Philippines' baseline claims riddled with legal holes

On July 29, the Philippine National Mapping and Resource Information Authority (NAMRIA) submitted Chart No 1567, entitled "Bajo de Masinloc and Approach", to the United Nations Division for Ocean Affairs and the Law of the Sea (DOALOS). The submission seeks to establish the so-called "territorial sea baselines" around China's Huangyan Island and its adjacent waters.

The Philippine Department of Foreign Affairs claims that the submission is intended to "uphold international law and reinforce the legal certainty of its maritime entitlement".

But in reality, this action, cloaked in legal language, is both factually unfounded and legally untenable. It is a blatant violation of the fundamental principles of international law.

That Huangyan Island is not part of Philippine territory is a fact grounded in treaty law.

The territorial boundary of the Philippines was clearly defined by a series of international treaties, including the 1898 Treaty of Paris between the United States and Spain, the 1900 Treaty of Washington and the 1930 Convention Between the United States and Great Britain.

These treaties collectively established the boundary of Philippine territory along the meridian of 118 degrees east longitude. Huangyan Island, situated at approximately 117.51 degrees east longitude, falls outside the territorial limits defined by these treaties.

Notably, the Philippines did not assert sovereignty over Huangyan Island for a long time. It was only in the 1990s that the Philippines began illegally incorporating the island into its "territorial claims" based on erroneous historical interpretations and flawed legal arguments.

This shift in position runs counter to the fundamental principles of international law, including pacta sunt servanda (agreements must be kept) and the estoppel doctrine. Under the principle of estoppel, a state cannot contradict positions it had previously acknowledged, particularly regarding territorial sovereignty. Therefore, the Philippines cannot legitimately seek to expand its territory beyond the boundaries already established through binding international treaties.

The Philippines argues that its so-called "territorial sea baselines" are based on Articles 3, 33 and 121 of the United Nations Convention on the Law of the Sea (hereinafter referred to as "UNCLOS"), which concern the territorial sea, the contiguous zone and islands. But this argument is flawed from the outset.

A fundamental principle of the law of the sea is that "the land dominates the sea", which means maritime rights stem from sovereignty over land territory. A state's entitlement to maritime zones presupposes lawful sovereignty over the land feature in question.

Since China has sovereignty over Huangyan Island, the Philippines has no legal basis to unilaterally establish so-called "territorial sea baselines" around the island.

Its attempt to invoke rights under UNCLOS to reinforce a territorial sovereignty claim turns the legal order on its head.

Such a move has no legal effect, nor can it create sovereignty or maritime entitlements where none exist.

The Philippines has drawn these baselines on the basis of the so-called "2016 South China Sea arbitration award" and its subsequent enactment of the Philippine Maritime Zones Act based on that "award". This legal foundation is fundamentally defective.

First, the arbitral tribunal in the South China Sea arbitration acted beyond its jurisdiction and made serious errors in its findings, rendering the "award" null and void and lacking any binding force. China has consistently stated that it neither accepts nor recognizes the award.

In recent years, the Philippines has sought to transform the "arbitral award" into domestic legislation and has used this legislation to establish the so-called "territorial sea baselines". It is an attempt to legitimize an unlawful "arbitral award" by incorporating it into domestic law.

Moreover, a state cannot invoke any domestic law to justify its failure to meet international obligations or to evade international responsibility. The Philippines' legislation therefore cannot override the fundamental principles and rules of international law.

The timing of the Philippines' latest move over Huangyan Island reflects a series of political calculations. First, 2026 marks the tenth anniversary of the so-called "South China Sea arbitration award".

The Philippine government aims to use this occasion to revive international attention to the "award", portray it as legally authoritative, discredit China and increase diplomatic pressure on Beijing.

Second, as the rotating Chair of the Association of Southeast Asian Nations, the Philippines is leveraging its position during the final stage of negotiations on the Code of Conduct in the South China Sea (hereinafter referred to as the "COC").

By provoking disputes over key maritime features, the Philippines aims to inject elements of the "arbitral award" into the future COC and pressure China into making concessions on critical issues, thereby strengthening its bargaining position in the rule-making process.

Third, the Philippines has intensified its activities around Huangyan Island, Ren'ai Jiao and other key maritime features, creating flashpoints to increase pressure on China's maritime law enforcement. This also creates opportunities for external powers, particularly the United States and its allies, to deepen their involvement in South China Sea affairs.

The Philippine government is trying to shift public attention amid sluggish economic performance and domestic governance challenges.

By amplifying the so-called "China threat narrative", it wants to stir nationalist sentiment and use the South China Sea issue as a political tool against its domestic opponents.

China enjoys indisputable sovereignty over Huangyan Island and its adjacent waters.

It lawfully announced and established the territorial sea baselines of Huangyan Island in November 2024 as a legitimate exercise of its sovereignty and maritime rights.

In response to the Philippines' repeated infringements, China has adopted a comprehensive set of countermeasures, including official diplomatic statements, joint naval and air exercises, maritime rights protection and law enforcement operations conducted by the China Coast Guard. It also promulgated the management measures for the Huangyan Island National Nature Reserve on Aug 1, 2026.

The Philippines' unlawful actions cannot change the fact that Huangyan Island is an integral part of China's territory, nor can they weaken China's determination to safeguard its national sovereignty and maritime rights.

In fact, its provocations will only narrow its room for maneuver in the South China Sea, while its unlawful claims will ultimately prove unsustainable.

The author is the assistant director of the Institute for Global Governance, Shanghai Institutes for International Studies.

The views don't necessarily reflect those of China Daily.

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