pacta sunt servanda

The basic rule of treaty law: every treaty in force is binding on the parties and must be performed in good faith. It is codified in Article 26 of the Vienna Convention on the Law of Treaties, 1969, and is also part of customary international law, so it binds States that have not joined the Convention. India has not ratified the Vienna Convention but accepts the rule as custom.

The rule is tempered by rebus sic stantibus (fundamental change of circumstances) and by jus cogens: a treaty that conflicts with a peremptory norm is void. In private contract law the same idea appears as the sanctity of contract.

Example

Under pacta sunt servanda a State cannot excuse non-performance of a treaty by pointing to its own domestic law.

In Indian law

• Article 26, Vienna Convention on the Law of Treaties, 1969
• Article 51(c), Constitution of India (State to foster respect for treaty obligations)
• Article 253, Constitution of India (Parliament's power to implement treaties)

See also

treaty · rebus sic stantibus · jus cogens · customary international law

Read more in the study notes

• International law: nature, definition, origin and basis (Public International Law)
• Sources of international law (Public International Law)
• Law of treaties: conclusion, reservations, validity and termination (Public International Law)
• The United Nations: origin, purposes, principles and membership (Public International Law)