MANILA - The Philippines "dropped the ball" on its landmark arbitration victory and should lodge a similar complaint if China ends up militarizing Scarborough Shoal, Senior Associate Justice Antonio Carpio said Wednesday.
Carpio warned that Beijing would agree on a code of conduct only after it had seized control of the South China Sea "for economic and military purposes."
Building military structures on Scarborough Shoal is said to be the last piece in China's so-called "strategic triangle" plan to control the vital waterway.
Defense Secretary Delfin Lorenzana earlier said China had planned reclamation activities on the shoal but was prevented by the United States last year.
"The Philippines should now prepare to file another arbitration case before the (arbitral) tribunal on the ground that any reclamation of Scarborough Shoal will destroy the shoal as a traditional fishing ground of Filipino fishermen as ruled by the arbitral tribunal," Carpio told a forum in Makati City.
Carpio said the government should also consider an extended continental shelf claim on the West Philippine Sea off the coast of Luzon, similar to the case it won for Benham Rise in 2012.
The UN Commission on the Limits of the Continental Shelf would reject a possible opposition based on China's nine-dash line claim because it was already invalidated by the Hague-based Permanent Court of Arbitration, the justice said.
"China will be placed in a dilemma on how to oppose (the claim)," he said.
Beijing has continued its military build-up in the disputed areas, installing missiles and communications systems on reclaimed islands in the Spratlys.
Last year, the Hague-based court clarified maritime entitlements in the disputed waters and rejected the basis of Beijing's expansive claims over the South China Sea.
But President Rodrigo Duterte later announced he was "setting aside" the ruling, as he sought billions of dollars in aid and investments from China.
Carpio said the Philippines "escaped a self-inflicted colossal disaster by the skin of our teeth" when the foreign affairs department later clarified Manila was not abandoning the ruling.
He said Manila would not be courting war if it pushes to enforce the ruling because it would not mean "forcibly evicting China" from the islands and features it now occupies.
"The option for the Philippines is not either to talk to China or go to war with China," he said.
"This is a false option and shows a dismal lack of understanding of international law and international relations."
Carpio noted Beijing was also not looking at the war option because it would give Washington, a treaty ally of the Philippines, an "excuse to intervene" in the dispute.
A "real and practical option" is to sit down with China on a sea code that could help manage disputes in the South China Sea, preservation of the marine environment, and access to Filipino fishermen, he said.
Carpio said the Philippines could also enter into sea boundary deals with Vietnam and Malaysia.
"There are many ways of enforcing the ruling. It's not a question of going to war with China," he said.