What is the relation between International Law and Municipal Law?

03 Aug 2025 --
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📘 Relation between International Law and Municipal Law

Definitions:

International Law:
The set of rules and principles that govern relations between sovereign states and other international actors.

Municipal Law:
The domestic law of a state, including its constitution, statutes, regulations, and judicial decisions, that governs individuals and entities within that state.

Relationship Overview:

The relationship between international law and municipal law concerns how international law is applied and enforced within a country’s domestic legal system.

Theories Explaining the Relation

1. Dualism

Treats international law and municipal law as two separate legal systems operating independently.

For an international treaty or norm to have effect domestically, it must be incorporated by legislation.

Example: The United Kingdom follows this approach—treaties don’t automatically become part of domestic law.

2. Monism

Views international law and municipal law as part of a single legal system.

International law automatically becomes part of the municipal law upon ratification or by virtue of constitution.

Example: The Netherlands follows this approach—international law has direct effect domestically.

Practical Implications

Aspect	Dualism	Monism
Relation between laws	Separate legal systems	One integrated legal system
Domestic effect of treaties	Only with implementing legislation	Directly applicable in domestic courts
Enforcement	Courts apply municipal law primarily	Courts can apply international law directly

Constitutional Perspectives

Many countries specify in their constitution how international law relates to domestic law.

For example, India follows a modified dualist system:

International treaties do not automatically become part of Indian law.

Parliament must enact legislation to implement treaty obligations domestically.

However, international law principles can guide judicial interpretation.

Interaction and Conflict

When municipal law conflicts with international law:

In dualist states, municipal law prevails unless changed.

In monist states, international law usually prevails.

States are expected to fulfill their international obligations in good faith (principle of pacta sunt servanda).

Summary Table

Feature	International Law	Municipal Law
Scope	Governs relations between states	Governs relations within the state
Enforcement	Depends on consent and cooperation	Enforced by domestic courts
Relation in Dualism	Separate systems	Must enact laws to implement treaties
Relation in Monism	Part of a unified legal order	Directly applicable