Written by Jonathan Alberts

Introduction

The South China Sea remains one of the most strategically significant and hotly contested maritime regions in the world, with nearly one‑third of global trade passing through its waters.¹See United Nations Convention on the Law of the Sea, 1833 U.N.T.S. 397, arts. 1–16 (entered into force Nov. 16, 1994) [hereinafter UNCLOS], https://www.un.org/depts/los/convention_agreements/texts/unclos/unclos_e.pdf. China’s assertion of sovereignty over almost ninety percent of the area through its self‑declared “Nine‑Dash Line” (“NDL”) directly conflicts with the maritime rights afforded to other coastal states under the United Nations Convention on the Law of the Sea (“UNCLOS”).²See The Republic of the Philippines v. The People’s Republic of China, P.C.A. Case No. 2013-19, Award para. 1203 (Perm. Ct. Arb. July 12, 2016) [hereinafter PCA]. The Philippines sought arbitration under Annex VII of UNCLOS, resulting in a landmark 2016 award from the Permanent Court of Arbitration (“PCA”), which rejected China’s sweeping claims.³Id. at paras. 1191–1200. China’s decision not to implement the ruling underscores a notable gap in the enforcement mechanisms of the UNCLOS framework.⁴See generally Rex Lien Doan, The Conflict of Laws in the South China Sea and Its Threats to the Indo-Pacific Rules-Based Order, 55 Loy. 2 (2024), https://lawecommons.luc.edu/cgi/viewcontent.cgi?article=2869&context=luclj (explaining that China’s expansive nine-dash line claim and its rejection of the 2016 PCA Arbitration Award constitute an attempt to reshape regional legal norms by subordinating international law to domestic political imperatives). China’s noncompliance highlights UNCLOS’s structural weaknesses and explores potential reforms to strengthen the enforcement of international maritime law. 

Background

UNCLOS provides the foundational legal framework for maritime governance, establishing territorial seas, exclusive economic zones (“EEZs”), and continental shelf rights.⁵UNCLOS, supra note 1, art. 35; see also Tara Davenport, The 1982 UN Convention on the Law of the Sea: Maritime Zones and Maritime Boundary Delimitation, Nat’l Univ. of Sing. (Nov. 4, 2016) https://cil.nus.edu.sg/wp-content/uploads/2016/10/Day-1-Introduction-to-UNCLOS-by-Tara-Davenport.pdf. It also creates a compulsory dispute‑resolution mechanism through Articles 286–287 and Annex VII, requiring states to submit to binding arbitration when disputes arise.⁶Id. arts. 286–287. However, while UNCLOS articulates binding legal obligations, it lacks coercive mechanisms to ensure that states comply with tribunal rulings.⁷See Doan, supra note 4, at 32, 33. This structural limitation becomes especially evident in cases involving powerful states, whose geopolitical interests may outweigh legal obligations. 

The Philippines initiated arbitration in 2013 to challenge China’s expansive maritime claims under UNCLOS Annex VII.⁸See generally PCA, supra note 2 (claiming that China unlawfully challenged the role of historical rights, maritime entitlements, and the UNCLOS through actions of land reclamation, militarization, and area denial capabilities). The 2016 award ruled that China’s claimed historic rights within the NDL were incompatible with UNCLOS and held no legal validity.⁹PCA, supra note 2, at para. 207. The award further determined that several features occupied by China were either rocks or low‑tide elevations incapable of generating EEZs, directly undermining the basis of China’s extensive maritime claims.¹⁰ Id. at para. 1205(B)(7)(a)–1205(B)(7)(c). Moreover, the tribunal held that China had violated the Philippines’ sovereign rights by interfering with fishing and petroleum exploration within the Philippine EEZ.¹¹Id. at paras. 1205(B)(9), 1205(B)(10)(c), 1205(B)(14)(c). China’s categorical refusal to recognize or comply with the award exposed UNCLOS’s inability to enforce binding legal judgments on unwilling states.¹²See Doan, supra note 4, at 32. 

Analysis

The UNCLOS regime depends heavily on voluntary state compliance, as it lacks any standing international body responsible for enforcing arbitral awards or sanctioning violations.¹³See UNCLOS, supra note 1, art. 296 (stating that decisions of courts and tribunals “[. . .] shall be final and shall be complied with by all the parties [. . .]” while no article provides a method to enforce that compliance).   As a result, UNCLOS rulings risk becoming symbolic rather than practical when confronted with geopolitical resistance. Powerful states such as China can simply disregard binding decisions without fear of institutional consequences, reducing legal obligations to political preferences.¹⁴See Doan, supra note 4, at 36.  China’s continued militarization of disputed features following the 2016 PCA ruling demonstrates the ease with which noncompliance can undermine the rule of law at sea.¹⁵See China approves nature reserve at disputed South China Sea shoal claimed by the Philippines, AP News (Sep. 10, 2025) https://apnews.com/article/china-philippines-scarborough-shoal-nature-reserve-6131d2bd2bc54c53546481609c7ac67c.

In the absence of coercive enforcement tools, states have turned to political measures, most notably Freedom of Navigation Operations (“FONOPs”), to contest China’s maritime claims.¹⁶See generally Sam Bateman, Freedom of Navigation in the South China Sea, Broader Horizons (Nov. 2015), https://www.rsis.edu.sg/wp-content/uploads/2015/12/301115_NL_BH_Nov_15.pdf (explaining FONOPs as the insertion of naval ships or aircraft carriers non-threateningly entering areas of contestation and exercising rights which are allowable under international law). While these operations reinforce principles of open navigation and challenge excessive maritime claims, they do not constitute legal enforcement and depend on geopolitical power rather than judicial authority.¹⁷Id. at 4. Scholars argue that when compliance with international law depends primarily on political rather than legal mechanisms, the legitimacy of the international system weakens.¹⁸See generally Harold Koh, Review Essay, Why Do Nations Obey International Law?; The New Sovereignty: Compliance with International Regulatory Agreements; Fairness in International Law and Institutions, 106 Yale L.J. 2599 (1997) (examining how states comply with international legal norms not merely out of coercion but through mechanisms of cooperation, institutional design, and perceptions of fairness, highlighting the role of both regulatory frameworks and legitimacy in promoting adherence to international law).  The South China Sea reflects this dynamic: the PCA’s binding legal ruling has been overshadowed by strategic maneuvering and naval power projection.¹⁹See Bateman, supra note 16. 

Critics argue that UNCLOS’s lack of coercive enforcement mechanisms is intentional, reflecting a desire to preserve state sovereignty and maintain broad participation in the treaty.²⁰See generally Aly Rashid, Maintaining Maritime Peace: Growing Obstacles to the UN Convention on the Laws of the Sea, DLP Forum (Oct. 18, 2023), https://www.dlpforum.org/2023/10/18/maritime-peace-obstacles-un-convention-laws-sea (stating that enforcement would require politically difficult reforms, including approval from major powers and Security Council members, underscoring that the UNCLOS’s limited coercive mechanisms are largely a product of the need to avoid alienating powerful states and preserve widespread adherence). According to this view, diplomatic and reputational pressure remains the most appropriate means of encouraging compliance without undermining state consent or escalating conflict. However, while these concerns highlight the consensual nature of international law, they risk rendering UNCLOS ineffective when states openly defy binding rulings without consequence.²¹ Id. 

Conclusion

The 2016 South China Sea arbitration reveals a central vulnerability in the UNCLOS system: its inability to enforce compliance with binding legal decisions when confronted with geopolitical resistance.²²Compare PCA, supra note 2, and UNCLOS, supra note 13, with AP News supra note 15.  China’s rejection of the PCA ruling demonstrates how powerful states can undermine the authority of international law, weakening global confidence in maritime governance.²³See Doan, supra note 4, at 32, 33.  To preserve UNCLOS’s legitimacy, the international community must explore reforms that enhance compliance, whether through regional cooperation, institutional innovation, or incentive‑based frameworks.