Introduction

The 1987 Constitution of the Republic of the Philippines establishes a framework for the interplay between domestic law and international law, reflecting the country's commitment to both sovereignty and global cooperation. This article explores the binding nature of these legal systems within the Philippine jurisdiction, examining constitutional provisions, doctrinal principles, judicial interpretations, and practical implications. It addresses how domestic laws—encompassing the Constitution, statutes, executive issuances, and local ordinances—are inherently binding, while international law gains domestic enforceability through incorporation or transformation mechanisms. The analysis is rooted in the Philippine legal tradition, which balances national interests with adherence to international norms, particularly in a post-colonial context influenced by civil law and common law elements.

The Supremacy and Binding Nature of Domestic Law

Domestic law in the Philippines forms the foundational legal order, with the 1987 Constitution as its apex. Article II, Section 1 declares that "sovereignty resides in the people and all government authority emanates from them," underscoring that domestic laws derive their binding force from popular will as expressed through democratic processes.

Constitutional Supremacy

The Constitution is the supreme law of the land, as affirmed in Article VIII, Section 5(2)(a), which empowers the Supreme Court to review acts for constitutionality. All other domestic laws must conform to it; any inconsistency renders them void. This principle ensures that statutes passed by Congress, executive orders issued by the President, administrative regulations, and local government ordinances are binding only insofar as they align with constitutional mandates. For instance, laws must respect fundamental rights under the Bill of Rights (Article III), such as due process and equal protection.

Hierarchy of Domestic Laws

Below the Constitution lies a hierarchy:

Statutes (Republic Acts): Enacted by Congress under Article VI, these are binding nationwide unless declared unconstitutional. They cover civil, criminal, commercial, and administrative matters.
Executive Issuances: Presidential decrees (from martial law era, if not repealed), executive orders, and proclamations are binding as long as they implement laws and do not exceed delegated authority (Article VII, Section 17).
Administrative Rules: Issued by agencies under delegated legislative power, these have the force of law if within statutory bounds.
Local Ordinances: Enacted by local government units under the Local Government Code (Republic Act No. 7160), binding within their jurisdictions but subject to national laws.

Domestic laws bind all persons within Philippine territory, including citizens, residents, and aliens, under the principle of territoriality (Article 14, Civil Code). Extraterritorial application is limited, such as for crimes under Article 2 of the Revised Penal Code. Enforcement relies on the judiciary, with the Supreme Court as the final arbiter (Article VIII).

Incorporation of International Law into the Philippine Legal System

The 1987 Constitution explicitly integrates international law, distinguishing between customary international law and treaty-based obligations. This reflects the Philippines' dualist approach with monist elements, where international law does not automatically supersede domestic law but can be directly applicable under certain conditions.

Generally Accepted Principles of International Law

Article II, Section 2 provides: "The Philippines... adopts the generally accepted principles of international law as part of the law of the land." This embodies the doctrine of incorporation, automatically making customary international law (CIL) and general principles binding without need for legislative action. CIL includes norms like pacta sunt servanda (treaties must be observed in good faith), sovereign immunity, and prohibitions on genocide or torture.

Judicial application is evident in cases like Mejoff v. Director of Prisons (1951), where the Supreme Court invoked the Universal Declaration of Human Rights as part of the law of the land, despite it not being a treaty. Similarly, in Kuroda v. Jalandoni (1949), war crimes tribunals applied international humanitarian law directly. Under the 1987 Constitution, this provision has been used to enforce environmental norms (e.g., Oposa v. Factoran, 1993, invoking intergenerational equity) and human rights (e.g., Secretary of Justice v. Lantion, 2000, on extradition).

However, these principles must not conflict with the Constitution. In Ichong v. Hernandez (1957), the Court upheld a domestic law over an alleged international norm, emphasizing constitutional supremacy.

Treaties and International Agreements

For treaties, the Philippines follows the doctrine of transformation, requiring domestic action for enforceability. Article VII, Section 21 states: "No treaty or international agreement shall be valid and effective unless concurred in by at least two-thirds of all the Members of the Senate." This transforms international commitments into domestic law upon ratification.

Once concurred, treaties have the force of statutes. In Gonzales v. Hechanova (1963), the Court treated an executive agreement as equivalent to a treaty. However, distinctions exist: treaties require Senate concurrence for formal, binding pacts, while executive agreements (under presidential authority, Article VII, Section 1) handle routine matters without it, as clarified in USAFFE Veterans Association v. Treasurer (1959).

Binding treaties include the UN Charter, WTO agreements, and human rights conventions like the ICCPR. They bind the state internationally under the Vienna Convention on the Law of Treaties (ratified by the Philippines), but domestically, enforcement depends on implementing legislation if self-executing provisions are absent. Self-executing treaties are directly applicable (e.g., Pharmaceutical and Health Care Association v. Duque, 2007, on WTO TRIPS Agreement), while non-self-executing ones require statutes (e.g., Republic Act No. 9851 for international humanitarian law).

Interplay and Conflicts Between International and Domestic Law

Harmony and Interpretation

The Constitution promotes harmony: Article II, Section 2 mandates adherence to peace and cooperation. Courts apply the principle of harmonious construction, interpreting domestic laws to align with international obligations where possible. In Tañada v. Angara (1997), the Supreme Court upheld WTO accession, ruling it consistent with economic sovereignty under Article XII.

Resolution of Conflicts

In conflicts:

Constitution Prevails: International law yields to the Constitution. In Bayan v. Zamora (2000), the Visiting Forces Agreement (VFA) was scrutinized against Article XVIII, Section 25 (on foreign military bases), but upheld as a treaty.
Treaties vs. Statutes: Under the "last in time" rule, later enactments prevail. However, the Court favors international compliance (e.g., Abbas v. COMELEC, 1999).
Customary Law vs. Domestic Law: CIL is subordinate to statutes but can inform interpretation. In Saguisag v. Ochoa (2016), the Enhanced Defense Cooperation Agreement (EDCA) was deemed an executive agreement implementing existing treaties, not requiring new Senate concurrence.

Key cases illustrate tensions:

Pimentel v. Executive Secretary (2005): Mandated Senate concurrence for the Rome Statute of the ICC, delaying ratification.
Pangilinan v. Cayetano (2021): Upheld the withdrawal from the ICC without Senate approval, as withdrawal isn't specified in Article VII, Section 21, prioritizing executive foreign affairs power.
Province of North Cotabato v. Government (2008): Applied international law on self-determination but voided the MOA-AD for constitutional violations.

Practical Implications and Enforcement Mechanisms

Judicial Enforcement

The judiciary enforces both systems. Article VIII, Section 1 defines judicial power to include settling controversies involving rights under treaties. The Supreme Court has original jurisdiction over cases involving ambassadors (Article VIII, Section 5(1)) and can issue writs like amparo for human rights violations incorporating international standards (Rule on the Writ of Amparo, 2007).

Executive and Legislative Roles

The President conducts foreign affairs (Article VII, Section 1), negotiating treaties, but legislative concurrence ensures democratic checks. Congress enacts implementing laws, such as Republic Act No. 9372 (Human Security Act) for anti-terrorism conventions.

Challenges and Criticisms

Challenges include delays in ratification (e.g., CEDAW reservations), conflicts with sovereignty (e.g., South China Sea arbitration under UNCLOS, enforced in Magallona v. Ermita, 2011), and selective application. Critics argue incorporation favors Western norms, potentially undermining cultural sovereignty, while proponents see it as essential for global integration.

Conclusion

Under the 1987 Constitution, domestic law is inherently binding as the expression of sovereign will, with the Constitution supreme. International law binds through incorporation of general principles and transformation of treaties, fostering a system where the Philippines honors global commitments without compromising national supremacy. This dual framework, shaped by historical experiences like colonial rule and martial law, ensures legal stability while adapting to international dynamics. Judicial precedents continue to refine this balance, emphasizing that while international law enriches the domestic order, it remains subservient to constitutional imperatives.