Customary international law is inferior to UNCLOS a for protecting U.S. Naval rights for a number of reasons

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.