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
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
Furthermore, experts often disagree on the existing norms of international law.122 The ambiguity exists because the international customary law that applies to ocean activities is derived from numerous conventions, judicial decisions, state practice, and interpretations by international organizations. The customary law is not universally accepted, and it changes over time based on state practice.123 To obtain financing and insurance and avoid litigation risk, “U.S. companies want the legal certainty that would be secured through the Convention’s procedures in order to engage in oil, gas, and mineral extraction on our extended continental shelf.”124 Also, American companies may not use customary law to claim the right to seabed mining. There is no customary practice for dealing with seabed mining, and such practice is necessary for the formation of customary law.125
Moreover, because it is so difficult to prove the extent of customary law, according to some experts, “[a]bsent express agreement, mandatory obedience to the decisions of international organizations or tribunals is for all practical purposes out of the question.”126 The weaker the sense of legitimacy, the less restrained state practice is likely to be. There is a tendency among nations “to take treaty obligations more seriously than customary law obligations,” which leads to increased self-restraint.127 As Admiral Mullen testified when he was Vice Chief of Naval Operations, “[i]t is too risky to continue relying upon unwritten customary international law as the primary legal basis to support U.S. military operations.”128
There is significant danger in relying so heavily on customary international law to support U.S. desires, and especially to guarantee the movement of our naval expeditionary forces. Customary law is inherently "fuzzy around the edges" and vague on details. This customary law is constantly evolving through a process of claim and counter claim,55 representing an inherently unstable landscape. Some states, especially newly indepen- dent states, do not recognize customary law. They view it as a body of law, frequently formed without their participation or consent, that promotes the interests of developed nations—often former colonial powers—without considering and reflecting those of the developing world56. Finally, customary law is especially difficult to enforce and maintain, requiring, for example, the comprehensive U.S. Freedom of Navigation Program to maintain57 the United States' desired level of freedom of navigation and overflight.
Legal scholars have noted that governments are more inclined to respect obligations to which formal consent has been given by the highest political authorities and that even if the Convention is declaratory of customary international law, this leaves much room for argument about important details. They further argue that without widespread ratification of the Convention, inevitable "violations" are more easily interpreted as evi- dence that state practice, the ultimate source of customary law, is not necessarily rooted 58 in the Convention.