WASHINGTON, July 13 — A proposal to impose tolls on vessels transiting the Strait of Hormuz would run headlong into decades of settled international maritime law, legal experts say. The practical upshot: any such fee would almost certainly violate multiple treaties the United States itself helped shape, creating a legal and diplomatic tangle for the administration. The Strait of Hormuz is an international strait governed by the United Nations Convention on the Law of the Sea, known as UNCLOS.
Signed on December 10, 1982, and effective November 16, 1994, the convention’s Article 37 guarantees what is called “transit passage” for all ships. In plain terms, that means vessels — whether oil tankers, cargo ships, or naval warships — cannot be stopped, delayed, or charged a fee simply for passing through.
The legal principle is akin to a public highway: you can’t put up a tollbooth on an interstate and demand payment from every driver just for using it. The United States has not ratified UNCLOS, a fact that sometimes confuses the public. But here’s what it means in practice: the U.S. government recognizes the convention’s core provisions as customary international law — meaning the rules bind nations whether or not they formally signed on.
Washington has a long history of acting on that view. In 1982, the same year UNCLOS opened for signature, the U.S. conducted Operation Pre-Blockade specifically to assert freedom of navigation through the strait.
The message was clear then and remains so now. Iran claims sovereignty over the strait under its 12-mile territorial sea, a position most nations reject. The proposed toll would also likely violate the 1958 Geneva Convention on the Territorial Sea and Contiguous Zone, specifically Article 16, which prohibits the suspension of innocent passage through straits used for international navigation.
That treaty predates UNCLOS and the U.S. did ratify it. Any toll would face a second hurdle entirely separate from international law: the U.S. Constitution. Article I, Section 8 vests Congress with the power to impose duties and tariffs.
A toll on foreign vessels crossing an international strait would require explicit Congressional authorization. The 1974 Trade Act provides another potential avenue for legal challenge, as it governs the president’s authority to adjust imports and tariffs.
Where the challenge would land
If the toll moved forward, the United States could face proceedings at two international bodies. The International Court of Justice in The Hague handles disputes between states under treaties like the Geneva Convention. The International Tribunal for the Law of the Sea, established in 1996 and also based in Germany, has specific jurisdiction over UNCLOS matters.
Either forum could hear a case brought by affected nations — likely including major oil importers and shipping states. There is recent precedent for economic pressure on Iran that did not run afoul of maritime law.
In 2012, the European Union imposed an oil embargo on Iran on January 23 of that year. That action was legal under EU law because it targeted purchases of Iranian crude, not the transit of vessels through international waters. The distinction matters: embargoes restrict what you buy; a toll restricts where you sail.
What to watch next
The administration has not formally proposed legislation to authorize such a toll, and the legal obstacles are substantial. Congressional leaders on both the relevant committees would need to weigh whether the constitutional and treaty-based barriers can be overcome. Meanwhile, any actual attempt to collect a fee in the strait itself would almost certainly trigger immediate challenges from shipping nations and possibly from the U.S. Navy’s own Fifth Fleet, which operates in the region under the same freedom-of-navigation principles the United States has defended for decades.
