US can enjoy all navigational freedoms ensured by UNCLOS without acceding to it

Yet proponents of U.S. accession to UNCLOS maintain that the United States cannot fully benefit from these navigational rights unless it is a party to the convention, which “provides” and “preserves” these rights. This is simply incorrect. The United States enjoys the same navigational rights as UNCLOS parties enjoy.

At the December 1982 final plenary meeting of the Third United Nations Conference on the Law of the Sea, some nations took the opposite position, contending that any nation that chose not to join the convention would forgo all of these rights. On March 8, 1983, the United States, exercising its right to reply, expressly rejected that position:

Some speakers discussed the legal question of the rights and duties of States which do not become party to the Convention adopted by the Conference. Some of these speakers alleged that such States must either accept the provisions of the Convention as a “package deal” or forgo all of the rights referred to in the Convention. This supposed election is without foundation or precedent in international law. It is a basic principle of law that parties may not, by agreement among themselves, impair the rights of third parties or their obligations to third parties. Neither the Conference nor the States indicating an intention to become parties to the Convention have been granted global legislative power....

The United States will continue to exercise its rights and fulfil its duties in a manner consistent with international law, including those aspects of the Convention which either codify customary international law or refine and elaborate concepts which represent an accommodation of the interests of all States and form part of international law.

In sum, it is not essential or even necessary for the United States to accede to UNCLOS to benefit from the certainty and stability provided by its navigational provisions. Those provisions either codify customary international law that existed well before the convention was adopted in 1982 or “refine and elaborate” navigational rights that are now almost universally accepted as binding international law.