US State Department study finds sweeping claims of PRC in South China Sea unlawful and without basis

"In the years since the Department of State published Limits in the Seas No. 143 in 2014 and the arbitral tribunal issued its decision in The South China Sea Arbitration in 2016, the PRC has advanced a new articulation of its maritime claims in the South China Sea. These expansive maritime claims are plainly inconsistent with international law as reflected in the Convention. 

First, the PRC’s claims to sovereignty over maritime features that do not meet the international law definition of an “island” and fall entirely beyond a lawful territorial sea are inconsistent with international law and not recognized by the United States and other States. This includes any claim to sovereignty over entirely submerged features like James Shoal, Vanguard Bank, and Macclesfield Bank. It also includes any claim to sovereignty over low-tide elevations, such as Mischief Reef and Second Thomas Shoal, which fall entirely beyond a lawful territorial sea entitlement and which are not subject to appropriation under international law. 

Second, the PRC’s baselines enclosing Xisha Qundao (Paracel Islands) and its asserted intention to establish baselines around other “island groups” in the South China Sea are also inconsistent with international law. None of the four islands or island groups that the PRC considers to comprise “Nanhai Zhudao” meet the geographic criteria for straight baselines reflected in Article 7 of the Convention. Notwithstanding the Convention’s comprehensive regulation of baselines, the PRC also attempts to argue that there is a separate body of customary international law, outside of the Convention, that justifies its straight baseline claims in the South China Sea. This PRC position, which is examined in the State Practice Supplement to this study, has no merit. The evidence compiled in the Supplement demonstrates conclusively that the requirements for the formation of customary international law relating to outlying island groups have not been met and, therefore, there are no customary international law rules that provide an alternative legal basis for continental States, such as China, to claim straight baselines around outlying island groups.

Third, the PRC’s claim to maritime zones “based on Nanhai Zhudao” is similarly inconsistent with international law. Any assertion of internal waters, territorial sea, exclusive economic zone, or continental shelf based on treating South China Sea island groups “as a whole” is not permitted by international law. Within its claimed maritime zones in the South China Sea, the PRC also makes numerous jurisdictional claims that are inconsistent with international law. These include the PRC’s requirement of prior permission for warships exercising innocent passage in the territorial sea; its asserted authority to prevent and punish violations of its “security” laws in the contiguous zone; and its restrictions on military activities in the EEZ.

Finally, consistent with the findings in Limits in the Seas No. 143, the PRC’s claim to “historic rights in the South China Sea” is plainly inconsistent with international law to the extent it exceeds the PRC’s possible maritime entitlements provided for in the international law of the sea, as reflected in the Convention. The PRC’s historic rights claim has been protested by the United States and many other States and was rejected by the tribunal in The South China Sea Arbitration. 

The overall effect of these maritime claims is that the PRC unlawfully claims sovereignty or some form of exclusive jurisdiction over most of the South China Sea. These claims, especially considering their expansive geographic and substantive scope, gravely undermine the rule of law in the oceans and numerous universally recognized provisions of international law reflected in the Convention."

- Excerpted Conclusion of the US Department of State position paper, Limits in the Seas No. 150, entitled "People's Republic of China: Maritime Claims in the South China Sea"