Retired Supreme Court Senior Associate Justice Antonio T. Carpio has called on the Philippine government to initiate a new international arbitration case to resolve the territorial dispute in the West Philippine Sea, particularly over the Kalayaan Island Group.
In a recent interview on One News, Carpio emphasized that the Philippines possesses strong historical and documentary evidence to support its claim of sovereignty.
Historical Maps as Legal Foundation
Carpio pointed to the 1734 Pedro Murillo Velarde map, the earliest official map of Philippine territory during the Spanish period, which already depicted the Spratlys—referred to at the time as Los Baos de Paragua, or the shoals of Palawan. He noted that this inclusion was reaffirmed in subsequent official maps issued in 1808 and 1875.
According to Carpio, no earlier maps from China, Vietnam, or Malaysia show a claim over the Spratlys. He added that China’s first map asserting ownership appeared only in 1947, after World War II.
He explained that the principle of res nullius—territory not claimed by any state—applies in this context, arguing that when the Philippines included the islands in its official maps in 1734, no other state had made a competing claim.
Arbitration as a Diplomatic Tool
Carpio urged the Department of Foreign Affairs (DFA), with support from the Office of the Solicitor General (OSG), to take the lead in pursuing arbitration. He drew parallels to the 2013 case filed under the United Nations Convention on the Law of the Sea (UNCLOS), which resulted in the 2016 arbitral ruling that invalidated China’s nine-dash line claim.
However, he clarified that while UNCLOS governs maritime disputes, a territorial dispute over sovereignty must be brought before the International Court of Justice (ICJ). Such proceedings would require the consent of both parties.
Carpio stressed that arbitration is part of diplomacy and should not be viewed as antagonistic. He noted that negotiation, mediation, and arbitration are established mechanisms under international law.
Political Will as the Deciding Factor
Ultimately, Carpio said, the decision to initiate arbitration rests with the President. He expressed confidence that the Philippines has sufficient historical documentation and treaty support to sustain its claim should the matter proceed to international adjudication.
The former magistrate reiterated that the country prevailed in the 2016 arbitral case despite doubts at the time and suggested that a similarly grounded legal strategy could once again affirm Philippine sovereignty under international law.