Customary international law is no longer sufficient to protect U.S. interests
Opponents of UNCLOS claim that the United States should not become a party because the United States already enjoys the benefits of UNCLOS through customary law and, therefore, should not unnecessarily incur the treaty's burdens. However, this ignores the fact that customary law can change and can also be influenced by how parties to UNCLOS decide to interpret its provisions.
Quicktabs: Arguments
Custom can also develop rapidly based upon interpretations of treaties, as well as the rulings and declarations of international bodies and courts that can declare an existing customary rule.87 In the past 50 years, customary rules have developed quickly in response to technological innovation or in times of fundamental change.88 Moreover, rapid changes to custom do not require multiple instances of state practice,89 particularly when a state with special influence in the field seeks change.90 Most recently, the terrorist attacks on the World Trade Center and Pentagon resulted in changed custom concerning the use of force in self-defense against non-state actors91 and those who support or harbor terrorists.92 Such changes to the well-settled field of international humanitarian law would have been unthinkable in an earlier era.
Some columnists and think tank analysts have argued that U.S. accession to the Convention is unnecessary because excessive maritime claims can be addressed by invoking customary international law and with “operational assertions’’ by the U.S. military. But such an approach is less certain, more risky, and more costly than taking advantage of the Convention. Customary law is by nature subject to varying interpretations and change over time. Operational assertions—sending military ship and aircraft into contested areas—involve risk to naval personnel as well as political costs. Such assertions should be conducted aggressively where needed, but avoided where possible.
International customary laws have developed out of “concordant practice by a number of states . . . over a considerable period of time,” when such practice is thought to be required by, or consistent with, the prevailing international law, and when such practice is generally accepted by other states.117 As mentioned in section III, the Convention itself is based in part on international customary laws. In addition, when an issue is not regulated by the Convention, the customary laws serve a gap-filling role, and because the Convention binds only its signatories, customary international law remains an important means of transacting with non-signatories of the Convention.118 However, the Convention expands the “existing norms to suit new developments where the existing norms are no longer sufficient,” creates new norms, and in some cases replaces old norms that are no longer appropriate.119 Thus, asserting customary international law will not secure all the benefits of the Convention for the United States because the signatories of the Convention do not have to extend specific rights established in the Convention, or those which are modifications of the existing rules, to non-signatories.120 For example, Canada may choose not to grant the United States the right of scientific research in the EEZ or in the continental shelf.121
If it ratifies UNCLOS, the United States seeks to gain “maximum freedom to navigate and operate off foreign coasts without interference,” for both security and economic purposes.87 If the United States does not ratify UNCLOS, it may attempt to assert these freedoms under customary international law. However, its ability to do so is growing weaker, as when coastal States extend their exclusive economic zones, “customary international law may . . . evolve[] in a way contrary to [American] [i]nterests.”88 Customary law is “not universally accepted, evolves based on State practice, and does not provide access to the Convention’s procedural mechanisms, such as the continental shelf commission.”89 The United States may make excessive maritime claims through customary international law or military operations, but either such approach is “less certain, more risky, and more costly” than working under the UNCLOS framework.90