Law of Treaties Public International Law
PROBLEM 2
Learning objectives:
1. What is a treaty and are treaties binding upon the parties?
2. How must a treaty be interpreted?
Literature:
- Jan Klabbers, ‘International Law’, Chapter 3
- UN Treaty Handbook 12-19, accessible via E-lesson 22
- E-lesson 22
- Legislation: VCLT
- Gabcikovo-Nagymaros-case
- La Grand-case
- Tyer v. UK-case
1 WHAT IS A TREATY AND ARE TREATIES BINDING UPON THE PARTIES?
Introduction
Law of treaties is governed by 2 separate mechanisms:
1. The Vienna Convention on the Law of Treaties (VCLT)
2. Customary international law
VCLT is mostly a codification of customary international law, so these sources of law overlap to a large
degree.
In fact, treaties form a crucial basis of relations between states and also form the legal basis of
international organizations (which are created on the bases of a founding treaty, entered into by the
organization’s member states).
Moreover, many international legal disputes arise out of the interpretation, application or termination of
treaties.
9 Good example of such a dispute is the Gabcikovo-Nagymaros-case, which involved a bilateral
treaty between Hungary and Czechoslovakia.
VCLT
- Progressive document
- Scope of it is limited
o Solely applicable to treaties between states (art. 1 VCLT)
§ It does not contain provisions that are applicable to treaties concluded
between states and international organizations, or to treaties concluded
between international organizations
o Does not contain any provisions on state succession to treaties (that is, when a new
successor state forms and replaces a predecessor state)
o Treaties may be affected by various factors, such as situations of armed conflict, but
the VCLT is silent on such effects.
Two types of treaties: Art. 2(1) VCLT
1. Bilateral “Treaty” means an international agreement
o International agreement between two concluded between states in written form and
contracting parties (states) governed by international law, whether embodied in
a single instrument or in two or more related
2. Multilateral
instruments and whatever its particular designation.
o Agreements involving more than two parties
1
, Law of Treaties Public International Law
The definition of ‘treaty’ in art. 2(1)(a) VCLT has several implications for the scope of applicability of the
VCLT:
1. VCLT only applies to treaties between states
2. VCLT only applies to written agreements (although, according to art. 3 VCLT, this rule does not
affect the applicability of other agreements)
3. Agreements between states which are governed by specific domestic/municipal law are
excluded from the scope of the VCLT.
International law does not require a particular form for a document to be classified as a treaty, as long
as the parties have intended to create (international) legal obligations. The intention of creating legal
obligations signifies the crucial distinction between formal international instruments (treaties) and
informal international instruments (such as ‘memoranda of understanding’)
- Memorandum of understanding = an agreement between two or more parties outlined in a
formal document. It is not legally binding but signals the willingness of the parties to move
forward with a contract.
Two basic principles:
1. Treaties need to be based on the free consent of states → corollary to the concept of state
sovereignty
2. The freedom of states is not unlimited → once consent to be bound has been expressed and
the treaty has entered into force, the treaty shall be kept by the parties in good faith (pacta
sunt servanda, art. 26 VCLT)
o Even contrary domestic law is not a valid excuse for failing to perform a treaty
obligation (art. 27 VCLT)
The principle of good faith/pacta sunt servanda
One of the most fundamental principles of the law of treaties is that obligations under a treaty should
be performed ‘in good faith’→ principle of pacta sunt servanda
- Underlying reason: states possess full sovereignty and are in no way obligated to enter into
treaty obligations with each other. The fact that states enter into treaty relations out of their free
will indicates that they will perform their treaty obligations in good faith
Codified in art. 26 VCLT: “Every treaty in force is binding upon the parties to it and must be performed
by them in good faith”
- Two main elements:
o The treaty in force is binding upon the parties
o The treaty must be performed by the parties in good faith
- Importance pacta sunt servanda confirmed in Gabcikovo-Nagymaros-case:
Facts:
In 1977, Hungary and Czechoslovakia adopted a treaty on “the construction and operation of the
Gabcikovo-Nagymaros System of Locks”. Both parties would commence building locks in Gabcikovo and
in Nagymaros, each party responsible for the construction of the locks in their own territory. However, the
Hungarian government decides to suspend the construction. Czechoslovakia was independently exploring
other possible ways to continue the operation by itself. One solution found was known as ‘Variant C’. In
1992, Hungary informed Czechoslovakia about its unilateral termination of the Treaty. Czechoslovakia
continued operations on ‘Variant C’. To Hungary, ‘Variant C’ violated its sovereignty and territorial integrity.
According to Slovakia, the continuance of ‘Variant C’ was a lawful countermeasure against Hungary’s
illegal act of suspending and abandoning its works on the Nagymaros-project and the Gabcikovo parts of
the projects for which it was responsible under the Treaty.
Legal question(s)
- Was Hungary allowed to suspend and, later on, abandon its works on the Nagymaros project on
the Gabcikovo parts of the projects for which it was responsible under the Treaty?
- Were the Czech and Slovak Republic entitled to continue the unilateral operations on the
Danube?
- And what are the legal effects on the unilateral termination by Hungary of the Treaty in 1992?
- What are the legal consequences of the aforementioned questions?
When Hungary argued that a fundamental change in environmental awareness, in conjunction with the
fall of communism, ought to release it from a treaty with Slovakia to build a possibly harmful dam in the
Danube river, the Court suggested that the changes had not been entirely unforeseeable and did not
2
PROBLEM 2
Learning objectives:
1. What is a treaty and are treaties binding upon the parties?
2. How must a treaty be interpreted?
Literature:
- Jan Klabbers, ‘International Law’, Chapter 3
- UN Treaty Handbook 12-19, accessible via E-lesson 22
- E-lesson 22
- Legislation: VCLT
- Gabcikovo-Nagymaros-case
- La Grand-case
- Tyer v. UK-case
1 WHAT IS A TREATY AND ARE TREATIES BINDING UPON THE PARTIES?
Introduction
Law of treaties is governed by 2 separate mechanisms:
1. The Vienna Convention on the Law of Treaties (VCLT)
2. Customary international law
VCLT is mostly a codification of customary international law, so these sources of law overlap to a large
degree.
In fact, treaties form a crucial basis of relations between states and also form the legal basis of
international organizations (which are created on the bases of a founding treaty, entered into by the
organization’s member states).
Moreover, many international legal disputes arise out of the interpretation, application or termination of
treaties.
9 Good example of such a dispute is the Gabcikovo-Nagymaros-case, which involved a bilateral
treaty between Hungary and Czechoslovakia.
VCLT
- Progressive document
- Scope of it is limited
o Solely applicable to treaties between states (art. 1 VCLT)
§ It does not contain provisions that are applicable to treaties concluded
between states and international organizations, or to treaties concluded
between international organizations
o Does not contain any provisions on state succession to treaties (that is, when a new
successor state forms and replaces a predecessor state)
o Treaties may be affected by various factors, such as situations of armed conflict, but
the VCLT is silent on such effects.
Two types of treaties: Art. 2(1) VCLT
1. Bilateral “Treaty” means an international agreement
o International agreement between two concluded between states in written form and
contracting parties (states) governed by international law, whether embodied in
a single instrument or in two or more related
2. Multilateral
instruments and whatever its particular designation.
o Agreements involving more than two parties
1
, Law of Treaties Public International Law
The definition of ‘treaty’ in art. 2(1)(a) VCLT has several implications for the scope of applicability of the
VCLT:
1. VCLT only applies to treaties between states
2. VCLT only applies to written agreements (although, according to art. 3 VCLT, this rule does not
affect the applicability of other agreements)
3. Agreements between states which are governed by specific domestic/municipal law are
excluded from the scope of the VCLT.
International law does not require a particular form for a document to be classified as a treaty, as long
as the parties have intended to create (international) legal obligations. The intention of creating legal
obligations signifies the crucial distinction between formal international instruments (treaties) and
informal international instruments (such as ‘memoranda of understanding’)
- Memorandum of understanding = an agreement between two or more parties outlined in a
formal document. It is not legally binding but signals the willingness of the parties to move
forward with a contract.
Two basic principles:
1. Treaties need to be based on the free consent of states → corollary to the concept of state
sovereignty
2. The freedom of states is not unlimited → once consent to be bound has been expressed and
the treaty has entered into force, the treaty shall be kept by the parties in good faith (pacta
sunt servanda, art. 26 VCLT)
o Even contrary domestic law is not a valid excuse for failing to perform a treaty
obligation (art. 27 VCLT)
The principle of good faith/pacta sunt servanda
One of the most fundamental principles of the law of treaties is that obligations under a treaty should
be performed ‘in good faith’→ principle of pacta sunt servanda
- Underlying reason: states possess full sovereignty and are in no way obligated to enter into
treaty obligations with each other. The fact that states enter into treaty relations out of their free
will indicates that they will perform their treaty obligations in good faith
Codified in art. 26 VCLT: “Every treaty in force is binding upon the parties to it and must be performed
by them in good faith”
- Two main elements:
o The treaty in force is binding upon the parties
o The treaty must be performed by the parties in good faith
- Importance pacta sunt servanda confirmed in Gabcikovo-Nagymaros-case:
Facts:
In 1977, Hungary and Czechoslovakia adopted a treaty on “the construction and operation of the
Gabcikovo-Nagymaros System of Locks”. Both parties would commence building locks in Gabcikovo and
in Nagymaros, each party responsible for the construction of the locks in their own territory. However, the
Hungarian government decides to suspend the construction. Czechoslovakia was independently exploring
other possible ways to continue the operation by itself. One solution found was known as ‘Variant C’. In
1992, Hungary informed Czechoslovakia about its unilateral termination of the Treaty. Czechoslovakia
continued operations on ‘Variant C’. To Hungary, ‘Variant C’ violated its sovereignty and territorial integrity.
According to Slovakia, the continuance of ‘Variant C’ was a lawful countermeasure against Hungary’s
illegal act of suspending and abandoning its works on the Nagymaros-project and the Gabcikovo parts of
the projects for which it was responsible under the Treaty.
Legal question(s)
- Was Hungary allowed to suspend and, later on, abandon its works on the Nagymaros project on
the Gabcikovo parts of the projects for which it was responsible under the Treaty?
- Were the Czech and Slovak Republic entitled to continue the unilateral operations on the
Danube?
- And what are the legal effects on the unilateral termination by Hungary of the Treaty in 1992?
- What are the legal consequences of the aforementioned questions?
When Hungary argued that a fundamental change in environmental awareness, in conjunction with the
fall of communism, ought to release it from a treaty with Slovakia to build a possibly harmful dam in the
Danube river, the Court suggested that the changes had not been entirely unforeseeable and did not
2
