Ten years after the Permanent Court of Arbitration issued its award in the South China Sea arbitration, the ruling remains a cornerstone of sovereignty and international law in the Indo-Pacific, according to a retrospective published by the Indo-Pacific Defense Forum.

The tribunal, constituted under Annex VII of the United Nations Convention on the Law of the Sea (UNCLOS), handed down its award on 12 July 2016 in the case brought by the Philippines against China (PCA Case No. 2013-19). The Philippines filed the action in January 2013 after China asserted expansive claims within its so-called "nine-dash line" enclosing most of the South China Sea.

The tribunal's holdings were sweeping. It found that China's nine-dash line claims to historic rights over the waters of the South China Line exceeded the limits of what UNCLOS permits. It ruled that none of the Spratly Islands — the contested features at the heart of the dispute — generates an entitlement to an exclusive economic zone, classifying them as rocks at most under Article 121(3) of the Convention. The tribunal also held that China had violated the Philippines' sovereign rights in its exclusive economic zone through actions including interference with Philippine fishing and petroleum exploration, the construction of artificial islands, and failure to prevent Chinese fishermen from harvesting endangered species at Scarborough Shoal and in the Spratlys.

China rejected the ruling from the outset. Beijing declined to participate in the proceedings, refused to accept the award, and has continued to base its conduct on the nine-dash line the tribunal invalidated. The retrospective notes that this non-compliance has framed the decade since.

For practitioners, the award's continuing significance is doctrinal as much as geopolitical. The decision clarified the legal status of maritime features under Article 121(3), constraining claims that small, uninhabitable outcrops can generate vast maritime zones. It affirmed that historic rights claims must yield to the express limits of UNCLOS where the Convention applies. And it confirmed that an Annex VII tribunal may exercise jurisdiction over a dispute even when one party declines to appear, applying the presumption of opposability articulated in earlier jurisprudence.

The ruling has since become a reference point for states navigating competing claims in the region. Vietnam, Malaysia, Indonesia and other littoral states have invoked UNCLOS-based entitlements in the wake of the award, and the Philippines has relied on it diplomatically and operationally, pressing its lawful maritime zones against Chinese pressure.

The award's tenth anniversary comes amid continuing friction. The retrospective highlights that the conduct the tribunal condemned — island-building, interference with fishing and energy activities, and coercive encounters at sea — has persisted in the years since 2016. Nevertheless, the ruling stands as the definitive legal statement of the parties' respective rights and obligations in the South China Sea.

International lawyers regard the award as one of the most significant UNCLOS decisions to date. Its reasoning on the status of maritime features, the relationship between historic rights and the Convention, and the protection of the marine environment has been cited by governments, tribunals and scholars worldwide.

A decade on, the core point endures: the tribunal decided the dispute on the law, and the law has not moved. As the retrospective puts it, the award remains a cornerstone of sovereignty and international law in the South China Sea.

What follows for counsel advising states and commercial actors in the region is practical. Maritime entitlements in the South China Sea must be assessed on the tribunal's findings: no Spratly feature yields an exclusive economic zone, and nine-dash line claims carry no legal foundation under UNCLOS. Fisheries arrangements, seismic surveys and hydrocarbon licensing within the relevant exclusive economic zones remain exposed to the enforcement realities the award documented, whatever its formal authority.