| I. | Substantive International Law - First Part |
| 2. | SOURCES OF INTERNATIONAL LAW |
| 2.2. | Customary International Law |
| 2.2.2. | Evidence of Customary International Law |
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Military and Paramilitary Activities
(Nicaragua/United States of America)
Merits. J. 27.6.1986
I.C.J. Reports 1986, p. 14
[p. 97] In this respect the Court must not lose sight of the Charter
of the United Nations and that of the Organization of American States,
notwithstanding the operation of the multilateral treaty reservation. Although
the Court has no jurisdiction to determine whether the conduct of the United
States constitutes a breach of those conventions, it can and must take them into
account in ascertaining the content of the customary international law which the
United States is also alleged to have infringed.
[pp. 104-105] The question remains whether the lawfulness of the use
of collective self-defence by the third State for the benefit of the attacked
State also depends on a request addressed by that State to the third State. A
provision of the Charter of the Organization of American States is here in point
: and while the Court has no jurisdiction to consider that instrument as
applicable to the dispute, it may examine it to ascertain what light it throws
on the content of customary international law. The Court notes that the
Organization of American States Charter includes, in Article 3 (f), the
principle that: "an act of aggression against one American State is an act
of aggression against all the other American States" and a provision in
Article 27 that:
"Every act of aggression by a State against the territorial integrity
or the inviolability of the territory or against the sovereignty or political
independence of an American State shall be considered an act of aggression
against the other American States."
Furthermore, by Article 3, paragraph 1, of the Inter-American Treaty of
Reciprocal Assistance, signed at Rio de Janeiro on 2 September 1947, the
High-Contracting Parties
"agree that an armed attack by any State against an American State
shall be considered as an attack against all the American States and,
consequently, each one of the said Contracting Parties undertakes to assist in
meeting the attack in the exercise of the inherent right of individual or
collective self-defence recognized by Article 51 of the charter of the United
Nations";
and under paragraph 2 of that Article,
"On the request of the State or States directly attacked and until the
decision of the Organ of Consultation of the Inter-American System, each one of
the Contracting Parties may determine the immediate measures which it may
individually take in ful filment of the obligation contained in the preceding paragraph and in
accordance with the principle of continental solidarity."
(The 1947 Rio Treaty was modified by the 1975 Protocol of San José,
Costa Rica, but that Protocol is not yet in force.)
The Court observes that the Treaty of Rio de Janeiro provides that measures
of collective self-defence taken by each State are decided "on the request
of the State or States directly attacked". It is significant that this
requirement of a request on the part of the attacked State appears in the treaty
particularly devoted to these matters of mutual assistance; it is not found in
the more general text (the Charter of the Organization of American States), but
Article 28 of that Charter provides for the application of the measures and
procedures laid down in "the special treaties on the subject".
At all events, the Court finds that in customary international law, whether
of a general kind or that particular to the inter-American legal system, there
is no rule permitting the exercise of collective self-defence in the absence of
a request by the State which regards itself as the victim of an armed attack.
The Court concludes that the requirement of a request by the State which is the
victim of the alleged attack is additional to the requirement that such a State
should have declared itself to have been attacked.
At this point, the Court may consider whether in customary international law
there is any requirement corresponding to that found in the treaty law of the
United Nations Charter, by which the State claiming to use the right of
individual or collective self-defence must report to an international body,
empowered to determine the conformity with international law of the measures
which the State is seeking to justify on that basis. Thus Article 51 of the
United Nations Charter requires that measures taken by States in exercise of
this right of self-defence must be "immediately reported" to the
Security Council. As the Court has observed above, a principle enshrined in a
treaty, if reflected in customary international law, may well be so unencumbered
with the conditions and modalities surrounding it in the treaty. Whatever
influence the Charter may have had on customary international law in these
matters, it is clear that in customary international law it is not a condition
of the lawfulness of the use of force in self-defence that a procedure so
closely dependent on the content of a treaty commitment and of the institutions
established by it, should have been followed. On the other hand, if self-defence
is advanced as a justification for measures which would otherwise be in breach
both of the principle of customary international law and of that contained in
the Charter, it is to be expected that the conditions of the Charter should be
respected. Thus for the purpose of enquiry into the customary law position, the
absence of a report may be one of the factors indicating whether the State in
question was itself convinced that it was acting in self-defence.
[p. 305 D.O. Schwebel] Nor can it be persuasively argued
that the sweeping provisions of the OAS Charter concerning intervention
constitute customary and general international law. There is no universal treaty
which has incorporated those provisions into the body of general international
law. There is hardly sign of custom - of the practice of States - which
suggests, still less demonstrates, a practice accepted as law which equates with
the standards of non-intervention prescribed by the OAS Charter. State practice
in the Americas - by States of Latin America as by others - does not begin to
form a customary rule of non-intervention which is as categoric and
comprehensive as are the provisions of the OAS Charter. Thus it may be contended
that, in this case, the Court can apply such customary international law of
non-intervention as there is, a customary international law which is much
narrower than that which the OAS Charter enacts for the parties to it.
