Object and purpose is a foundational concept in the law of treaties, codified principally in the Vienna Convention on the Law of Treaties (VCLT, 1969). It functions as a limiting standard in several distinct contexts. Under Article 19(c), a state may not formulate a reservation that is incompatible with the treaty's object and purpose. Under Article 18, a state that has signed but not yet ratified a treaty is obliged to refrain from acts that would defeat its object and purpose. Under Article 31(1), treaties must be interpreted in good faith in light of their object and purpose, alongside ordinary meaning and context.
The concept gained doctrinal weight through the International Court of Justice's 1951 Advisory Opinion on Reservations to the Genocide Convention, which held that reservations incompatible with a convention's object and purpose cannot bind other parties. Later instruments, including the ILC's 2011 Guide to Practice on Reservations to Treaties, elaborated how to identify the object and purpose: typically by examining the treaty's title, preamble, central operative provisions, and travaux préparatoires.
In practice, object and purpose is invoked when:
- A state lodges a sweeping reservation to a human rights treaty (e.g., reservations to CEDAW or the ICCPR) and other parties object;
- A signatory takes hostile action before ratification, as the United States argued regarding the Rome Statute in 2002 when it "unsigned";
- Dispute settlement bodies must choose between competing interpretations of ambiguous treaty text.
The standard is deliberately flexible, leaving substantial room for diplomatic contestation. Critics note that determining a treaty's object and purpose can itself be politicized, particularly for multilateral instruments with broad, aspirational preambles. Nonetheless, the concept remains central to treaty negotiation, reservation practice, and judicial interpretation.
Example
When the United States notified the UN Secretary-General in May 2002 that it did not intend to become a party to the Rome Statute, it sought to release itself from the Article 18 obligation not to defeat the treaty's object and purpose.