Customary international law is no longer viable because of the increasing number of excessive claims

UNCLOS opponents are correct on at least one point. The customary international law of the sea – at least as generally understood today – is consistent with U.S. national security interests. The U.S. government has said as much.¹⁵Taft, William H. "Statement of William H. Taft IV (April 8, 2004): Accession to the 1982 Law of the Sea Convention and Ratification of the 1994 Agreement Amending Part XI of the Law of the Sea Convention ." Testimony before the U.S. Senate Committee on Armed Services, April 8, 2004. [ More (10 quotes) ] However, in relying on the apparent harmony between UNCLOS and customary law as rationale for the U.S. to remain outside the treaty, opponents have failed to address a critical question: What if UNCLOS or customary law changes? Is it possible that today’s favorable legal environment could evolve adversely to U.S. interests?

The question is more than speculative. Through the years, a variety of nations have advanced legal theories inconsistent with critical U.S. ocean policy interests.¹⁶ Historically, these nations have lacked the will or ability to affect meaningful change in the international law of the sea. Today, however, this dynamic is changing.

Consider, for example, U.S. military operations in the off-shore area known as the EEZ, as codified by UNCLOS, comprising the waters beyond a nation’s territorial sea extending a maximum of 200 nautical miles from the coast.¹⁷ For years, the U.S. has consistently maintained the right under customary international law to conduct military activities in coastal state EEZs.¹⁸Taft, William H. "Statement of William H. Taft IV (April 8, 2004): Accession to the 1982 Law of the Sea Convention and Ratification of the 1994 Agreement Amending Part XI of the Law of the Sea Convention ." Testimony before the U.S. Senate Committee on Armed Services, April 8, 2004. [ More (10 quotes) ] Over the past decade, however, the People’s Republic of China has initiated confrontations with U.S. ships and aircraft operating in the Chinese-claimed EEZ and its associated airspace. The Chinese have boldly rejected long-standing U.S. positions on customary international law and also challenged conventional interpretations of critical UNCLOS provisions.