Treaties: How Nations Bind Themselves

A treaty is a written agreement between states, or between states and international organizations, that creates rights and duties under international law. Treaties are the closest thing the international order possesses to legislation. Through them, nations fix boundaries, lower tariffs, renounce weapons, protect refugees, and regulate everything from the telegraph wires of the nineteenth century to the data cables of the twenty-first.

The rules governing these instruments are themselves codified in a treaty, the Vienna Convention on the Law of Treaties of 1969, which largely restated older customary practice. Its central idea is expressed in the ancient maxim that agreements must be kept: once a state has freely consented to be bound, it must perform its obligations in good faith, and it may not invoke its internal law as an excuse for failure.

pacta sunt servanda

Yet treaty law is not rigid. It supplies orderly methods for entering commitments, qualifying them, interpreting them, and, when necessary, leaving them. Understanding those methods explains how a community of sovereign states manages to make promises that outlast the governments that sign them.

Formation and Consent

Treaty-making begins with negotiation, usually conducted by diplomats holding authority from their governments, known as full powers. When the text is settled, it is adopted and often signed. Signature alone may bind a state in some instruments, but for major treaties it is typically only a preliminary act. The decisive step is ratification, acceptance, or approval, by which the state confirms, often after parliamentary approval at home, that it consents to be bound. Multilateral conventions take effect when a set number of states have deposited their consent with a designated depositary.

States frequently attach reservations, statements that exclude or modify particular provisions as they apply to the reserving state. Reservations keep broad treaties politically possible, but the law polices them: a reservation incompatible with the object and purpose of the treaty is not permitted, and other states may object. The resulting web of acceptances and objections can make a single convention apply in slightly different terms between different pairs of parties.

Interpretation, Breach, and Exit

Interpretation begins with the text, read in good faith according to the ordinary meaning of its terms in their context and in light of the treaty's object and purpose. Preparatory work and the circumstances of conclusion may be consulted to confirm meaning or to resolve ambiguity. Because treaties are living instruments, courts and tribunals sometimes read them in light of subsequent practice and evolving standards, particularly for human rights instruments.

A material breach by one party may entitle others to suspend or terminate the treaty as between themselves and the defaulting state, though humanitarian provisions are shielded from reprisal. Treaties may also end by consent, by the conclusion of a later treaty on the same subject, or through doctrines of impossibility and fundamental change of circumstances, both deliberately narrow. Many modern treaties include express withdrawal clauses, and their use reminds us that consent, once given, can also be lawfully withdrawn.

This overview is educational and not legal advice.