The Principle of ‘Pacta Sunt Servanda’

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SUBJECT: The Principle of ‘Pacta Sunt Servanda’

I. Introduction and Purpose of Memo
This memorandum provides a concise analysis of the principle of pacta sunt servanda in international law and its critical implications for the Republic of the Philippines. The purpose is to elucidate this foundational doctrine, its application within the Philippine legal system, and the practical remedies available in the event of its breach by a state party. Understanding this principle is essential for advising on treaty compliance, diplomatic negotiations, and dispute resolution.
II. Definition and Legal Basis
Pacta sunt servanda, a Latin maxim meaning “agreements must be kept,” is the cornerstone of the international law of treaties. It establishes the fundamental obligation that every treaty in force is binding upon the parties to it and must be performed by them in good faith. Its most authoritative codification is found in Article 26 of the 1969 Vienna Convention on the Law of Treaties (VCLT), which states: “Every treaty in force is binding upon the parties to it and must be performed by them in good faith.”
III. Status under Philippine Law
The Philippines is a party to the VCLT, having ratified it in 1972. More significantly, the principle is enshrined in the 1987 Constitution. Article II, Section 2 declares: “The Philippines renounces war as an instrument of national policy, adopts the generally accepted principles of international law as part of the law of the land, and adheres to the policy of peace, equality, justice, freedom, cooperation, and amity with all nations.” The Supreme Court has consistently held that the principle of pacta sunt servanda is one such “generally accepted principle.” Consequently, treaties duly concurred in by the Senate become part of the law of the land and carry the force and effect of domestic law under the doctrine of transformation.
IV. Essential Elements and Scope
The principle imposes two core obligations: (1) the binding force of treaties, and (2) performance in good faith (bona fides). Its scope covers all valid treaties, whether bilateral or multilateral. However, it applies only to treaties “in force” for the state concerned. The obligation is not absolute; it applies only to the parties to the treaty and is subject to the treaty’s own provisions, including mechanisms for amendment, termination, or withdrawal.
V. Limitations and Exceptions
Pacta sunt servanda is not an inflexible rule. The VCLT itself provides legitimate grounds for non-performance or termination, which include:

Material Breach by another party (Article 60);

Supervening Impossibility of Performance (Article 61);

Fundamental Change of Circumstances (Rebus sic stantibus), under strict conditions (Article 62);

Conflict with a Peremptory Norm of International Law (Jus Cogens) (Article 53); and

Invalidity due to error, fraud, corruption, or coercion (Articles 46-52).

Invoking these exceptions is procedurally rigorous and does not unilaterally absolve a state of its obligations without proper legal justification.
VI. Interaction with Philippine Sovereignty
While the principle binds the state, it operates within the framework of national sovereignty. The Philippine Senate’s power to concur in treaty ratification is a sovereign act. Once concurred, the treaty obligation becomes a voluntary limitation on sovereignty, which the state is bound to observe. The Supreme Court, in Bayan v. Zamora, emphasized that the Philippine commitment under treaties like the V.S. Mutual Defense Treaty is a “sovereign act which cannot be unilaterally withdrawn… without a breach of international law.”
VII. Consequences of Breach
A breach of pacta sunt servanda constitutes an internationally wrongful act, engaging the state’s international responsibility. Consequences may include:

Cessation of the wrongful act and assurances and guarantees of non-repetition;

Obligation to make full reparation in the form of restitution, compensation, or satisfaction; and

Lawful countermeasures by the injured state, subject to proportionality.

VIII. Defense of Non-Performance
In any dispute, a state accused of breach may defend its actions by invoking the permissible exceptions under the VCLT (as listed in Section V). The burden of proof lies with the state invoking the exception. It may also argue that its interpretation of the treaty obligation differs, or that the complaining state itself was in prior breach, justifying non-performance as a countermeasure.

IX: Practical Remedies.
For the Republic of the Philippines, practical remedies in addressing issues related to pacta sunt servanda are multi-tiered. Domestically, the primary remedy for perceived conflict lies in judicial review; any private party or government agency may seek Supreme Court interpretation of a treaty’s domestic application and its consistency with the Constitution, as seen in cases like Pimentel v. Executive Secretary. Diplomatically, the first recourse is always negotiation and consultation with the treaty partner to resolve disputes or seek interpretive agreements, which is a direct application of the good faith obligation. If diplomacy fails, the Philippines must resort to the dispute settlement mechanisms specified within the treaty itself, which may include arbitration (e.g., under the U.N. Convention on the Law of the Sea) or adjudication before the International Court of Justice. Where a treaty partner is in material breach, the Philippines may, following the procedures in the VCLT, consider suspending or terminating its own obligations under that treaty as a lawful response. Internally, to prevent inadvertent breach, all government instrumentalities must ensure their acts, including legislation and executive orders, are consistent with the country’s treaty obligations, as non-compliance by any branch constitutes an international wrong attributable to the state.