Relying on customary international law to protect naval rights is insufficient for four reasons

Opponents also contend that accession is basically unnecessary for the United States to enjoy the benefits of the Convention. On this view, we get the benefit of the rest of the world treating the Convention’s provisions as customary international law without having to sign up ourselves. And, the argument goes, if there are any deficiencies in our legal rights, the U.S. Navy can make it up through force or the threat of force. So why join the Convention and subject ourselves to, for example, third-party dispute settlement?

This argument misses some key points:

First, asserting customary international law does not secure all the benefits of the Convention for us. For example, as a non-party, we do not have access to the Continental Shelf Commission and cannot nominate nationals to sit on it.

Second, relying on customary law does not guarantee that even the benefits we do currently enjoy are secure over the long term. Customary law is not the most solid basis upon which to protect and assert U.S. national security and economic rights. It is not universally accepted and changes over time based on State practice. We therefore cannot assume that customary law will always continue to mirror the Convention, and we need to lock in the Convention’s rights as a matter of treaty law. As Admiral Mullen testified when he was Vice Chief of Naval Operations, “[it is too risky to continue relying upon unwritten customary international law as the primary legal basis to support U.S. military operations.” One irony of this debate is that some of the opponents of the Convention are the same people who most question the viability of customary international law.

Third, 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. So, while it may be true that the Navy will continue to exercise navigational rights with or without the Convention, U.S. companies are reluctant to begin costly exploration and extraction activities without the benefit of the Convention.

Fourth, military force is too blunt an instrument to protect our asserted customary international law rights, especially our economic rights. It is simply unrealistic and potentially dangerous to rely solely on the Navy to ultimately secure the benefits of the Convention. The Navy itself has made clear that treaty- based rights are one of the tools it needs in its arsenal.