Vienna Convention on the
Law of Treaties of 23 May 1969, according to which “[elvery treaty in
force is binding upon the parties to it and must be performed by them in
good faith”.

Nor has the Court omitted to draw attention to it, as follows:

“One of the basic principles governing the creation and perform-

42
265 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

ance of legal obligations, whatever their source, is the principle of good
faith. Trust and confidence are inherent in international co-operation,
in particular in an age when this co-operation in many fields is becom-
ing increasingly essential.” (Nuclear Tests (Australia v. France),
Judgment, I.C.J. Reports 1974, p. 268, para. 46.)

103. In its resolution 984 (1995) dated 11 April 1995, the Security
Council took care to reaffirm “the need for all States Parties to the
Treaty on the Non-Proliferation of Nuclear Weapons to comply fully
with all their obligations” and urged

“all States, as provided for in Article VI of the Treaty on the Non-
Proliferation of Nuclear Weapons, to pursue negotiations in good
faith on effective measures relating to nuclear disarmament and on a
treaty on general and complete disarmament under strict and effec-
tive international control which remains a universal goal”.

The importance of fulfilling the obligation expressed in Article VI of
the Treaty on the Non-Proliferation of Nuclear Weapons was also
reaffirmed in the final document of the Review and Extension Conference
of the parties to the Treaty on the Non-Proliferation of Nuclear Weapons,
held from 17 April to 12 May 1995.

In the view of the Court, it remains without any doubt an objective of
vital importance to the whole of the international community today.

x * x

104. At the end of the present Opinion, the Court emphasizes that its
reply to the question put to it by the General Assembly rests on the total-
ity of the legal grounds set forth by the Court above (paragraphs 20 to
103), each of which is to be read in the light of the others. Some of these
grounds are not such as to form the object of formal conclusions in the
final paragraph of the Opinion; they nevertheless retain, in the view of
the Court, all their importance.

105. For these reasons,
THE Court,
(1) By thirteen votes to one,

Decides to comply with the request for an advisory opinion;

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

AGAINST: Judge Oda;

43
266

THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

(2) Replies in the following manner to the question put by the General

44

Assembly :
A. Unanimously,

There is in neither customary nor conventional international law
any specific authorization of the threat or use of nuclear weapons;

B. By eleven votes to three,

There is in neither customary nor conventional international law
any comprehensive and universal prohibition of the threat or use
of nuclear weapons as such;

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

AGAINST: Judges Shahabuddeen, Weeramantry, Koroma;

C. Unanimously,

A threat or use of force by means of nuclear weapons that
is contrary to Article 2, paragraph 4, of the United Nations
Charter and that fails to meet all the requirements of Article 51, is
unlawful;

D. Unanimously,

A threat or use of nuclear weapons should also be compatible
with the requirements of the international law applicable in armed
conflict, particularly those of the principles and rules of interna-
tional humanitarian law, as well as with specific obligations under
treaties and other undertakings which expressly deal with nuclear
weapons;

E. By seven votes to seven, by the President’s casting vote,

It follows from the above-mentioned requirements that the threat
or use of nuclear weapons would generally be contrary to the rules
of international law applicable in armed conflict, and in particular
the principles and rules of humanitarian law;

However, in view of the current state of international law, and of
the elements of fact at its disposal, the Court cannot conclude
definitively whether the threat or use of nuclear weapons would be
lawful or unlawful in an extreme circumstance of self-defence, in
which the very survival of a State would be at stake;

IN FAVOUR : President Bedjaoui; Judges Ranjeva, Herczegh, Shi, Fleisch-
hauer, Vereshchetin, Ferrari Bravo;

AGAINST: Vice-President Schwebel; Judges Oda, Guillaume, Sha-
habuddeen, Weeramantry, Koroma, Higgins;
267 THREAT OR USE OF NUCLEAR WEAPONS (ADVISORY OPINION)

F. Unanimously,

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

Done in English and in French, the English text being authoritative, at
the Peace Palace, The Hague, this eighth day of July, one thousand nine
hundred and ninety-six, in two copies, one of which will be placed in the
archives of the Court and the other transmitted to the Secretary-General
of the United Nations.

(Signed) Mohammed BEDJAOUI,
President.

(Signed) Eduardo VALENCIA-OSPINA,
Registrar.

President BEDJAOUI, Judges HERCZEGH, SHI, VERESHCHETIN and FERRARI
BRAVO append declarations to the Advisory Opinion of the Court.

Judges GUILLAUME, RANJEVA AND FLEISCHHAUER append separate
opinions to the Advisory Opinion of the Court.

Vice-President SCHWEBEL, Judges ODA, SHAHABUDDEEN, WEERAMANTRY,
Koroma and Hicains append dissenting opinions to the Advisory Opinion
of the Court.

(Initialled) M.B.
(Initialled) E.V.O.

45