The Two Legal Orders Competing for the South China Sea

On July 12, fourteen nations — including the United States, Japan, the Philippines, the United Kingdom, and the European Union — issued a joint statement declaring the 2016 South China Sea arbitral ruling "final, legally binding, and definitive" and asserting that China's historic-rights claims have "no legal basis" under the UN Convention on the Law of the Sea ^[1]. The next day, Beijing summoned Japan's envoy to protest Tokyo's invocation of the ruling — and expanded the complaint to include Taiwan, chemical weapons, and ethnic policy, signaling it now treats the legal-normative front as part of a broader containment strategy ^[2]. The two events, compressed into a single weekend, are not an isolated flare-up. They are the latest collision between two legal architectures that have been assembling, layer by layer, since April — and that now define the South China Sea contest as clearly as any warship or reef. On one side, a multilateral coalition is converging on UNCLOS as its operating system. The April 7 joint statement by the US and 13 allies explicitly cited the 2016 Hague ruling and declared China's expansive claims have "no legal basis" ^[3]. The July 12 statement widened the coalition to fourteen and sharpened the language. Japan's Foreign Minister Motegi framed China's refusal to accept the ruling as something that "undermines the international rule of law" — a test case for the global legal order, not a regional territorial spat ^[1]. But the architecture is not just diplomatic statements. The Philippines now cites UNCLOS consent requirements as the operational basis for coast guard challenges. When Chinese research vessel Xiang Yang Hong 33 and 41 maritime militia vessels appeared near the Philippines in May, the coast guard made the legal basis explicit.

The Philippines has not granted such consent to the (People's Republic of China) for any (marine scientific research) activities in these waters. — Philippine Coast Guard

At Scarborough Shoal, the Philippine military linked its preventive enforcement directly to the 2016 ruling's findings on artificial island construction — military chief Brawner warned against allowing "a small structure" to grow into "an artificial island," as happened in the Spratlys ^[4]. The Philippines commemorated the ruling's tenth anniversary by calling it a "lighthouse" and "unshakable permanent anchor" for the rules-based order, and demanded that any future South China Sea Code of Conduct be legally binding and anchored on the award ^[5]. The legal front is expanding geographically and institutionally. Japan and the Philippines launched formal EEZ delimitation talks in Tokyo on June 4 — two US allies using UNCLOS-style bilateral boundary-setting as a deliberate legal counter to China's claims ^[6]. Cambodia initiated UNCLOS compulsory conciliation against Thailand over a $300 billion Gulf of Thailand dispute, with Hun Manet framing it as protecting sovereignty "in accordance with international law" ^[7]. Thailand's navy chief, after withdrawing from the 2001 MoU with Cambodia, explicitly cited UNCLOS as the framework for future boundary delimitation ^[8]. Taiwan's Coast Guard — excluded from most multilateral forums — invoked EEZ jurisdiction under international law to repel Chinese research vessels ^[9]. And non-claimant NATO members are now conducting freedom-of-navigation patrols: the Dutch frigate HNLMS De Ruyter was expelled from the Paracels by Chinese forces during a Pacific Archer mission that included drills with Philippine forces ^[10]. Even New Zealand's P-8A patrols, operating from Kadena Air Base in Japan, drew Chinese protests — friction that followed a March 2026 joint statement by New Zealand and Australia criticizing Chinese behavior in the South China Sea ^[11]. On the other side, China is building a mirror-image legal counter-infrastructure. Its most ambitious piece is a draft public-interest litigation law, now in its second reading before the NPC Standing Committee, that would empower procuratorial agencies to initiate litigation against foreign individuals and organizations that infringe Chinese interests — a domestic legal mechanism to target overseas entities ^[12]. In parallel, Chinese academics are advancing sovereignty claims over Philippine territory: Jinan University scholars claimed Batanes province belongs to China as a "natural geographical extension" of Taiwan, which Stanford's SeaLight project identified as a lawfare strategy to justify coast guard patrols in the Bashi Channel ^[13]. Beijing's approach to UNCLOS is selective. When Japan and the Philippines launched EEZ delimitation talks, China's Foreign Ministry invoked UNCLOS's delimitation provisions to declare the talks "illegal" because Beijing was not a party ^[14]. Yet when the 2016 UNCLOS arbitration went against it, Beijing's position was different.

The award will not alter the historical and factual basis for China’s sovereignty over the islands of the South China Sea and their adjacent waters. — Government of China

China's Taiwan Affairs Office framed coast guard patrols as a direct response to the Japan-Philippines talks, calling them "reasonable, lawful, legitimate, and necessary" ^[15]. And Beijing's Defense Ministry explicitly warned the Philippines to "stop counting on external forces to stir up troubles at sea, since such a scheme will prove self-defeating and fruitless" — confirming the multilateralization strategy is noticed and opposed at the highest levels ^[16]. The fault line runs through ASEAN itself. The Philippines, Cambodia, and Thailand are all deploying UNCLOS mechanisms — but Malaysia's Anwar Ibrahim is pushing in the opposite direction.

The Code of Conduct with China, together with our Asean partners, is important to secure and resolve this problem without interference from other forces. — Datuk Seri Anwar Ibrahim

Cambodia embodies the contradiction: it pursues UNCLOS compulsory conciliation against Thailand while simultaneously upgrading its security coordination with China from "2+2" to "3+3" ^[17] and establishing a formal security partnership that Xi Jinping described as a "model for ties with neighboring countries" ^[18]. No ASEAN-wide statement has endorsed the 2016 ruling. The multilateral legal front is a coalition of willing states, not a unified regional position. China is working to keep it that way. Wang Yi's April tour of Cambodia, Thailand, and Myanmar was a deliberate bilateral counter-offensive — offering to mediate the Cambodia-Thailand border conflict, pledging support for Myanmar's sovereignty, and securing Thailand's prime minister's affirmation that "Thailand and China are one family" ^[19]. The June security pact with Cambodia consolidated Beijing's key ASEAN ally — the state that has historically blocked ASEAN consensus on South China Sea statements ^[18]. One architecture is operational and expanding: the multilateral UNCLOS front adds new layers with each joint statement, coast guard challenge, and delimitation talk. The other is still being assembled — China's public-interest litigation law remains in its second reading ^[12], its academic claims are being tested, and its bilateral diplomacy is a holding action rather than a finished structure. Beijing holds leverage and security partnerships with individual ASEAN states that give it the means to prevent the regional consensus a unified legal front would require ^[19][18]. The contest's trajectory hinges on which legal architecture ASEAN ultimately chooses to live inside — and for now, the region is living in both at once.