THE HAGUE, July 12 — The legal architecture governing the world’s maritime chokepoints rests on a treaty the United States never ratified and Iran signed but never fully joined. That paradox now sits at the center of a confrontation over the Strait of Hormuz, where Tehran has threatened to restrict passage for commercial and military vessels. The United Nations Convention on the Law of the Sea, signed in 1982 and effective from 1994, guarantees the right of transit passage through international straits used for international navigation.
Article 38 of UNCLOS states plainly that ships and aircraft enjoy the right of unimpeded transit passage. Iran signed the convention in 1982 but has not ratified it, meaning the Islamic Republic is not legally bound by the treaty’s terms.
The United States has not ratified UNCLOS either. But Washington recognizes its navigational provisions as customary international law, a position successive administrations have maintained. Customary international law, as reflected in UNCLOS, is widely accepted by states regardless of formal ratification.
The legal basis for challenge
If Iran were to close the strait, the record shows multiple avenues for legal challenge. The matter could be brought before the International Court of Justice in The Hague or the International Tribunal for the Law of the Sea, also based in Germany. Both bodies have jurisdiction over disputes concerning the law of the sea where the parties accept their authority.
Beyond UNCLOS, the closure would violate the 1958 Geneva Convention on the Territorial Sea and Contiguous Zone, a treaty Iran has ratified. That convention, predating UNCLOS, similarly affirms the right of innocent passage through territorial seas used for international navigation.
The timeline shows that in 2019, the United States invoked the right of freedom of navigation by deploying naval assets through the strait. That operation served as both a demonstration of military capability and a legal assertion of the transit rights Washington considers customary.
The Security Council calculus
The United Nations Security Council could pass a resolution demanding the reopening of the strait. But the diplomatic math is unforgiving. Iran’s ally Russia holds veto power on the council, meaning any resolution targeting Tehran’s actions in the waterway could be blocked before reaching a vote.
Sources familiar with Security Council dynamics note that Moscow has used its veto repeatedly to shield Iran from punitive measures. The pattern suggests that even a clear violation of international maritime law may not produce a binding council response.
The Strait of Hormuz sits at the intersection of law, power and geography. The legal instruments exist to challenge a closure. Whether they can be enforced against a state that never fully accepted them is the question that now confronts diplomats and naval commanders alike.
