U.S. will be bound by UNCLOS provisions on interdiction regardless through customary international law without being able to guide the discussion

Nevertheless, opponents of UNCLOS find that United States accession to the treaty would directly contradict the goals of PSI.³¹ Specifically, opponents assert that if the United States does not become a party to the Convention, it will be free from any constraints in relation to ocean law, and thus, better suited to pursue the goals of PSI.³² This argument, however, is weakened by the fact that the United States is already a party to the 1958 Convention on the Law of the Sea, subjecting it to many of the same provisions articulated in the current iteration of UNCLOS.³³ While the 1982 Convention modified many elements of the 1958 Convention, several key provisions remained in place, including many governing activities in territorial seas, continguous zones, and the high seas. Additionally, because UNCLOS is largely rooted in customary law, opponents of UNCLOS assert that the United States is already subject to many of its provisions implicitly.³⁴ In the absence of a treaty, the United States must rely on and abide by customary law, which is defined by the pattern and practice of states. Since so many nations are already a party to UNCLOS, their practices largely influence the body of customary law on which the United States must rely if it does not ratify UNCLOS.