PUBLIC INTERNATIONAL LAW 2025
INTRODUCTION
Overarching questions of the course
This course approaches public international law through these three central questions:
1. Is international law capable of controlling and addressing current geo-political challenges?
2. How do different systems and regimes of international law interact (e.g. human rights,
humanitarian law, environmental law, economic law)?
3. Does the structure of the international legal order facilitate or limit its capacity to respond to
pressing global problems?
Public international law emerged in Europe after the Peace of Westphalia (1648) as a law governing
relations between formally equal, sovereign, and independent States. Although today, international law
reaches far beyond Europe and increasingly affects individuals, organizations, and other entities,
States remain the primary actors in internal law, thus making them primary bearers of “plenary”
competence in external relations and enjoy presumptive freedom in both their internal and international
relations.
Statehood functions as a kind of “standing” on the international plane, rather than a fixed package of
substantive rights. In legal terms, States are characterized by:
i) full competence to act internationally
ii) prima facie (presumption) exclusive competence over internal affairs
iii) non-subjection to compulsory international jurisdiction without consent
iv) sovereign equality
v) a presumption against derogations from these principles ( the lotus presumption ).
The lotus presumption:
Comes form the S.S. Lotus case ( France v
Turkey, PCIJ, 1927 ).
The Permanent Court of International Justice held:
“States are free to act unless there is a specific
rule of international law that prohibits their
conduct.”
Meaning that restrictions upon the independence
of States cannot be presumed, therefore a State
may do anything unless there is a rule that forbids
it ( Treaties, customs, etc.)
These functional attributes are grounded by the Montevideo criteria of effective statehood:
i) A defined territory
ii) A permanent population
iii) An effective government
iv) And independence, often expressed as the capacity to enter into relations with other States.
,Traditionally, only States counted as “full subjects of international law”, which can be understood as the
only entities that are capable of holding international rights and duties. However, international legal
personalities have expanded. International organizations created by States to pursue common
purposes, are now widely accepted as subjects of international law with a limited functionality, but a
genuine international legal personality.
The most significant development has been the recognition of the individual as a (partial) subject of
international law. Human rights treaties confer directly enforceable rights, while international criminal
law imposes duties and individual criminal responsibility for core international crimes.
Corporations and NGOs, especially in fields such as investment arbitration or consultative status at
the UN, likewise enjoy a limited, functional international status. Modern doctrine therefore distinguishes
between full and partial, objective and relative, original and derived international legal personality,
reflecting a more diverse set of actors while preserving the central role of States in the international
legal order.
WEEK 1 - NUCLEAR WEAPONS
This week’s questions:
1. How are geopolitical relationships determinative of international legal commitments?
2. Why do states have so much control over the system?
3. Why would a state hesitate to sign a treaty controlling their use of such weapons?
How international law is made (treaties & positivism):
States are primary lawmakers. In a positivist view, binding rules come from state consent (treaties and
customs), not morality or religion.
Sources of international law:
1. Treaties (international conventions)
2. Customary international law (general practice accepted as law)
3. General principles of law
4. Judicial decisions & doctrine (subsidiary means)
Treaties & Vienna Convention on the Law of Treaties basics (VCLT):
● Treaty definition ( Art. 2(1)(a) VCLT): written agreement between states, governed by
international law (convention, pact, charter, etc).
● Pacta sunt servanda (art. 26 VCLT): every treaty in force is binding on the parties and must
be performed in good faith.
● Key issues:
1. Conclusion and consent (art. 6-18 VCLT): who can bind the states, signature vs
ratification.
2. Reservations (art. 19-23 VCLT): unilateral statements modifying obligations. “I want to
join X, but don’t agree with A”. E.g. Genocide Convention advisory opinion.
3. Interpretation (art. 31 VCLT): The treaty shall be interpreted according to the ordinary
meaning in context and in light of object and purpose, plus supplementary means (art.
32 VCLT).
4. Termination/validity: Consent, material breach, fundamental change of circumstances (
art. 62 VCLT), impossibility, use of force, jus cogens (art. 53, 64).
Wimbledon principle:
Comes from the S.S. Wimbledon case (PCIJ,
1923).
, When a State accepts obligations by treaty, it is
not “losing” sovereignty, instead, it is using its
sovereignty.
The Court held:
“The right of entering into international
engagements is an attribute of State sovereignty”
Meaning that there is freedom to bind yourself by
law, as treaties are an expression of sovereignty,
not a betrayal of it.
Jus cogens:
The classic definition is found in art. 53 VCLT.
Peremptory norms of general international law (jus
cogens) are fundamental rules accepted by the
international community of states as a whole as
norms from which no derogation is permitted and
which can only be modified by a new norm of the
same character. Any treaty with an existing jus
cogens norm is void, and a later jus cogens norm
terminates incompatible treaties (art. 64).
Examples are genocide, aggression, slavery and
torture.
Core idea:
Super strong rules of international law that
1. No state can validly break, and
2. No treaty or agreement can override.
Global nuclear governance
Risk of a nuclear war is rising again. The war in Ukraine, crises in the Middle East, and rapid nuclear
buildups, especially in East Asia. A new proliferation cascade could see countries like South Korea and
Japan reconsider nuclear weapons as they doubt U.S. guarantees and watch China and North Korea
expand their arsenals.
A) International Atomic Energy Agency (IAEA)
● Created in 1957 to promote safe, secure and peaceful uses of nuclear energy (“atoms
for peace”)
● Implements safeguards in 180+ states to verify that nuclear material is not diverted to
weapons. NNWS under the NPT must conclude comprehensive safeguard agreements
(art. III NPT).
B) Test-ban treaties
● Partial test ban treaty (1963): bans tests in the atmosphere, outer space, and under
water, but not underground (early Cold War step to limit fallout).
● Comprehensive test ban treaty (CTBT, 1996, not in force): Prohibits all nuclear test
explosions but needs specific states to ratify. Key non-ratifyers include the U.S, China,
India, Pakistan.
C) Non-proliferation treaty (NPT,1968/1970)
● Nearly universal (191 parties) and still the core regime
● Grand bargain:
1. Art. I and II
INTRODUCTION
Overarching questions of the course
This course approaches public international law through these three central questions:
1. Is international law capable of controlling and addressing current geo-political challenges?
2. How do different systems and regimes of international law interact (e.g. human rights,
humanitarian law, environmental law, economic law)?
3. Does the structure of the international legal order facilitate or limit its capacity to respond to
pressing global problems?
Public international law emerged in Europe after the Peace of Westphalia (1648) as a law governing
relations between formally equal, sovereign, and independent States. Although today, international law
reaches far beyond Europe and increasingly affects individuals, organizations, and other entities,
States remain the primary actors in internal law, thus making them primary bearers of “plenary”
competence in external relations and enjoy presumptive freedom in both their internal and international
relations.
Statehood functions as a kind of “standing” on the international plane, rather than a fixed package of
substantive rights. In legal terms, States are characterized by:
i) full competence to act internationally
ii) prima facie (presumption) exclusive competence over internal affairs
iii) non-subjection to compulsory international jurisdiction without consent
iv) sovereign equality
v) a presumption against derogations from these principles ( the lotus presumption ).
The lotus presumption:
Comes form the S.S. Lotus case ( France v
Turkey, PCIJ, 1927 ).
The Permanent Court of International Justice held:
“States are free to act unless there is a specific
rule of international law that prohibits their
conduct.”
Meaning that restrictions upon the independence
of States cannot be presumed, therefore a State
may do anything unless there is a rule that forbids
it ( Treaties, customs, etc.)
These functional attributes are grounded by the Montevideo criteria of effective statehood:
i) A defined territory
ii) A permanent population
iii) An effective government
iv) And independence, often expressed as the capacity to enter into relations with other States.
,Traditionally, only States counted as “full subjects of international law”, which can be understood as the
only entities that are capable of holding international rights and duties. However, international legal
personalities have expanded. International organizations created by States to pursue common
purposes, are now widely accepted as subjects of international law with a limited functionality, but a
genuine international legal personality.
The most significant development has been the recognition of the individual as a (partial) subject of
international law. Human rights treaties confer directly enforceable rights, while international criminal
law imposes duties and individual criminal responsibility for core international crimes.
Corporations and NGOs, especially in fields such as investment arbitration or consultative status at
the UN, likewise enjoy a limited, functional international status. Modern doctrine therefore distinguishes
between full and partial, objective and relative, original and derived international legal personality,
reflecting a more diverse set of actors while preserving the central role of States in the international
legal order.
WEEK 1 - NUCLEAR WEAPONS
This week’s questions:
1. How are geopolitical relationships determinative of international legal commitments?
2. Why do states have so much control over the system?
3. Why would a state hesitate to sign a treaty controlling their use of such weapons?
How international law is made (treaties & positivism):
States are primary lawmakers. In a positivist view, binding rules come from state consent (treaties and
customs), not morality or religion.
Sources of international law:
1. Treaties (international conventions)
2. Customary international law (general practice accepted as law)
3. General principles of law
4. Judicial decisions & doctrine (subsidiary means)
Treaties & Vienna Convention on the Law of Treaties basics (VCLT):
● Treaty definition ( Art. 2(1)(a) VCLT): written agreement between states, governed by
international law (convention, pact, charter, etc).
● Pacta sunt servanda (art. 26 VCLT): every treaty in force is binding on the parties and must
be performed in good faith.
● Key issues:
1. Conclusion and consent (art. 6-18 VCLT): who can bind the states, signature vs
ratification.
2. Reservations (art. 19-23 VCLT): unilateral statements modifying obligations. “I want to
join X, but don’t agree with A”. E.g. Genocide Convention advisory opinion.
3. Interpretation (art. 31 VCLT): The treaty shall be interpreted according to the ordinary
meaning in context and in light of object and purpose, plus supplementary means (art.
32 VCLT).
4. Termination/validity: Consent, material breach, fundamental change of circumstances (
art. 62 VCLT), impossibility, use of force, jus cogens (art. 53, 64).
Wimbledon principle:
Comes from the S.S. Wimbledon case (PCIJ,
1923).
, When a State accepts obligations by treaty, it is
not “losing” sovereignty, instead, it is using its
sovereignty.
The Court held:
“The right of entering into international
engagements is an attribute of State sovereignty”
Meaning that there is freedom to bind yourself by
law, as treaties are an expression of sovereignty,
not a betrayal of it.
Jus cogens:
The classic definition is found in art. 53 VCLT.
Peremptory norms of general international law (jus
cogens) are fundamental rules accepted by the
international community of states as a whole as
norms from which no derogation is permitted and
which can only be modified by a new norm of the
same character. Any treaty with an existing jus
cogens norm is void, and a later jus cogens norm
terminates incompatible treaties (art. 64).
Examples are genocide, aggression, slavery and
torture.
Core idea:
Super strong rules of international law that
1. No state can validly break, and
2. No treaty or agreement can override.
Global nuclear governance
Risk of a nuclear war is rising again. The war in Ukraine, crises in the Middle East, and rapid nuclear
buildups, especially in East Asia. A new proliferation cascade could see countries like South Korea and
Japan reconsider nuclear weapons as they doubt U.S. guarantees and watch China and North Korea
expand their arsenals.
A) International Atomic Energy Agency (IAEA)
● Created in 1957 to promote safe, secure and peaceful uses of nuclear energy (“atoms
for peace”)
● Implements safeguards in 180+ states to verify that nuclear material is not diverted to
weapons. NNWS under the NPT must conclude comprehensive safeguard agreements
(art. III NPT).
B) Test-ban treaties
● Partial test ban treaty (1963): bans tests in the atmosphere, outer space, and under
water, but not underground (early Cold War step to limit fallout).
● Comprehensive test ban treaty (CTBT, 1996, not in force): Prohibits all nuclear test
explosions but needs specific states to ratify. Key non-ratifyers include the U.S, China,
India, Pakistan.
C) Non-proliferation treaty (NPT,1968/1970)
● Nearly universal (191 parties) and still the core regime
● Grand bargain:
1. Art. I and II
