Introduction, p. 3ff
What is International Law?
 Classic Divisions
 1) Public International Law (IL):
 Traditional definition of public international law:
“IL concerns the legal relationship between sovereign
states”.
– Historically, the only relevant actors were states.
– After WWII, human rights field added the individual, and
certain groups, to the actors in IL. Then multinational
corporations, non-state actors, such as paramilitary
groups.
– the subject matter covered by IL also expanded
dramatically.
Classic Divisions continued
 2) Private International Law: legal relationships occurring in
international business transactions and the legal regime that governs
them:
 e.g., WTO (World trade Organization), TRIPS (Trade Related
Intellectual Property), intellectual property treaty rights, international
trade, transnational commercial contracts, transnational taxation etc.
 this course focuses on public IL, although much of what you learn here
will be applicable and useful in private international law courses, e.g.,
the law of treaties, international jurisdiction, how international courts
work, etc.
So…What is International Law?
 First, what is law?
 If you landed in a new country and wanted
to know if it had a legal system, what sort of
structures would you look for to answer that
question?
How Is IL Made and Who Makes It?
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Is there an international legislature?
Is there an international executive?
Is there an international judiciary?
If not, or if only in a rudimentary sense, how
does IL get made? Can it really be said to
be a system of law or is it just a set of
hopeful prescriptions?
 What are the sources of IL. See ICJ Statute.
Sources of IL, p. 5ff
Custom
 1) Custom
 What is custom? “A consistent practice of states
engaged in by them out of a sense of legal
obligation.”
 How consistent does the practice have to be?
 What sort of practices? What is a sense of legal
obligation?
 Does custom bind even those states that disagree
with the custom?
 What is opinio juris?
 What is a jus cogens custom?
Article 38 Statute of the ICJ
 Statute of the International Court of Justice (ICJ)
(www.icj-cij.org)
 sources of law that may be applied by the ICJ (Art.
38):
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International conventions,
international custom,
general principles of law,
judicial decisions (but see art. 59 of ICJ’s Statute, Doc. Supp. p. 35)
teachings of international law scholars as a subsidiary means for
determining the rules of law.
The Paquete Habana,
U.S. Supreme Court 1900
 What was the custom found by the S.Ct. in The Paquete
Habana? (US court decision, but typical of the way
national courts go about finding international custom).
 How did the court go about finding the custom?
 What persuaded the court that the custom was binding?
 Why are US courts obliged to follow international custom?
 Would the court have followed the custom if Congress had
passed a law stating that no vessels were exempt from
capture as prize of war?
 If there is an internationally binding custom, are states free
to pass contrary legislation?
 If they are, won’t that mean that states are only bound by
custom if they want to be so bound?
The Relationship of IL to
Domestic (National) Law
 Common law and civil law countries usually
incorporate IL into domestic law provided it does
not conflict with existing national law. A few states
make IL supersede national law.
 All states enter into agreements with other states
(treaties). Some nations require legislation before
the treaty will become operative as law but others
make treaties operative as soon as the required
national and international procedures are
completed.
The Relationship of IL to
Domestic Law (continued)
 Can subsequent legislation override existing
treaties? The answer in the US, and a number of
other countries, is “Yes” but other countries make
treaties supreme over regular legislation.
 Note: At the international level, a state may not
rely upon its internal legislation to excuse nonperformance of an international obligation. (Vienna
Convention on the Law of Treaties, arts. 27 & 46,
Doc. Supp. p.110 & 115).
Abdullahi v. Pfizer, Inc
U.S. Ct of Appeals 2009
 What was the binding international law custom
found in the Abdullahi Case?
 What sources of law did the majority opinion rely
upon?
 Is the US a party to the ICCPR? www.un.org If
so, why didn’t the plaintiff’s lawyers rely on that
treaty to clinch the case?
 Why did the dissenting judge disagree with the
majority?
 If Nigerian governmental officials had agreed to go
ahead with the treatments without patient or
parental consent, thus probably barring actions in
Nigerian courts, should Nigerians be able to sue in
US courts?
Regional Custom
 In the Asylum Case (Colombia v. Peru)
1950 I.C.J. 266, the ICJ accepted the idea
of regional custom, that is a custom not
found among nations generally, but found in
a particular region of the world. Colombia
had invoked Latin American regional
custom. The ICJ, however, found that
Colombia had failed to prove the regional
custom because there was a lack of uniform
practice accepted as law.
Special or Local Custom
 In the Right of Passage Case (Portugal v.
India) 1960 I.C.J. 6, the ICJ agreed that
custom could arise between two (or a limited
number of) states where there had been a
long practice accepted as law. Portugal
argued that two local customs had arisen
and were binding on India. The ICJ agreed
with Portugal with respect to one of the local
customs but not with respect to the other.
Jus Cogens
 States are usually free to disregard international custom by
passing contrary laws, with the result that they will not be
bound by the custom. There are some customs, however,
which states are not free to reject. These customs are
considered to be fundamental law or “jus cogens”. How do
customs become jus cogens?
 There is disagreement on which rules fit this category but,
for example, many agree that the following prohibitions
would meet the requirements: torture, racial discrimination,
genocide, war crimes, crimes against humanity, slavery
and piracy. Which other rules should be in this category?
Treaties as a Source of IL
 Treaties, of course, bind the parties.
 Can treaties bind non-parties? By what
method?
 How can treaties provide a general source
of IL?
North Sea Continental Shelf Cases
(FRG v. Denmark and Netherlands)
1969 I.C.J. 3
www.worldatlas.com/aatlas/infopage/northsea.gif
What does art. 6(2) of the 1958 Geneva Convention on the
Continental Shelf state? Why did Denmark and the
Netherlands think that art. 6(2) applied to FRG even
though FRG was not a party to the treaty?
 What is a reservation to a treaty?
Why did the Court not accept the argument that the
equidistant principle had become a rule of customary law?
 How much state practice would satisfy the Court that a
practice had become customary law?
 What sort of evidence would you present to the Court to
demonstrate opinio juris?
General Principles of Law as a
Source of IL
 What are general principles of law?
 Examples?
 Which general principles of law were applied
in the Chorzow Factory Case?
Judicial Decisions as a Subsidiary
Source of IL
 Why do judicial decisions only serve as a
subsidiary source of IL law?
 Exactly how are judicial decisions used by
International Courts as a source of IL law?
 What does article 59 of the ICJ Statute
say? What does it mean?
Writings by Scholars of IL as a
Source of IL
 Why does there seem to be reluctance by
international judges to refer to scholars’
work to support their conclusions of law?
 Other sources might be found in UN
General Assembly Resolutions provided
they express custom.