Carpio urges PH gov't to file twin arbitration cases against China over sea dispute

Retired Supreme Court Senior Associate Justice Antonio Carpio is calling on the Philippine government to take urgent legal action against China by filing two separate arbitration cases over unresolved maritime and territorial disputes in the South China Sea.

Carpio said this in a recent public forum, organized by the National Youth Movement for the West Philippine Sea (NYMWPS) in celebration of the 9th anniversary of the victory of the Philippines at the Arbitral Tribunal.

He emphasized that the Philippines, alongside regional partners, should initiate international legal proceedings to challenge China’s maritime claims and clarify ownership of the disputed Spratly Islands.

Carpio warned that continued inaction would allow China, now boasting the world’s largest naval fleet by number of ships, to consolidate control through military advantage.

"I've been trying to convince the Philippine government to challenge China to submit the territorial dispute to arbitration because at least the UN Charter says that all disputes between or among states must be settled by peaceful means, by negotiation, mediation, and finally by arbitration," he said.

"We cannot allow this dispute to remain unresolved because, of course, there will be skirmishes in the sea, and uh, we should settle this dispute uh peacefully and by following the rule of law," he added.

First Case: Dispute Over Extended Continental Shelf

Carpio's first proposal focuses on the extended continental shelf (ECS) beyond the Philippines' exclusive economic zone (EEZ), a maritime area also claimed by Vietnam, Malaysia, and China.

In 2009, Vietnam and Malaysia jointly submitted a claim to the United Nations Commission on the Limits of the Continental Shelf (CLCS), which China opposed. 

The Philippines later filed its own ECS claim in 2010, also met with opposition.

Under the United Nations Convention on the Law of the Sea (UNCLOS), if any party objects, the CLCS cannot act on the claim, leaving arbitration or negotiation as the only options. 

Carpio said negotiations have stalled due to China’s hardline stance.

“Time is on China’s side,” Carpio warned. “The only solution is to submit the dispute to compulsory arbitration under UNCLOS. This is a low-hanging fruit.”

Carpio explained that under UNCLOS rules, the ECS would likely be equitably divided among states within 350 nautical miles of the area—namely the Philippines, Vietnam, and Malaysia—while China, whose Hainan coastline is more than 350 nautical miles away, would have no legal claim.

“If China bases its claims on the Nine-Dash or now Ten-Dash Line, the arbitral tribunal will again strike it down,” he said.

“This is a no-brainer. One of the claimant states can initiate the case, and the others will be drawn in. The tribunal will proceed even if some states refuse to join.”

Second Case: Territorial Dispute Over the Spratlys

Carpio’s second proposed arbitration targets the long-standing territorial dispute over the Spratly Islands, claimed in full or in part by five countries—China, Vietnam, the Philippines, Malaysia, and Brunei. 

While no international treaty currently compels arbitration on territorial claims, Carpio said the Philippines should challenge China to agree to arbitration or face international scrutiny.

“Unlike maritime disputes under UNCLOS, territorial disputes require voluntary consent by the parties,” Carpio noted. “But this is a very simple territorial dispute. Both China and the Philippines agree that Philippine territory is defined by three treaties—the 1898 Treaty of Paris, the 1900 Treaty of Washington, and the 1930 treaty with Britain.”

Carpio argued that China misinterprets these treaties, especially the 1900 Treaty of Washington, which amended the earlier Treaty of Paris to include islands of the Philippine archipelago outside the original boundary lines. This amendment, Carpio emphasized, includes the Spratly Islands and Scarborough Shoal.

“The Treaty of Washington says, Spain also cedes to the U.S. any and all islands belonging to the Philippine archipelago lying outside the Treaty of Paris lines,” Carpio stated. “This is very clear. China agrees on the legal basis but interprets it incorrectly. We should challenge China to arbitration. If they refuse, we must bring the case to the court of world opinion.”

He also cited the U.S. State Department’s 1938 confirmation that Scarborough Shoal belonged to the Philippines, as well as the 1875 Spanish “Carta General” map, later adopted by the Americans, which included the Spratlys as Philippine territory.

Carpio urged the Philippine government to immediately file the two arbitration cases and coordinate with Vietnam and Malaysia on the ECS dispute.

“The UN Charter requires that all disputes be settled peacefully through negotiation, mediation, and arbitration,” he said. “We must act now while international law is still on our side. Every year we delay, China’s military advantage grows.”

Carpio concluded by stressing the simplicity of the legal arguments and the urgency of the situation.

“These cases are winnable. The facts, the treaties, and the law are all clear. What we need now is political will.”