| SUBJECT: The Rule on ‘The VCLT’ (Vienna Convention on the Law of Treaties) |
I. Introduction
This memorandum provides an exhaustive analysis of the rule on the Vienna Convention on the Law of Treaties (VCLT), adopted on 23 May 1969 and entered into force on 27 January 1980. The VCLT is widely recognized as the codification of the customary international law governing treaties between states. Its provisions are considered authoritative for the interpretation, application, and termination of treaties, serving as the primary framework for treaty relations in public international law. This research will detail its key provisions, jurisprudence, and its application within the Philippine legal system.
II. Statement of Issues
The primary issues addressed are: (1) the definition and scope of a treaty under the VCLT; (2) the rules governing the conclusion and entry into force of treaties; (3) the principles of interpretation of treaties; (4) the rules on reservations; (5) the grounds for invalidity, termination, and suspension of treaties; and (6) the application of the VCLT within the Philippine constitutional and legal framework.
III. Applicable Laws and Rules
The primary applicable law is the Vienna Convention on the Law of Treaties (1969). Relevant provisions of the 1987 Philippine Constitution, particularly Article II, Section 2, and Article VII, Sections 21 and 25, are applicable. The Philippine Treaty Law as embodied in Executive Order No. 459, s. 1997 (Prescribing Guidelines and Procedures for the Negotiation of International Agreements and their Ratification) is also pertinent. Customary international law principles codified in the VCLT are applicable to the Philippines regardless of its specific ratification status concerning certain provisions.
IV. Facts
The Philippines signed the VCLT on 23 May 1969 and ratified it on 15 November 1972. The instrument of ratification was deposited on 15 November 1972, and the Convention entered into force for the Philippines on 27 January 1980. The VCLT applies to treaties concluded by states after its entry into force for those states. Its provisions are routinely invoked before Philippine courts and in the state’s diplomatic practice. The Supreme Court has consistently held that the provisions of the VCLT, reflecting customary international law, form part of the law of the land under the incorporation clause of the Constitution.
V. Discussion
The VCLT establishes a comprehensive regime for the life cycle of a treaty. A treaty is defined as “an international agreement concluded between States in written form and governed by international law, whether embodied in a single instrument or in two or more related instruments and whatever its particular designation” (Article 2(1)(a)). The Convention covers all stages: negotiation, authentication, consent to be bound (through ratification, accession, etc.), entry into force, application, interpretation, amendment, and invalidity or termination.
A cornerstone of the VCLT is its rules on interpretation (Articles 31-33). The general rule (Article 31(1)) requires a treaty to be interpreted “in good faith in accordance with the ordinary meaning to be given to the terms of the treaty in their context and in the light of its object and purpose.” This is a holistic approach considering the text, context, and travaux préparatoires as a supplementary means of interpretation.
The rules on reservations (Articles 19-23) allow a state to unilaterally exclude or modify the legal effect of certain provisions when becoming a party, provided the reservation is not prohibited by the treaty, incompatible with its object and purpose, or, in cases where the treaty is between a limited number of parties, not accepted by all parties.
Part V of the VCLT details grounds for invalidity (e.g., error, fraud, corruption, coercion, conflict with a peremptory norm (jus cogens)) and for termination or suspension (e.g., material breach, supervening impossibility of performance, fundamental change of circumstances (rebus sic stantibus)).
VI. Application to Philippine Jurisprudence
The Philippine Supreme Court has authoritatively applied the VCLT. In Bayan v. Executive Secretary, the Court used the VCLT’s definition of a treaty to distinguish it from an executive agreement. In Republic v. Sandiganbayan, the Court invoked the principle of pacta sunt servanda (Article 26) to uphold the binding nature of international agreements. Most notably, in Secretary of Justice v. Lantion, the Court extensively cited Articles 31 and 32 of the VCLT on treaty interpretation to construe the extradition treaty between the Philippines and the United States, emphasizing the primacy of the text in its context and in light of its object and purpose.
VII. Comparative Analysis of Key Concepts
The following table compares key treaty-related concepts as understood under general international law prior to the VCLT and as codified or clarified by the VCLT.
| Concept | Pre-VCLT Understanding / Customary Law | VCLT Codification / Rule (1969) |
|---|---|---|
| Treaty Definition | Varied and inconsistent; relied on diverse nomenclature (convention, pact, covenant, etc.). | Article 2(1)(a): A unified, objective definition based on substance over form. |
| Interpretation | Subjective methods; schools of thought (textual, intentional, teleological). | Articles 31-33: A single, integrated general rule emphasizing text, context, and object and purpose, with travaux préparatoires as supplementary. |
| Reservations | The “Pan-American” vs. “European” rule; the object and purpose test from the ICJ in the Reservations to the Genocide Convention case. | Articles 19-23: A flexible regime centered on the compatibility with the treaty’s object and purpose. |
| Jus Cogens | An emerging concept of peremptory norms from which no derogation is permitted. | Article 53: Explicitly defines a peremptory norm of general international law (jus cogens) and voids treaties conflicting with it. |
| Fundamental Change of Circumstances | The doctrine of rebus sic stantibus was controversial and rarely invoked successfully. | Article 62: Strictly circumscribes the conditions for invoking a fundamental change of circumstances as a ground for termination. |
VIII. Legal Effects and Implications for the Philippines
As a party to the VCLT, the Philippines is bound by its provisions. The Convention provides the legal yardstick for all Philippine treaty actions. Domestically, the VCLT’s principles guide the Executive in treaty negotiation and the Senate in its concurrence under Article VII, Section 21 of the Constitution. The judiciary relies on it for interpreting international agreements. Furthermore, the VCLT’s status as customary international law means its core provisions (e.g., pacta sunt servanda, rules of interpretation) bind the Philippines in its relations with all states, even those not party to the Convention.
IX. Potential Counterarguments and Limitations
A potential counterargument is that the VCLT is not universally applicable ratione temporis, as it applies only to treaties concluded after its entry into force for the states concerned (Article 4). However, its provisions are deemed declaratory of customary international law, thus applicable to earlier treaties as custom. Another limitation is that the VCLT governs treaties between states only; treaties with or between international organizations are covered by the separate 1986 Vienna Convention. Furthermore, the VCLT does not address the validity of a treaty from the perspective of domestic law (Article 46), a point of relevance in Philippine constitutional law regarding the necessity of Senate concurrence.
X. Conclusion
The Vienna Convention on the Law of Treaties is the foundational instrument of the modern law of treaties. Its comprehensive codification of customary international law provides certainty, stability, and good faith in international relations. For the Philippines, the VCLT is both a binding international agreement and a reflection of customary international law incorporated into domestic law. Its rules on interpretation, validity, and termination are indispensable tools for the Executive, Legislative, and Judicial branches in fulfilling the state’s international obligations and asserting its rights under the pacta sunt servanda principle.
