Additionally, the Philippines has repeatedly tried to internationalize the dispute by inviting in external actors to constrain China and thereby increase the Philippines’s own leverage. For example, the Philippines has broadened and deepened its relationship with Beijing’s other rivals such as Japan, South Korea, and Australia. Manila has also tried to use the Sea’s hydrocarbons to entice countries like Russia and India into the region. And in its efforts to enlist outside allies, Manila has not forgotten its relationship with the United States – the two countries recently agreed to a new security accord that grants American military forces access to local bases for maritime and humanitarian operations. Finally, closer to home, the Philippines has been working to increase ties between the members of ASEAN in order to form a united front against Beijing.

China Pushes Back

But the Philippines has had only mixed success in executing the first two elements of its proactive strategy, namely, changing the facts on the ground and internationalizing the dispute. On the positive side of the ledger, the Philippines has successfully provoked China while crafting a regional narrative that portrays Beijing as the bully and the Philippines as a weak but feisty victim. In part due to China’s pushback against the Philippines, regional public opinion has swung sharply against China. The international community has become more and more involved in the dispute even as the Philippines and other claimants increasingly band together for protection against China.

But although Beijing is losing control of the public narrative, China has nevertheless effectively maintained the upper hand over much of the South China Sea itself. In crude terms, the Philippines’s strategy depends on forcing China to choose between losing the South China Sea and losing the region as a whole. Yet China has thus far evaded this stark choice by relying on a strategy that responds in a tit-for-tat fashion against Philippine provocations while deterring further escalation. Beijing’s minatory strategy has not won it many friends in the region, but it has not been sufficiently egregious to staunch—much less slow—regional trade. So while tensions continue to mount, China has not yet been pushed to the brink, as the Philippine strategy requires.

Worse, the Philippine strategy has come at significant cost. China has managed to score some spectacular successes, best exemplified by Scarborough Shoal. Although Manila intended to intimidate China out of the Shoal, the strategy backfired – Beijing effectively punted the Philippines out, and has since consolidated control over the area.

In part, the Philippines has faltered in its campaign because it has been fighting on the wrong battlefields. As part of the first two elements of its strategy, Manila tried (1) to change the on-the-ground reality in the South China Sea and (2) to internationalize the dispute. Yet in both arenas, China holds a comparative advantage. As described previously, China has maritime enforcement assets that easily dwarf those owned by the Philippines. Against this greater physical strength, the Philippines has relatively little leverage to change material realities. Similarly, China has greater weight than the Philippines in the international community thanks to its extensive trade relationships. States generally listen when Beijing warns them that any involvement in the South China Sea dispute could be costly for their investments in China. So even if some actors are becoming increasingly wary of China’s behavior, none has yet mustered the courage to put its money where its mouth is and to decrease its trade with the world’s second largest economy. Indeed, several international oil companies have ultimately decided against investing in the South China Sea after hearing that it could adversely affect their Chinese projects.

For its strategy to succeed, then, the Philippines needs to throw down the gauntlet in an arena where it has a comparative advantage over China and where China has difficulty leveraging its relative strength. For that reason, Manila has increasingly prioritized the third element of its strategy: international law.

The Mouse That Roared: A New Emphasis on International Law

All states are (generally) considered equal in the eyes of the law. International law can therefore be used to negate China’s material advantages in strength and reduce it to the same level as the Philippines. Accordingly, since 2011 Manila has relied more and more on international law as a weapon for prosecuting its claims. Of course, all of the South China Sea claimants frequently justify their claims through the language of international law. But the Philippines has done more than merely defend its claims through international law; it has also applied international law to contest China’s own claims in a variety of different arenas.

The opening shot was fired on Apr. 5, 2011. That day, Manila filed a note verbale with the United Nations protesting China’s nine-dash line as “hav[ing] no basis under international law.” The note was peculiarly timed; it responded to a previous pair of notes filed by China almost two years earlier, on May 7, 2009. When China had originally filed its notes, it had elicited a flurry of response notes from other nations over the following few months. But the Philippines stayed silent for two years before it decided to resurrect the issue unilaterally by filing its own note. Manila was interested in more than diplomatic formality; it chose to puncture that long stretch of inactivity in order to put Beijing on the defensive.

Since then, the Philippines has ramped up its international law offensive. Most significantly, Manila decided to take its case to a neutral arbiter in the wake of the Scarborough Shoal fiasco. On January 22, 2013, Manila took the bold step of launching an arbitration process under the auspices of the U.N. Convention on the Law of the Sea (UNCLOS). In its case, the Philippines is primarily making three claims: first, that China’s nine-dash line is unlawful under the Convention; second, that many maritime features claimed by China do not generate a 200-nautical mile exclusive economic zone (EEZ) as Beijing asserts; and third, that China has repeatedly violated the Philippine’s rights under the Convention.

Unsurprisingly, Beijing has rejected the Philippines’s claims and refused to participate in the case. Yet according to Article 9 of Annex VII to the UNCLOS, “[a]bsence of a party or failure of a party to defend its case shall not constitute a bar to the proceedings.” While it is uncertain what effect China’s absence will have on the tribunal’s jurisdiction, the arbitration seems to be going the Philippines’s way for now. Despite Beijing’s nonparticipation, the five members of the tribunal were chosen in April 2013. They issued their first procedural order on August 27, setting a deadline for the Philippines to submit its memorial. On March 30, 2014, the Philippines did so.

In some respects, the Philippines’s focus on international law seems strange given the weakness of its own territorial claims. But the Philippines has been able to mask the weakness of its own claims by going on the offensive. It has set the terms of its UNCLOS case, choosing to focus less on its own tenuous legal position and more on the flaws in China’s expansive claims. In particular, the Philippines has a weak claim to the territory of the Spratly Islands when compared to China. But its case is focused not on who owns the islands—indeed, the tribunal does not have jurisdiction to resolve that question—but rather on maritime legal issues such as which insular features of the South China Sea are entitled to an EEZ under UNCLOS. And because China has refused to participate in the arbitration, Beijing has forfeited an opportunity to stress its own perspective and draw attention to Manila’s vulnerabilities.

Despite its formal abstention from the proceedings, though, China has nevertheless been frantically trying to stop the case. In the year and a half since the Philippines filed it, Beijing has tried alternatively to cajole and menace Manila into ending the arbitration process. The Philippines has rebuffed these attempts, sometimes publicly (to Beijing’s considerable embarrassment). China has also tried to turn the other members of ASEAN against the island nation, but has been met with polite refusals from that quarter as well.

At some level, China’s reaction seems overwrought. Even if the tribunal reaches the merits and decides against Beijing, so what? But China values being perceived as a rule-bound international actor because that perception has tangible benefits. As China grows more powerful, it must avoid appearing as a rogue revanchist state out to destabilize the extant world order. As it is, China’s neighbors are already skittish about trading with—and thereby strengthening—the large nation. Beijing cannot afford to give them any more cause for concern.

Therefore, the Philippine case has coercive potential precisely because it has become a barometer of China’s trajectory and even its identity. When pressured, will Beijing respect international norms? Or will it accede to the Thucydidian logic that “the strong do what they can and the weak suffer what they must”?

Manila has found a weak spot, and it intends to exploit China’s discomfort for at least a little while longer. And if its arbitration gambit succeeds, then the Philippines will likely continue to emphasize international law in its pro-active strategy.