Will the Philippines File a Second South China Sea Arbitration Case?

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Will the Philippines File a Second South China Sea Arbitration Case?

The Philippines is exploring the possibility of bringing China to another international dispute settlement organ.

Will the Philippines File a Second South China Sea Arbitration Case?

Philippine troops salute the flag on Likas Island in the West Philippine (South China) Sea during a visit by Commander of the Western Command (WESCOM), Vice Admiral Alberto B Carlos PN, Sep. 22, 2023.

Credit: Western Command Armed Forces of the Philippines

In a press interview, Menardo Guevarra, the incumbent solicitor general of the Philippines, stated that Manila is conducting studies to assess the extent of environmental damage at Iroquois Reef in the South China Sea caused by Chinese vessels. He added that the Philippines is considering seeking legal action against China at an international court or arbitral tribunal. Iroquois Reef is an entirely submerged reef formation that is located at the southern end of Reed Bank and northeast of the Spratly Islands, an area that is thought to be rich in oil and gas.

This statement was made after a series of provocative actions by China in the South China Sea, where Beijing’s expansive claims overlap with the Philippines’ exclusive economic zone (EEZ). If the Marcos administration follows through with the case, it will be the second time the Philippines has brought China before an international court in matters relating to the South China Sea, where disputed maritime claims have turned the region into a flashpoint of global concern. 

What Happened in the First South China Sea Arbitration Case?

The 2016 South China Sea arbitration between China and the Philippines was a landmark case ruled by the Annex VII arbitral tribunal constituted under the 1982 United Nations Convention on the Law of the Sea (UNCLOS). The 479-page ruling of the Award was overwhelmingly favorable to the Philippines – the claimant in this case – and disregarded all arguments made by China, which chose not to participate in the proceeding. The findings of the Award shed light on several controversial issues in the South China Sea.

First and foremost, the Tribunal found that China’s claim to historic rights and resources within the nine-dashed line, encompassing 90 percent of the South China Sea, has no legal basis under international law.

Second, the Tribunal ruled that none of the features in the Spratly Islands satisfied the criteria for being classified as an island under UNCLOS and, as such, are not entitled to a 200 nautical mile EEZ and a continental shelf. This finding drastically limits the potential overlapping areas of dispute among the claimants in the South China Sea.

Third, the Tribunal found that China has violated its obligations under UNCLOS by interfering with the Philippines’ exercise of its sovereign rights over the living and non-living resources in its EEZ and continental shelf. One specific violation included the harassment of the Philippines’ survey ship by a Chinese patrol boat at the Reed Bank in 2011. Moreover, the Award stated that China violated its marine environmental protection obligations by causing severe harm to the coral reef environment with its land reclamation activities and harvesting of endangered species in certain parts of the South China Sea.

The Award is final, and the Philippines and China are legally bound by the ruling as parties to the dispute and signatories to UNCLOS. However, while the Philippines and many other countries welcomed the Award, China dismissed it as a “piece of waste paper” and increased provocative actions in the disputed area of the South China Sea after the ruling.

What Should the Philippines Consider for a Second Case?

Initiating an international proceeding against another state is not a small feat, especially against a country economically and militarily superior to your own. Besides the necessary political will, the Philippines should consider where they would file such a case, what issues to litigate, and when to start the proceeding.


When it comes to choosing a court for the Philippines to file its second case, the options are rather limited. Article 287 of UNCLOS provides four venues for a state party to settle disputes, namely the International Tribunal for the Law of the Sea (ITLOS), the International Court of Justice (ICJ), and arbitral tribunals under Annex VII and Annex VIII. However, the arbitral tribunal constituted under Annex VII is the default choice of states seeking the so-called “compulsory procedures entailing binding decisions” established under the Convention. If neither the Philippines nor China selected any other court as their preferred choice, Manila would have no choice but to file its case at the Annex VII arbitral tribunal.

This is by no means a bad choice. The Annex VII arbitral tribunal was also the venue that gave the ruling in the Philippines’ first case in 2016. As such, there would be a high chance that the tribunal would adopt the same approach and uphold the rulings in the first case, which were favorable to the Philippines’ position. 


Guevarra informed the press that the study underway that might lead to Manila filing the second case is not limited to the extent of environmental damage in Iroquois Reef in the Spratly Islands but also includes “other incidents and the overall situation in the West Philippine Sea.” The “other incidents” referred to here may include recent aggressive actions conducted by China in the South China Sea, including the introduction of a new ten-dashed line map, the militarization of Chinese-occupied features, laser shooting, water cannon blasting, and dangerous vessel maneuvering in the disputed area of the South China Sea.

The jurisdiction of the arbitral tribunal, however, has certain caveats. Article 297 of UNCLOS excludes cases concerning requests to conduct marine scientific research in the EEZ and those concerning the exercise of coastal states’ sovereign rights to exploit the living resources in their EEZ. Under Article 298, China has opted out of disputes concerning sea boundary delimitation and military activities or regarding the exercise of sovereign rights or jurisdiction of the coastal state over living resources in its EEZ. Consequently, these issues could not be litigated against China. 

Moreover, under the doctrine of res judicata, states may not re-litigate issues that have already been decided in a judgment or award by a court of law.   

As such, the Marcos administration should carefully consider which issue to litigate in its second case. Ideally, they should avoid issues that fall outside the scope of UNCLOS and the Tribunal’s jurisdiction, such as sovereignty over the features in the South China Sea or those that have already been settled in its first South China Sea case, including the illegal nine (now ten)-dashed line or China’s violation of marine environment protection obligations under the Convention with its land reclamation activities. 

Instead, the Philippines could formulate its claims to challenge recent aggravated actions by China, including its mobilization of hundreds of maritime militia vessels and harassment of other foreign vessels in the South China Sea. The decision of the arbitral tribunal on this issue would shed light on how to view China’s so-called gray zone tactics in the South China Sea under international law.


Any dispute involving the South China Sea is both legally and politically difficult. Moreover, international disputes take a long time to resolve, as evidenced in the first case, which took the arbitral tribunal more than three years to render its judgment. It would be in the interest of the Philippines to have the proceeding fall entirely within President Ferdinand Marcos Jr.’s term of office, which is set to expire on June 30, 2028. In this way, Manila can follow through with the litigation process and avoid a potential change of stance in the subsequent administration. With the previous award, a change in government saw the incoming Duterte administration largely ignore the case, which had been filed by its predecessor.

At this stage, it is still uncertain whether Manila will once again bring China before an international court or arbitral tribunal and what issues will form its core claims.

What is almost certain is that similar to the first South China Sea arbitration case, China will likely refuse to participate in the proceedings and will boycott the award if it is unfavorable to them.

Even still, UNCLOS, as the Constitution of the Ocean, remains a relevant legal instrument that provides venues for “compulsory procedures entailing binding decisions” to peacefully settle international disputes. A second decision by an international court or arbitral tribunal could shed light on important issues of the Convention and direct the claimants to bring their conduct into conformity with the international law of the sea.

In the meantime, the international community awaits the decision of the Marcos administration.