Ten Years On: Inside the Legal Strategy of the South China Sea Arbitration

Atty. Florin Hilbay, former Solicitor General of the Philippines and principal agent in the arbitration under the United Nations Convention on the Law of the Sea (UNCLOS), delivered a public lecture titled "A Decade of Resolve: Reflections on the South China Sea Arbitral Award" at Auckland University of Technology (AUT) on October 14, 2026. Co-hosted by the AUT Philippine Studies Hub, the public event and a subsequent academic roundtable provided a rare, behind-the-scenes account of the legal strategy, technical hurdles, and geopolitical realities of the case.

The visit coincided with the 60th anniversary of diplomatic relations between the Philippines and New Zealand, a milestone marked by the recent elevation of the bilateral relationship to a Comprehensive Partnership.

Philippine Ambassador to New Zealand, H.E. Christianne Azucena stressed that the Award was not merely a decision concerning one bilateral dispute. It strengthened international understanding of the legal limits governing maritime claims and reinforced the importance of UNCLOS as a constitution for the oceans. Photo: (Carla Teng-Westergaard/AMC).

Opening the lecture, Philippine Ambassador to New Zealand H.E. Kira Christianne Azucena stressed that the Philippines did not initiate the arbitration out of a desire for confrontation.

"The Philippines did not bring the case to seek confrontation," Ambassador Azucena told the audience. "We brought it because disputes between states must be addressed peacefully, through law and through institutions."

She recalled the perspective of the late Foreign Affairs Secretary Albert del Rosario, who argued that Part XV of UNCLOS empowers states to engage on an equal legal footing, affirming that principles can prevail over power, law over force, and right over might.

Ambassador Azucena also highlighted that President Ferdinand Marcos Jr. has emphasised the deeply human dimension of the award. Quoting the President, she noted that the ruling is fundamentally about people, protecting Filipino fisherfolk who deserve to fish "in peace, in safety, and with the dignity to feed their own families," while safeguarding coastal communities whose survival depends on the ecological health of the oceans.

Demystifying the Law of the Sea: A 101 Primer

To explain the legal machinery behind the case, Hilbay provided what was essentially a Law of the Sea 101 primer. Under UNCLOS, often referred to as the "Constitution for the Oceans", maritime entitlements belong to land features based on geographic and physical characteristics, adhering to the principle that "the land dominates the sea".

A central achievement of the ruling was the tribunal's determination that expansive historic-rights claims, such as those associated with the "nine-dash line," have no legal basis under UNCLOS to the extent that they exceed the entitlements specified by the convention.

However, translating everyday geography into international law required strict categorisation under Article 121 of the treaty. Common geographical terms like shoal, reef, atoll, or cay do not carry legal weight; instead, UNCLOS divides features into distinct legal categories based on whether they stay above water at high tide and whether they can naturally sustain human life.

Low-tide elevations, features submerged at high tide and visible only at low tide, such as Mischief Reef or Second Thomas Shoal, generate no independent maritime zones. They possess no 12-nautical-mile territorial sea and no exclusive economic zone (EEZ), remaining part of the continental shelf of the coastal state on which they lie.

Arbitral Tribunal ruled that it had jurisdiction over the Philippines’ case against China because the dispute concerned the interpretation and application of UNCLOS, the United Nations Convention on the Law of the Sea, rather than sovereignty over islands. Photo: (Carla Teng-Westergaard/AMC).

High-tide features fall into two categories: rocks and fully entitled islands. Features that naturally remain above water at high tide, but cannot sustain human habitation or an economic life of their own, are classified as rocks under Article 121(3). Rocks generate a 12-nautical-mile territorial sea, but no 200-nautical-mile EEZ or continental shelf. Only fully entitled islands, naturally formed areas capable of sustaining human communities or independent economic activity, generate a full EEZ and continental shelf.

Crucially, the tribunal ruled that features must be evaluated based on their natural state. Under Article 60(8), artificial island building or environmental modification cannot legally upgrade a low-tide elevation into a rock, or a rock into a fully entitled island.

Furthermore, the tribunal clarified that non-archipelagic states cannot draw straight baselines around offshore island groups to claim them as a single collective unit.

Inheriting a Live Case

Hilbay assumed the role of Principal Agent in March 2015 after his predecessor, Francis Jardeleza, was appointed to the Supreme Court of the Philippines. He served through the oral hearings until late June 2016, concluding his tenure just weeks before the final award was rendered.

Hilbay reflected on the origins of the arbitration. Escalating tensions following a 2012 standoff at Scarborough Shoal, a rich traditional fishing ground within the Philippines' EEZ, served as the primary catalyst. Prior to the standoff, fishers from the Philippines, China, Vietnam, and Taiwan had fished those waters side by side.

When bilateral negotiations reached an impasse, the government of President Benigno Aquino III determined that arbitration was the only remaining option to clarify legal entitlements peacefully.

Atty. Florin Hilbay, the former Solicitor General of the Philippines and the country’s lead agent in the definitive case of the Republic of the Philippines v. People’s Republic of China. (Photo: Carla Teng-Westergaard/AMC).

Hilbay described managing a large and diverse legal team. External counsel, led by Paul Reichler of Washington firm Foley Hoag, included prominent international legal scholars such as Professors Bernard Oxman, Philippe Sands, and Alan Boyle. The team also drew on domestic scholars, Department of Foreign Affairs legal officers, and scientific experts.

Managing the various strategic perspectives required constant coordination. Furthermore, the tribunal's decision to bifurcate the proceedings, holding separate hearings on jurisdiction and the merits, presented major administrative and financial challenges. While bifurcation allowed the tribunal to rigorously evaluate its authority to hear the claims, it extended the timeline and increased litigation costs, requiring careful operational oversight.

The Strategic Challenge of Itu Aba

Among the most delicate legal questions faced by the Philippine team was the status of Itu Aba (also known as Taiping Island). Administered by Taiwan, Itu Aba is the largest naturally formed feature in the Spratly Islands, located approximately 200 nautical miles from the Philippine island of Palawan.

The legal dilemma was pivotal: if Itu Aba were classified as a fully entitled island under Article 121, it would generate its own 200-nautical-mile EEZ. That zone would overlap directly with the EEZ extending from Palawan, creating an overlapping maritime boundary dispute. Because China had filed a formal declaration under Article 298 in 2006 excluding boundary delimitations from compulsory arbitration, such a finding could have deprived the tribunal of jurisdiction over key Philippine claims in those waters.

Conversely, if Itu Aba were determined to be a rock, it would generate only a 12-nautical-mile territorial sea, leaving the surrounding waters within the undisputed EEZ of the Philippines.

The Philippine legal team presented scientific evidence showing that Itu Aba’s natural fresh water supply and soil could not sustain an independent human population or economic life without ongoing external support. The tribunal ultimately agreed, holding that "human habitation" requires a stable, natural community for whom the feature is home, and that an "economic life of its own" cannot rely predominantly on outside resources.

Applying this standard, the tribunal ruled that no feature in the Spratly Islands, including Itu Aba and Thitu (Pag-asa), qualifies as a fully entitled island, classifying them legally as rocks.

Although Pag-asa has a permanent Filipino population and a thriving community with a town hall, school, health clinic and internet access, the Tribunal did not consider modern living conditions alone sufficient to establish its legal status as an island capable of sustaining human habitation under UNCLOS Article 121(3).

First, the natural capacity test: The Tribunal assessed whether the feature could naturally sustain human habitation or economic life of its own, rather than relying on external support. Pag-asa depends heavily on supplies from mainland Palawan, including food, fuel and construction materials. Residents also receive government support, including housing and subsidies, to encourage settlement and maintain the Philippines’ presence.

Second, the historical capacity test: The feature’s legal status is assessed based on its natural condition, not solely on developments introduced by a government. Before permanent settlement, it was reportedly used mainly as a temporary stopover by fishermen. The Philippine government began establishing a civilian community there in the late 1970s, with further development in subsequent decades. Under this interpretation, building infrastructure and encouraging settlement cannot, by themselves, change a feature’s legal classification under UNCLOS.

In 2006, China excluded certain disputes from compulsory UNCLOS arbitration, but this was not a bilateral agreement with the Philippines to stop discussing island disputes. Photo: (Carla Teng-Westergaard/AMC).

A Far-Reaching Decision

The final Award of 12 July 2016 provided definitive legal rulings across the Philippines' core submissions. In addition to invalidating the nine-dash line historic-rights claim, the tribunal classified Scarborough Shoal, Johnson Reef, Cuarteron Reef, and Fiery Cross Reef as rocks. Mischief Reef and Second Thomas Shoal were designated low-tide elevations situated within the Philippine EEZ.

The tribunal found that unilateral activities interfering with fishing, petroleum exploration at Reed Bank, and land reclamation at Mischief Reef were incompatible with Philippine sovereign rights under UNCLOS. It affirmed Scarborough Shoal as a traditional fishing ground for small-scale fishers of multiple nationalities, ruling that restricting traditional fishing access violated international law.

Environmental protection formed another critical pillar of the decision. The tribunal ruled that large-scale reclamation activities had caused severe, permanent damage to fragile coral reef ecosystems, breaching state obligations under UNCLOS to protect and preserve marine environments.

The tribunal did not address sovereignty over land features or draw maritime boundaries. While China maintained its position of non-participation and non-acceptance, the ruling remains legally binding on both parties under international law.

The 2016 arbitral ruling was a landmark in international law, affirming that maritime rights in the South China Sea must be determined under UNCLOS, not solely through historical claims, although enforcement of the ruling remains a challenge. Photo: (Carla Teng-Westergaard/AMC).

Strategic Insights for Small and Maritime States

Reflecting on the 10th anniversary, academic conveners and legal experts in New Zealand highlighted the broader global implications of the award for small and medium-sized nations.

Professor Ceri Warnock of the AUT Law Faculty observed that the ruling reinforces the role of neutral institutions in resolving state-to-state disputes. She noted that UNCLOS took nearly a decade of global negotiation to craft, providing a binding legal framework to govern ocean space through consensus rather than raw power dynamics. "In addition to clarifying legal rights and responsibilities, decisions by international tribunals have a strong moral force," Professor Warnock said, adding that maritime nations like New Zealand rely on rules-based systems to protect freedom of navigation, marine sustainability, and regional stability.

Dr Sarah Lipura, co-leader of AUT Philippine Studies Hub, emphasised the importance of bringing direct accounts of international proceedings to public attention in New Zealand.

"The lecture offered a rare insider's perspective on the South China Sea Arbitration," Dr Lipura said. "It demonstrated that the Philippine experience offers not only a compelling case study but also an analytical lens through which to examine questions of international law, justice, power, sovereignty, and regional cooperation."

Dr Lipura added that the seminar paved the way for wider academic discussions hosted by the Hub, including the Reimagining the Global Filipino initiative, which seeks to bring Philippine perspectives into global policy debates.

Looking to the future, Hilbay noted that full implementation of major international legal decisions is a gradual process requiring sustained diplomatic engagement, coalition building, and educational outreach.

In Manila, standing study groups on maritime law continue to analyse developments, supported by the establishment of a dedicated Law of the Sea Academy within the Foreign Service Institute. Hilbay has also co-authored proposals calling for designated parts of the South China Sea to be declared a scientific commons, enabling marine scientists from all littoral states to collaborate on environmental preservation.

As Ambassador Azucena highlighted in her remarks, upholding international law is a shared global responsibility. A decade after the ruling, the 2016 arbitral award remains a cornerstone for maritime governance, demonstrating how small states can utilise international law to protect sovereign rights, preserve ocean resources, and support a peaceful, rules-based Indo-Pacific.

-Asia Media Centre