On November 8, Philippine president Ferdinand Marcos Jr. signed into law two pieces of legislation: the Philippine Maritime Zones Act and the Philippine Archipelagic Sea Lanes Act. The laws elaborate Philippine maritime claims, including in the South China Sea, ensuring they are in line with international law. These two pieces of legislation were quickly condemned by Beijing, which responded on November 10 by publishing territorial baselines around Scarborough Shoal, a disputed atoll in the South China Sea that China seized from Philippine control in 2012 and which remains the site of frequent confrontations between their vessels.
These events cap a series of South China Sea legal developments in recent months clarifying Southeast Asian claims to the waterway under international law. Those efforts contrast with Beijing’s continued refusal to bring its claims into accordance with international law. That growing divide carries important implications for the future of the disputes.
Q1: How do the new Philippine maritime acts impact its position in the South China Sea?
A1: The Philippine Maritime Zones Act does not change the Philippines’ claims in the South China Sea, but it does clarify them while enshrining the tenets of the United Nations Convention on the Law of the Sea (UNCLOS) and the findings of the 2016 South China Sea arbitration into domestic law. This insulates the Philippines’ claims from future administrations that might, like that of previous president Rodrigo Duterte, seek to shelve the findings of the arbitral award in the interest of relations with China. It also provides a basis for other claimants to negotiate and delimit maritime boundaries with the Philippines and resolves ambiguities in how the Philippines distinguishes its various maritime zones.
The Philippine Archipelagic Sea Lanes Act establishes three designated passages for foreign vessels to navigate through the Philippine archipelago. UNCLOS dictates that archipelagic states like the Philippines must allow foreign vessels “archipelagic sea lane passage”—a right to transit in their normal mode of operation rather than the more limited “innocent passage” permitted in the territorial sea—through “routes normally used for international navigation.” In failing to designate archipelagic sea lanes, the Philippines had previously left it to foreign vessels to decide for themselves where such routes were. This led to frequent disagreements even with close partners, including regular freedom of navigation operations by U.S. Navy vessels through Philippine waters. The new act will help reduce those tensions and will allow the Philippines to better enforce its laws against Chinese military vessels, which have, in recent years, repeatedly lingered inside the archipelago without permission. But the designation of only three archipelagic sea lanes is a significant reduction from the number of transit routes in common use. This will likely cause pushback from the International Maritime Organization, which must review the act before the Philippines can begin enforcement.
Q2: What is the significance of China’s publication of baselines around Scarborough Shoal?
A2: In response to the passage of the Philippine maritime laws, China published baselines around Scarborough Shoal on November 10. The publication was a signal of China’s determination to assert its own claims in the South China Sea, a message given added effect by the fact that Beijing wrested control of Scarborough from Manila in 2012. Beyond the symbolic timing, a baseline claim around Scarborough Shoal is not all that surprising, though the details matter. China has since 1996 said that it would eventually declare baselines around what it calls the Nansha Qundao (Spratly Islands), Dongsha Qundao (Pratas Reef), and Zhongsha Qundao (Scarborough Shoal and underwater features including Macclesfield Bank).
It is notable that the new baselines are limited to Scarborough Shoal and drawn largely in line with international practice. This contrasts with the wildly excessive baselines China drew around the Paracel Islands (Xisha Qundao) in 1996. The Chinese legal community has spent the last several years promoting a new justification for its claims based on a novel concept of “offshore archipelagos.” They argue that each of the four sha, or island groups, Beijing claims in the South China Sea should be treated as a single unit with three major features: the islands and reefs of each group should be connected by straight baselines (which these lawyers argue do not have to follow any of the limits set out in UNCLOS); underwater features within those baselines can therefore be claimed as sovereign territory; and the ability of the island groups to “sustain human habitation”—the key test for whether an island is entitled to a full 200-nautical-mile exclusive economic zone and continental shelf—should be judged based on the group as a whole rather than any individual island. All of this is in contravention of both UNCLOS and the 2016 arbitral award, and the U.S. Department of State dedicated an entire annex of its Limits in the Seas series of legal analyses to debunking it.
Beijing has had little success selling the international community on this newest justification for its claims. That may explain why the new Scarborough baselines are not the most extreme versions China could have drawn. Had Beijing chosen to enclose the entire Zhongsha “island group,” Scarborough Shoal would have been just the easternmost corner of a much larger set of straight baselines around Macclesfield Bank and other underwater features. The newly published baselines suggest Beijing concluded that using underwater features as basepoints would be a step too far. That doesn’t necessarily mean that China will not someday use the outermost underwater features it claims in the south, such as James Shoal off Malaysia and Vanguard Bank off Vietnam, as basepoints for the Spratly Islands, but it gives hope.
As for Scarborough Shoal itself, the basepoints don’t significantly alter the state of the dispute. Sovereignty over the feature is still contested by China and the Philippines (and Taiwan) since that issue was beyond the jurisdiction of the 2016 arbitral award. Beijing still claims a 12-nautical-mile territorial sea and 200-nautical-mile exclusive economic zone and continental shelf from the atoll, despite the award declaring that Scarborough is not entitled to the latter since it cannot sustain human habitation. And both parties still enjoy traditional fishing rights at the shoal as awarded by the tribunal, though Beijing has never recognized that and continues to harass Filipino fishers. The baselines could complicate this matter, as UNCLOS only allows traditional fishing rights in the territorial sea, not internal waters. Having declared everything inside the new baselines to be internal waters, China might grow even more aggressive in driving Filipinos out of the lagoon of Scarborough, forcing them to fish farther from the reef.
Q3: How have other claimants and the international community reacted?
A3: The U.S. Department of State on November 8 publicly supported the new Philippine maritime laws and called for other claimants to follow Manila’s lead in conforming their claims to UNCLOS and the 2016 arbitration ruling. On November 14, Malaysia sent a note protesting the laws due to their reference to the Philippines’ dormant claim to Sabah. Once the Philippines publishes a forthcoming map of its maritime zones, including from claimed features in the Spratlys, Vietnam will likely issue a statement opposing those claims and reiterating its own, which should be read as a symbolic rather than substantive protest.
The other claimants and outside parties will likely remain silent on China’s baselines around Scarborough Shoal, as sovereignty is disputed only by the Philippines, and the baselines do not harm freedom of navigation in the way that the Paracel baselines do.
Q4: Where do the disputes go from here?
A4: The new maritime laws are the latest step the Philippines has taken to bring its claims into accordance with UNCLOS. Such clarifications add to the contrast between the nature of the Philippines’ claims and those of China, imposing more reputational costs on Beijing for remaining outside the bounds of international law. The Philippines likely also hopes it will lead to opportunities for Southeast Asian claimants to strike agreements on their overlapping maritime claims and present a united front against China’s extralegal position.
This approach has already had some modest success. In July, the Philippines submitted its extended continental shelf claim in the South China Sea to the UN Commission on the Limits of the Continental Shelf, joining Malaysia and Vietnam, which had done so in stages between 2009 and 2024. In response, Hanoi said it was interested in entering negotiations with Manila on the area of overlap between their continental shelf claims.
But there are obstacles that will likely prevent all Southeast Asian claimants from coming to a unified position on maritime claims. The Sabah issue is likely to sink any efforts at maritime boundary delimitation between Malaysia and the Philippines, as Kuala Lumpur has long maintained its stance to be absolute and nonnegotiable while Manila, despite several attempts, has been unable to relinquish its claim due to domestic political factors.
Insomuch as clarification of claims in the South China Sea is a prerequisite to delimitation and management, the new Philippine laws are a welcome step in the right direction. But, in the near term, they will do little to reduce tensions in disputed waters. China has shown no interest in compromising on its claim to rights across all the waters encompassed by its nine-dash line, which remains irreconcilable with UNCLOS. This means that negotiations on a Code of Conduct for the South China Sea are liable to remain deadlocked while the claimants continue to jockey with coast guard, navy, and militia boats to assert their claims on the water—with a significant risk of escalation.
Harrison Prétat is deputy director and fellow with the Asia Maritime Transparency Initiative at the Center for Strategic and International Studies (CSIS) in Washington, D.C. Gregory B. Poling is a senior fellow and director for the Southeast Asia Program and the Asia Maritime Transparency Initiative at CSIS.
