States that are party to UNCLOS could bring legal action against U.S. entities for not following UNCLOS in foreign courts

A second potential means to compel compliance with UNCLOS regimes would be for a foreign state, corporation, or even an NGO to bring an action against the United States, or, perhaps more likely, a U.S.-licensed corporation in a foreign domestic jurisdiction. The enforcing party would be required to bring its action in a jurisdiction with domestic law incorporating UNCLOS obligations. Enforcement of UNCLOS in a foreign domestic court would depend on the relationship between treaties and the foreign nation’s domestic law.¹⁸⁵ Nations fall into two categories in how they implement treaties into their domestic law. Some states convert treaties into domestic law automatically¹⁸⁶ and in an UNCLOS member state taking such an approach, UNCLOS would be enforceable in a foreign domestic court without any further action required by the member state. In contrast, some nations require implementing legislation before a treaty is enforceable as domestic law.¹⁸⁷ In such a nation, UNCLOS would either need to be made self-executing upon ratification, or be implemented through separate legislation.¹⁸⁸

In either case, if a state is willing to incorporate UNCLOS provisions into its domestic law, it is foreseeable that the state might also insist that corporations conducting business within the state comply with UNCLOS. For example, state A might establish a rule that before corporation Z does business within A, Z must demonstrate that its international business is conducted consistent with UNCLOS. Further, if Z is already doing business within A and undertakes a new non-UNCLOS-compliant venture elsewhere, A might subject Z to penalties. Alternatively, A might allow private causes of action to be brought by third-party corporations or NGOs against Z as a way to compel UNCLOS compliance. Chevron, Exxon, and Coca-Cola are some of the U.S. corporations that have been forced to endure long and expensive litigation in a foreign domestic court for charges ranging from environmental pollution to human rights violations.¹⁸⁹