July 17, 2026
JAKARTA – ASEAN member states should immediately challenge China’s declaration that there is no high seas in the South China Sea, given its claim that the entire sea falls within its territorial waters under the so-called ten-dash line, a retired Philippine judge said.
China ratified the Biodiversity Beyond National Jurisdiction (BBNJ) Agreement, also called the High Seas Treaty, on Dec. 22, 2025, and formally declared that there are no high seas in the South China Sea and that the High Seas Treaty does not apply there, retired Justice Antonio Carpio said on Monday.
“China claims that the waters within the 10-dash line are China’s jurisdictional waters and the treaty applies only to waters beyond national jurisdiction,” he said on Monday.
“Therefore, China is saying formally that there are no high seas in the South China Sea because waters within the 10-dash line are our jurisdictional waters.”
Speaking at the Commemorative Conference of the 10th Anniversary of the South China Sea Arbitral Award held in Jakarta on Monday and Tuesday, Carpio said China’s formal declaration prevented the existence of the high seas in South China Sea as well as Exclusive Economic Zones (EEZ) of other states within the waters enclosed by the 10-dash line.
China maintains that everything within the 10-dash line is its jurisdictional waters so it cannot be the EEZ of other states, a claim which has been quashed by the arbitral award.
“Now, under the doctrine of acquiescence in international law, unless the Philippines, Vietnam, Malaysia, Brunei, Indonesia protest this formally, they are deemed to have acquiesced to China’s claim that there are no high seas in the South China Sea and everything within the 10-dash line are China’s jurisdictional waters,” he said.
“There are serious adverse consequences of these other coastal states in the South China Sea because first their fishermen can no longer fish in the high seas of the South China Sea.”
He said doing nothing would only mean coastal countries agreed with China’s claim that there are no high seas in the South China Sea.
Carpio added that China’s coastline was about 800 nautical miles away from the Philippines and therefore there was no overlap EEZ in both countries, meaning there are high seas in between.
The former associate justice of the Philippine Supreme Court said the high seas of the South China Sea comprise about a fifth of the entire sea, with freedoms of navigation, overflight, and fishing for all countries. This means even a landlocked country such as Laos can fish in the high seas of the South China Sea if it wants to, he added.
Carpio said the solution to the claim was simple.
“We must all protest. The moment we protest, then China cannot say that we acquiesced. China cannot invoke the doctrine of acquiescence and to protest doesn’t cost us anything,” he said.
“We just present a paper to the UN Secretary General and that bars immediately China from saying we acquiesced and we are bound by the doctrine of acquiescence under international. “So, we should all protest and it doesn’t cost us anything. We have everything to gain and nothing to lose to protest.”
Biggest beneficiary
In addition to quashing China’s claim of historic rights within the then nine-dash line, the arbitration also ruled that for a maritime feature to qualify as an island with a 200-nautical-mile EEZ, it must be able to naturally sustain human habitation or economic activity on its own. Rocks, therefore, are entitled only to a 12-nautical-mile territorial sea, while features submerged at high tide generate no territorial sea, EEZ, or continental shelf of their own.
This ruling allows China to be the biggest beneficiary from the 2012 arbitral award because China has the world’s largest fishing fleet, Carpio said.
“This means that many of the islands in the Pacific or in the Caribbean Sea or in other parts of the world which are tiny, which cannot sustain human habitation, can no longer claim a 200-nautical-mile exclusive economic zone,” he said.
“So, the high seas have actually been expanded tremendously by this ruling and of course the number one beneficiary is China, because China has the largest fishing fleet in the world.”
He said that islands which cannot support human habitation only have a territorial sea of 1,500 square kilometers when compared to 431,000 square kilometers of EEZ if an island can support human habitation.