UNCLOS provisions on freedom of navigation have already archived status of customary international law

Most of the UNCLOS navigational provisions have long been recognized as customary international law. The convention’s articles on navigation on the high seas (Articles 86–115, generally) and passage through territorial waters (Articles 2–32, generally) were copied almost verbatim from the Convention on the High Seas and the Convention on the Territorial Sea and the Contiguous Zone, both of which were adopted in 1958. The United States is party to both conventions, which are considered to be codifications of widely accepted customary international law.

Similar to other multilateral conventions, such as the Vienna Convention on Diplomatic Relations, UNCLOS is said to “have codified settled customary international law or to have ‘crystallized’ emerging customary international law.” UNCLOS codified customary law relating to navigation on the high seas and through territorial waters and “crystallized” emerging customary law, such as the concepts of “transit passage” through international straits and “archipelagic sea-lanes passage.” As summarized by Defense Department official John McNeill in 1994, UNCLOS “contains a comprehensive codification of long-recognized tenets of customary international law which reflect a fair balance of traditional ocean uses.” In short, the convention’s navigational provisions have attained such a status that all nations—UNCLOS members and nonmembers alike—are expected to adhere to them.