COMPREHENSIVE PUBLIC INTERNATIONAL
LAW AND INTERNATIONAL LEGAL SYSTEMS
PRACTICE EXAM QUESTIONS AND ANSWERS -
UPDATED 2026 (GRADED A+)
Subject: Public International Law
Subtopic: Sources of International Law and State Sovereignty
Question 1: Under Article 38(1) of the Statute of the International Court of
Justice, which source is considered primary evidence of rules expressly recognized
by states?
A) Judicial decisions
B) Teachings of publicists
C) International conventions
D) Equity principles
Correct Answer: C) - International conventions
Rationale: Article 38(1)(a) identifies international conventions, whether general or
particular, as primary sources establishing rules expressly recognized by
consenting states. Judicial decisions and scholarly writings are subsidiary means
under Article 38(1)(d), while equity is not categorized as a formal primary source
unless parties agree to ex aequo et bono adjudication.
Question 2: Which principle most fundamentally underpins the binding force of
treaties in international law?
A) Jus cogens
B) Pacta sunt servanda
C) Rebus sic stantibus
D) Uti possidetis juris
Correct Answer: B) - Pacta sunt servanda
Rationale: Pacta sunt servanda, codified in Article 26 of the Vienna Convention on
the Law of Treaties, requires treaties in force to be performed in good faith. Jus
,cogens concerns peremptory norms, rebus sic stantibus concerns fundamental
changes of circumstances, and uti possidetis juris relates to territorial boundaries
following decolonization.
Question 3: Which criterion is essential for the formation of customary
international law?
A) Ratification by all UN member states
B) General Assembly approval
C) State practice accompanied by opinio juris
D) Judicial recognition by the ICJ exclusively
Correct Answer: C) - State practice accompanied by opinio juris
Rationale: Customary international law arises from consistent state practice
combined with opinio juris, the belief that such practice is legally obligatory. Mere
repetition without legal conviction is insufficient. Universal ratification or judicial
recognition is unnecessary for customary norm formation.
Question 4: Which doctrine limits a state’s ability to invoke domestic law as
justification for failure to perform treaty obligations?
A) Lotus principle
B) Act of state doctrine
C) Monism
D) Article 27 of the Vienna Convention on the Law of Treaties
Correct Answer: D) - Article 27 of the Vienna Convention on the Law of Treaties
Rationale: Article 27 expressly prohibits states from invoking internal law as
justification for failure to perform treaty obligations. This reinforces international
legal stability and prevents unilateral avoidance of commitments.
Question 5: Which of the following best characterizes jus cogens norms?
A) Optional principles applicable only to regional organizations
B) Norms binding solely upon treaty parties
,C) Peremptory norms from which no derogation is permitted
D) Political obligations without legal effect
Correct Answer: C) - Peremptory norms from which no derogation is permitted
Rationale: Jus cogens norms occupy the highest hierarchical status in international
law and invalidate conflicting treaty provisions. Examples include prohibitions on
genocide, slavery, torture, and aggressive war.
Question 6: In the context of statehood under the Montevideo Convention, which
element is NOT traditionally required?
A) Permanent population
B) Defined territory
C) Democratic government
D) Capacity to enter relations with other states
Correct Answer: C) - Democratic government
Rationale: The Montevideo Convention identifies four classical criteria for
statehood: permanent population, defined territory, government, and capacity for
international relations. Democratic governance is not a formal legal prerequisite
for statehood.
Question 7: Which principle was affirmed in the SS Lotus Case regarding state
sovereignty?
A) States may act only when international law expressly permits
B) States possess residual freedom unless expressly prohibited by international
law
C) Sovereignty is subordinate to UN resolutions in all circumstances
D) Domestic law automatically supersedes international obligations
Correct Answer: B) - States possess residual freedom unless expressly prohibited
by international law
Rationale: The Permanent Court of International Justice in the SS Lotus Case
emphasized that restrictions upon state sovereignty cannot be presumed and that
states retain freedom absent prohibitive rules.
, Question 8: Which mode of treaty interpretation is emphasized by Article 31 of
the Vienna Convention on the Law of Treaties?
A) Purely textual interpretation without context
B) Strictly historical interpretation
C) Good-faith interpretation according to ordinary meaning, context, and object
and purpose
D) Interpretation solely according to subsequent judicial decisions
Correct Answer: C) - Good-faith interpretation according to ordinary meaning,
context, and object and purpose
Rationale: Article 31 establishes the general rule of treaty interpretation
emphasizing ordinary meaning in context and in light of the treaty’s object and
purpose, interpreted in good faith.
Question 9: Which legal consequence arises if a treaty conflicts with a jus cogens
norm at the time of conclusion?
A) The treaty remains valid until challenged before the ICJ
B) The conflicting provision alone is suspended
C) The treaty is void ab initio
D) The treaty becomes regionally enforceable only
Correct Answer: C) - The treaty is void ab initio
Rationale: Under Article 53 of the Vienna Convention, treaties conflicting with
existing jus cogens norms are void from inception because peremptory norms
override consensual obligations.
Question 10: Which principle prohibits intervention in matters within the
domestic jurisdiction of states?
A) Self-determination
B) Non-intervention
C) Universal jurisdiction
D) Collective security
LAW AND INTERNATIONAL LEGAL SYSTEMS
PRACTICE EXAM QUESTIONS AND ANSWERS -
UPDATED 2026 (GRADED A+)
Subject: Public International Law
Subtopic: Sources of International Law and State Sovereignty
Question 1: Under Article 38(1) of the Statute of the International Court of
Justice, which source is considered primary evidence of rules expressly recognized
by states?
A) Judicial decisions
B) Teachings of publicists
C) International conventions
D) Equity principles
Correct Answer: C) - International conventions
Rationale: Article 38(1)(a) identifies international conventions, whether general or
particular, as primary sources establishing rules expressly recognized by
consenting states. Judicial decisions and scholarly writings are subsidiary means
under Article 38(1)(d), while equity is not categorized as a formal primary source
unless parties agree to ex aequo et bono adjudication.
Question 2: Which principle most fundamentally underpins the binding force of
treaties in international law?
A) Jus cogens
B) Pacta sunt servanda
C) Rebus sic stantibus
D) Uti possidetis juris
Correct Answer: B) - Pacta sunt servanda
Rationale: Pacta sunt servanda, codified in Article 26 of the Vienna Convention on
the Law of Treaties, requires treaties in force to be performed in good faith. Jus
,cogens concerns peremptory norms, rebus sic stantibus concerns fundamental
changes of circumstances, and uti possidetis juris relates to territorial boundaries
following decolonization.
Question 3: Which criterion is essential for the formation of customary
international law?
A) Ratification by all UN member states
B) General Assembly approval
C) State practice accompanied by opinio juris
D) Judicial recognition by the ICJ exclusively
Correct Answer: C) - State practice accompanied by opinio juris
Rationale: Customary international law arises from consistent state practice
combined with opinio juris, the belief that such practice is legally obligatory. Mere
repetition without legal conviction is insufficient. Universal ratification or judicial
recognition is unnecessary for customary norm formation.
Question 4: Which doctrine limits a state’s ability to invoke domestic law as
justification for failure to perform treaty obligations?
A) Lotus principle
B) Act of state doctrine
C) Monism
D) Article 27 of the Vienna Convention on the Law of Treaties
Correct Answer: D) - Article 27 of the Vienna Convention on the Law of Treaties
Rationale: Article 27 expressly prohibits states from invoking internal law as
justification for failure to perform treaty obligations. This reinforces international
legal stability and prevents unilateral avoidance of commitments.
Question 5: Which of the following best characterizes jus cogens norms?
A) Optional principles applicable only to regional organizations
B) Norms binding solely upon treaty parties
,C) Peremptory norms from which no derogation is permitted
D) Political obligations without legal effect
Correct Answer: C) - Peremptory norms from which no derogation is permitted
Rationale: Jus cogens norms occupy the highest hierarchical status in international
law and invalidate conflicting treaty provisions. Examples include prohibitions on
genocide, slavery, torture, and aggressive war.
Question 6: In the context of statehood under the Montevideo Convention, which
element is NOT traditionally required?
A) Permanent population
B) Defined territory
C) Democratic government
D) Capacity to enter relations with other states
Correct Answer: C) - Democratic government
Rationale: The Montevideo Convention identifies four classical criteria for
statehood: permanent population, defined territory, government, and capacity for
international relations. Democratic governance is not a formal legal prerequisite
for statehood.
Question 7: Which principle was affirmed in the SS Lotus Case regarding state
sovereignty?
A) States may act only when international law expressly permits
B) States possess residual freedom unless expressly prohibited by international
law
C) Sovereignty is subordinate to UN resolutions in all circumstances
D) Domestic law automatically supersedes international obligations
Correct Answer: B) - States possess residual freedom unless expressly prohibited
by international law
Rationale: The Permanent Court of International Justice in the SS Lotus Case
emphasized that restrictions upon state sovereignty cannot be presumed and that
states retain freedom absent prohibitive rules.
, Question 8: Which mode of treaty interpretation is emphasized by Article 31 of
the Vienna Convention on the Law of Treaties?
A) Purely textual interpretation without context
B) Strictly historical interpretation
C) Good-faith interpretation according to ordinary meaning, context, and object
and purpose
D) Interpretation solely according to subsequent judicial decisions
Correct Answer: C) - Good-faith interpretation according to ordinary meaning,
context, and object and purpose
Rationale: Article 31 establishes the general rule of treaty interpretation
emphasizing ordinary meaning in context and in light of the treaty’s object and
purpose, interpreted in good faith.
Question 9: Which legal consequence arises if a treaty conflicts with a jus cogens
norm at the time of conclusion?
A) The treaty remains valid until challenged before the ICJ
B) The conflicting provision alone is suspended
C) The treaty is void ab initio
D) The treaty becomes regionally enforceable only
Correct Answer: C) - The treaty is void ab initio
Rationale: Under Article 53 of the Vienna Convention, treaties conflicting with
existing jus cogens norms are void from inception because peremptory norms
override consensual obligations.
Question 10: Which principle prohibits intervention in matters within the
domestic jurisdiction of states?
A) Self-determination
B) Non-intervention
C) Universal jurisdiction
D) Collective security
