• Atty Neil Simon Silva

The maritime zones of the Philippines: A legal and historical overview


As an archipelagic state and a party to the 1982 United Nations Convention on the Law of the Sea (UNCLOS), the Philippines has or may assert sovereignty over its internal waters, archipelagic waters, and territorial sea, limited enforcement jurisdiction in the contiguous zone, and sovereign rights and jurisdiction in the exclusive economic zone (EEZ) and the continental shelf. These are measured from either the straight baselines of its main archipelago, or from the baselines of its outer territories, including the Kalayaan Island Group (KIG) and Bajo De Masinloc (BDM).


The normative problem for Philippine marine governance is that the Philippines has not yet fully implemented UNCLOS through its legislation; and consequently, its UNCLOS-compliant laws on maritime zones co-exist with statutory vestiges of pre-UNCLOS maritime regimes. The reason for this is best understood in light of the Philippines’ history as a proponent of the theory of mid-ocean archipelagos in the discussions around the first and second law of the sea conferences.

When the Philippines and other archipelagic states proposed a legal regime for mid-ocean archipelagos, it was a concept with little basis in positive law beyond the analogous precedent of the Anglo-Norwegian Fisheries Case. Therefore, to support its theory, the Philippines invoked the unsettled state of the law; the varying security and economic interests of states, which precluded uniformity on the extent of the territorial sea; and its claimed historic rights, based on a maximalist interpretation of the agreements defining its main archipelago. For example, article III of the 1898 Spain-US Treaty of Paris ceding the islands within stated treaty lines was interpreted to have made those lines the “perimetric boundary” of the archipelago, “both land and sea”.


The 1982 UNCLOS would recognize the right of archipelagic states to establish straight archipelagic baselines and to assert sovereignty over the waters within them, subject to easements like passage rights. However, in signing the convention, the Philippines declared that this would not impair its rights under the treaties defining its main archipelago nor its sovereignty over territories like the KIG, and that it reserved the right to amend its laws. This prevented the operation of the general rule in Philippine law that a treaty would amend prior statutes, and left the Philippines with the obligation to harmonize its laws with UNCLOS.


At present, 38 years after UNCLOS was signed and 26 years after it came into effect, the updating of Philippine laws and charts remains incomplete. Thus:

  • The Philippines finally updated the baselines of the territorial sea of the main archipelago through RA 9522. However, it has not yet established baselines for its outer territories, including the KIG and BDM.

  • The Philippines has not yet delineated its archipelagic waters on the landward side vis-a-vis its internal waters.

  • The Philippines’ sovereignty over the territorial sea is asserted in its Constitution and laws, but the measurement of the territorial sea drawn from the main archipelago provided under RA 3046 is inconsistent with UNCLOS.

  • EO 389 (1950) asserted the Philippines’ jurisdiction in contiguous waters, under then-prevailing customary law, but an updated law is necessary with the effectivity of UNCLOS. However, the latest statute dealing with the contiguous zone, RA 7942, defined it in relation to mining and not law enforcement as provided under UNCLOS; and the metes and bounds of the contiguous zone remain unpublished.

  • The Constitution and laws like PD 1599 and RA 8550 as amended asserted the Philippines’ sovereign rights and jurisdiction over its EEZ, but the metes and bounds of the EEZ remain unpublished except opposite Indonesia. FAO 23, s. 2019 of the Bureau of Fisheries and Aquatic Resources did include the delineation of the Philippine EEZ but was not published in compliance with UNCLOS.

  • The Philippines has asserted sovereign rights and jurisdiction over the continental shelf but has not published its metes and bounds except in the Philippine Rise Region. Moreover, many laws, like PD 1599, RA 7942, and arguably RA 8550 as amended, assimilate the legal regime of the continental shelf to that of the EEZ; consequently, for example, the 1995 mining law does not cover the extended continental shelf.

  • PD 1596 declaring the KIG part of Philippine territory also established a polygon in which the Philippines would have sovereignty over the “sea-bed, sub-soil, continental margin.” This polygon is now inconsistent with the UNCLOS, but its legal status remains unclear since RA 9522 did not expressly amend PD 1596.

The subsistence of these legal ambiguities is untenable as a matter of law and policy. International law requires the Philippines to perform its agreements in good faith, under the principle pacta sunt servanda; and under municipal law, its adherence to UNCLOS has been categorically affirmed by the Supreme Court. Moreover, the maximalist interpretation of the International Treaty Limits contained in pre-UNCLOS law, which was developed to support the archipelagic doctrine in multilateral negotiations, is unnecessary now that the archipelagic doctrine is an established conventional norm. Furthermore, pre-UNCLOS laws on the bounds of the territorial sea and on the KIG maritime polygon are ineffective under international law; for as the 12 July 2016 Award in the South China Sea Arbitration pointed out, UNCLOS superseded incompatible maritime claims, even those premised on alleged historical rights without international acquiescence.


Therefore, from a normative perspective, what must be done? First, the Philippines must enact a Maritime Zones Law codifying and updating its scattered statutes on maritime zones in accordance with UNCLOS. Second, it must publish the metes and bounds of its maritime zones, both those drawn from its main archipelago and those drawn from its outer territories. It is conceded that this second task will remain incomplete for some time due to the difficulty of mapping areas controlled by foreign powers, the need to negotiate overlaps with neighboring states, and the issues arising from subsisting territorial disputes. Nonetheless, as a nation that adheres to the rule of law and whose interests are protected by the rules-based global order, the Philippines is required by natural and positive law and the demands of realpolitik to fully harmonize its laws with UNCLOS.

For the sake of its people and its sovereignty, it can do no less.

*This article was commissioned by ARS in behalf of the Foundation for the National Interest through the support of The Asia Foundation for the project on "Governance, Security, and Development in the Philippine Maritime Domain.i

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