International law II
2021-2022
Course material:
Syllabus international law II, Cedric van Assche, third ed 2021
Source book: international law documents, blackstones statutes 15th ed.
Course content
1. Introduction: Methodology international law
2. Law of friendly relations
a. General principles (territorial sovereignty, threat of use of force, peaceful settlement of
disputes, principle of non-intervention, sovereign equality, respect for HR, etc.)
3. Treatment of foreigners in IL
a. Investments law
4. Treaty law
5. State responsibility
a. Primary rules: Law of Friendly Relations, Treatment of foreigners
b. Secondary rules: Treaty law
c. Environmental law
6. Sanctions
Glossary
Art= article
Arts= articles
R = right
S = state
Ss = states
T = treaty
Ts = treaties
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,Methodology international law
General characteristics national law v. international law
National law
• Unicity of national legal norms: we have 1 Belgian/French/Italian law. The national laws are
unique.
• Furthermore, there is also a unicity of the national power, there is one government, one parliament
etc in each country.
• National law is a law of subordination; the national parliament and government will impose their
law on their subjects, whether or not the subjects agree.
→ National law is characterized by unicity and subordination of its norms.
International law
• Principle of relativity of IL: On the contrary to national law, IL does not contain a unique set of
norms that are valid for all states. It exists of a plurality of international, multilateral legal norms
applicable to some states.
Bvb the European States must follow the norms of the EU, but other S must not per se follow them.
Each S will be bound a set of IL but which one might differ from S to S.
Although some IL norms are universal (IGR), some T are ratified by all S. Bvb Charter of the UN.
• Plurality of the powers: in IL you have almost 200 equally sovereign S, +- 600 IO and several
international legal bodies (ICJ, Perm Court of Arbitration, Int Court of the Sea). There is no Int
court that has jurisdiction over all S. Bvb: Even the Security Council of the UN has very limited
competences to restore and maintain peace (because of the veto R of the perm 5).
• Decentral creation, observation, application, and enforcement of IL: The creation, observation and
application of IL will occur mainly by the S themselves. The same is true for the enforcement of IL
and sanctions. You have collective sanctions (bvb ordered by the UN) but they are rather the
exception.
• !! IL is a law of juxtaposition/coexistence: IL is based on the agreement of the S, due to the principle
of the equality of sovereign S = one S cannot impose its will on another S → S have to agree before
a norm can bind them. The agreement = the legal base of the int norm. S are the producers, the
subjects, and the objects of the IL.
The acceptance will also constitute the legal base for the juri of international courts. Once again,
the agreement is needed because of the principle of equal sovereignty of S. Bvb: one S cannot sue
another before the ICJ without the latter having recognized the juri of the ICJ.
Although IL is a law of juxtaposition, you have some supranational org → where you will find
some elements of subordination; the supranational IO can bind its members. Bvb: If the EU adopts
binding decisions, this will bind the EU S.
→ The norms of IL are plural, juxtaposed and based on agreement of equally sovereign S.
Sources of IL (6)
1. Treaties
= international agreement concluded between S or IO, in written form and governed by IL.
2. Customary International Law (CIL), most ancient form of IL.
Important doc: see conclusions of ILC (part of the UN Assembly) on the identification of CIL:
https://legal.un.org/ilc/texts/instruments/english/commentaries/1_13_2018.pdf
The prof says to read the conclusions 2-6 of the beforementioned document.
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, CIL most reunite 2 elements:
• Objective element: state practice or “usus” (legislative, executive, judicial, admin,
diplomatic, etc.). It must be uniform and constant.
• Subjective element: conviction of the existence of an int obligation or “opinio juris”
Bvb: foreign heads of S will be inviolable abroad. The foreign heads of S cannot be arrested or
detained abroad. If Macron was to come to Brussels, it will not be possible to arrest him. This
principle is respected by all S (you have usus) and because you have usus, this means that S also
have the opinio juris that this rule is a universal rule of IL.
Exception for CIL: persistent objector. When a S has objected to a rule of CIL, when that rule was
in the process of becoming CIL, this rule will not be opposable to the objecting S. The S cannot
prevent the formation of a new rule of CIL BUT it would mean that the new rule is not opposable
to this S.
3. General principles of law
= principles of domestic law that are common to various national legal systems and those
principles must be transposable to the int legal order. This is an autonomous source in the IL.
Why are those principles important? Their main function is to fill gaps. But this function is limited,
it’s not that important.
Bvb: principle of prohibition of the abuse of law, la théorie des droits acquis, principle of res judicata
(a judgement of a court will be binding for the parties), principle that no judge may be judged in its
own court, principle relating to the burden of proof (the one claiming something must be the one
bringing the proof), etc.
General principles of law =/= general principles of IL!! The first one is an autonomous source of
IL and the latter is not. The latter are general fundamental principles of the int order that could be
derived from T or CIL, so this is not an autonomous source. Bvb: prohibition of the use of force;
this is both a rule of IL (art 2(4)) UN Charter) and a general principle of IL. Principle of non-
intervention, of good faith, etc. ~ All the principles of the Law of Friendly Relations.
4. Unilateral acts of States
Bvb: the nuclear test cases admitted that S could engage themselves legally and unilaterally. In the
case (ICJ; N-Zealand v France and Aus v France) France conducted nuclear tests in the
atmosphere of the Pacific Ocean. N-Z and Aus were not happy for the nuclear dust fallout on their
territories and sued FR before the ICJ. ICJ admitted that FR could unilaterally bind itself to do
something. France put a moratorium on the nuclear testing via declarations → this decla will bind
FR. A declaration is only binding if it’s clear that the S meant to be bound by it (legal intention). It
must be a specific and clear declaration regarding a specific topic, not a general declaration.
5. Decisions of IO
Emphasis on term “decisions”, normally IO make “resolutions” which can be binding or not BUT
if it’s binding, then they are called “decisions”. Non-binding resolutions are called
“recommendations”. To know if something’s binding or not you have to look at the constituent
element, via which mean was the resolution taken?
Bvb EU treaties: a directive is binding, UN Charter: the resolutions of the SC taken in chapter 7 can
be binding.
You also have the important distinction between the words “should” → non-binding, and “shall”
→ binding.
6. Solo consensu agreements
Those are informal legal binding agreements. Bvb: oral legal binding agreements, agreement
concerning the provisional application of a T → this is based on the solo consensu agreement of
the parties.
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,Subsidiary means for the determination of norms of IL (3)
1. Case law (international or national (highest national courts)
In itself it’s not a source of IL. A judge may not create a new rule of IL and apply it. It is a subsidiary
mean for the determination for norms of IL, especially for CIL. See conclusion 13 of the document
of the ILC: “Conclusion 13: 1. Decisions of international courts and tribunals, in particular of the
International Court of Justice, concerning the existence and content of rules of customary
international law are a subsidiary means for the determination of such rules.
Commentary: Draft conclusion 13 concerns the role of decisions of courts and tribunals, both
international and national, as an aid in the identification of rules of customary international law. It
should be recalled that decisions of national courts may serve a dual role in the identification of
customary international law. On the one hand, as the above draft conclusions 6 and 10 indicate,
they may serve as practice as well as evidence of acceptance as law (opinio juris) of the forum
State. Draft conclusion 13, on the other hand, indicates that such decisions may also serve as a
subsidiary means (moyen auxiliaire) for the determination of rules of customary international law
when they themselves examine the existence and content of such rules. (2) Draft conclusion 13
follows closely the language of Article 38, paragraph 1 (d), of the Statute of the International Court
of Justice, according to which, while decisions of the Court have no binding force except between
the parties, judicial decisions are a subsidiary means for the determination of rules of international
law, including rules of customary international law. The term “subsidiary means” denotes the
ancillary role of such decisions in elucidating the law, rather than being themselves a source of
international law (as are treaties, customary international law and general principles of law). The
use of the term “subsidiary means” does not, and is not intended to, suggest that such decisions
are not important for the identification of customary international law.
2. Doctrine
It is what’s learned at school, what the experts, professors teach to the students. It is a statement
of already existing law. It’s once again a subsidiary mean for the determination of CIL, what’s taught
at school is considered opinion juris.
Furthermore, doctrine will explain, comment, criticize rules of IL and propose adjustments to the
current state of norms of IL. See conclusion 14 of draft version ILC.
3. Declarations of IO or intergov conferences
Declarations are a specific kind of resolutions, ones that are non-binding BUT they may contain
existing obligations of IL. See conclusion 12 of ILC document: “1. A resolution adopted by an
international organization or at an intergovernmental conference cannot, of itself, create a rule of
customary international law. 2. A resolution adopted by an international organization or at an
intergovernmental conference may provide evidence for determining the existence and content of
a rule of customary international law or contribute to its development. 3. A provision in a resolution
adopted by an international organization or at an intergovernmental conference may reflect a rule
of customary international law if it is established that the provision corresponds to a general
practice that is accepted as law (opinio juris)” It may contain CIL if usus and opinion juris is met.
Bvb: The Friendly Relations Declaration adopted contains a lot of CIL principles; principle of good
faith, non-intervention principle, etc.
Other sources:
Equity
= the idea of justice or fairness. It is not an IL nor a subsidiary mean for the determination thereof BUT it
could be that a norm of IL may contain an element of “equity”.
Bvb: In HR law, you have a right to a fair trial. “Fair” is a reference to equity. This HR law can be found in
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,T. Bvb2: In the law of the sea the maritime delimitation of Continental Shelf and EEZ must be achieved in
an equitable solution. Also, international watercourses must be used in an equitable and reasonable way.
Soft law
This is a law in the way of being delivered, it could be that one day this normative proposal becomes
binding.
Soft law does not have any legally binding powers. They are for ex recommendations, code of conducts,
etc.
Gentlemen’s agreement or memorandum of understanding (MOU)
= political agreements, which do not have legally binding force. Difference with soft law? SL is something
of a legal nature whereas a MOU is something entirely political.
Bvb: a Belgian minister of foreign affairs may agree on something with the minister from France and create
a written MOU. Most of the time a MOU will be executed even though it’s not binding because otherwise
the Belgian minister would lose all its credibility. BUT a gentlemen’s agreement does not create obligations
or norms. If one S does not follow the agreement, nothing can be done about this because it is not
something of legal order, merely political.
Principle of equivalence of sources
There is no de jure hierarchy between the sources, one is not higher than the other. BUT in practice there
is a (de facto) hierarchy based on the principle of lex specialis derogate legi generali → as regard the
applicable source of law one will often have recourse to 1) T, 2) CIL and then 3) General principles of law
(there main function is to fill gaps).
The second comment that must be made is that you have the principle of compliance of resolutions of IO.
In the law of IO, you have a legal order of the IO is like a national legal order. At the top you have the
constituent instruments (T creating the IO). The T will set out the main functions of the IO but will also
create the organs of the IO. Those organs will adopt resolutions: recommendations or decisions. Principle
of compliance with the constitutive instrument of that organization. Bvb: EU members must respect the
EU treaties and the respect will be enforced (Eu HvJ).
You need to make a distinction between the source of law and the legal norm. It could be that one same
rule may find its existence in various sources. Bvb: the rule pacta sunt servanda (agreements must be kept",
is a brocard (elementary principle) and a fundamental principle of law). This rule can be found in different
legal documents.
Principle of separate applicability of norms
The ICJ in the Nicaragua case made ref to this principle, a norm of CIL will have a separate applicability
than the same norm you find in a treaty. So, 2 rules of the same content can have 2 separate applicability.
Why? For example, if you find the rule in a T of an organization and in CIL if one S is not a party of this T,
the rule in the T does not apply to him → only the one in the CIL.
No equivalence of the norms
There is no principle of equivalence of norms equivalence of the sources of IL. The norms have no
equivalence, some norms take a higher rank than others. There are two cat of norms that have a higher
hierarchy.
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,Ius cogens
The ius cogens, these are imperative norms, where no derogation is possible. The opposite of ius cogens
= ius dispositivum; laws which a state may derogate from. Bvb if S sign a T to protect fauna and flora, those
S may change the T, may end the T, etc. Ius cogens supposes the existence of a public int legal order. The
prohibition of slavery, aggression, apartheid, genocide are examples of ius cogens. No S is today allowed
to make a T for slave commerce. If this is done, the T will be immediately invalid. Norms against ius cogens
are in nature not valid. Therefor ius cogens norms have a higher norm.
!! Ius cogens is not a source of IL, it’s a characteristic of a norm.
Art 53 Vienna Convention 1969: “A treaty is void if, at the time of its conclusion, it conflicts with a
peremptory norm of general international law. For the purposes of the present Convention, a peremptory
norm of general international law is a norm accepted and recognized by the international community of
States as a whole as a norm from which no derogation is permitted and which can be modified only by a
subsequent norm of general international law having the same character”
UN obligations
Art 103 UN Charter: In the event of a conflict between the obligations of the Members of the United Nations
under the present Charter (and adopted in the SC) and their obligations under any other international
agreement (and also CIL), their obligations under the present Charter shall prevail. You see that UN
obligations have prevalence over other obligations.
The sanction here for the rules going against a UN obli, is not the invalidity of the rule (such as for ius
cogens) but the inapplicability (most of the time temporary).
What is the ratio legis of art 103? The idea after WO II was to create an IO where an organ, the SC, would
be responsible for the collective security (maintain and restore peace and security). The SC was given the
possibility to impose sanctions. Often, those sanctions (economic, embargoes, political, etc.) go against
provisions in T, for example trade T. In case of a conflict, the decisions of the UN will prevail.
Principle of relativity of international law
Except the case of ius cogens (and even there, the S have to recognize and accept ius cogens), you have
the principle of relativity of international law → Ex consensu advenit vinculum (from the consent comes
the obligation), S cannot be bound to IL without their consent. Why? Principle of sovereignty of S.
Gevolgen?
→ T will only bind the members of the T. EU regulations will not bind non-EU-members.
This also explains why S can act as persistent objectors.
Legal base binding IL
The legal base for int norms is the agreement (formal/informal) → all int norms therefore constitute an
agreement, also decisions of IO (because they are taken with the consent of the members). This is also the
case for CIL, for there to be CIL, you must have opinion juris and usus → this can only happen if S behave
themselves in a way that shows that they agree with the norm.
Principle of good faith
This applies to all international obligations, their source irrelevant, and will apply on the fulfilment and
interpretation of the obligations in good faith. More on this later.
Importance of legal reasoning
Lawyers often use syllogism (a form of reasoning in which a conclusion is drawn from two given or assumed
propositions (premises); a common or middle term is present in the two premises but not in the conclusion,
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, which may be invalid (all dogs are animals; all animals have four legs; therefore, all dogs have four legs ).
There are 2 methods of reasoning that exist: deduction (you start from a rule and apply this) v inductive
method (you start from a particularity and turn this into a rule, see how CIL is created).
Law of Friendly Relations
Classical IL (until WO I) was based on:
• Freedom
• Sovereignty
• Force
• Effectiveness
Disputes were solved using armed force between S. This classical law has been modified due to various
factors: Russian revo (1917) and the decolonization process (first Lat-AM, Asia, and later Africa).
Those new independent nations had another view on IL → IL underwent a revision → a compromise was
found between liberal-socialist vision and the one of the new nations → the new IL was called the “law of
friendly relations” (LFR).
Important to the LFR was the fundamental rights and duties of all nations. The principles of LFR are general
or universal, binding all S. Those principles can today be found in Ts, such as the UN Charter.
BUT a compromise was not always possible, leaving place for some contradictions in the LFR. They will
be brought up later.
The fundamental principles of LFR
• Territorial sovereignty diligence
o Right: Exclusive territorial • Prohibition of the threat/use of force
jurisdiction o Peaceful settlement of int disputes
o Duty: Principle of due care/due • Sovereign equality of states
• Non-intervention • Cooperation
• Self-determination of people • Good faith
• Respect for HR
On the syllabus p12/13 you will see complementary sources (!!) such as the UN Charter, IL case law &
resolution 2625 (1970) “Declaration on principles of IL concerning FR and cooperation among S in
accordance with the UN Charter”. The last one was adopted without votes, meaning by consensus (so no
objections) =/= unanimity.
The 2625 reso reflect CIL. This document will be studied thoroughly, READ IT!
All principles mentioned in the docs above are interrelated, one principle cannot be understood without
regard for the other sources.
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