How did the Philippines use international arbitration in its dispute with China over Scarborough Shoal?

In 2013, the Philippines initiated formal legal action against China by filing an arbitration case with the Permanent Court of Arbitration. This move was grounded in the 1982 United Nations Convention on the Law of the Sea (UNCLOS), a treaty to which both nations are signatories.1

The Philippines sought to challenge the lawfulness of China’s expansive maritime claims in the South China Sea, specifically regarding the Scarborough Shoal and China's actions to enforce those claims. In 2016, the arbitral tribunal issued a ruling that largely favored the Philippines, determining that China’s "nine-dash line" lacked legal basis and that its interference with Philippine fishing and maritime activities within the Philippines' exclusive economic zone was unlawful.12

China refused to participate in the proceedings, denied the tribunal's jurisdiction, and formally rejected the ruling as null and void. Despite the international legal decision, China continues to maintain a physical presence at the shoal, leading to ongoing tensions.12