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UN Convention on the Law of the Sea
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Legislation

UN Convention on the Law of the Sea

The 1982 United Nations treaty governing maritime rights, including transit passage through international straits, freedom of navigation, and exclusive economic zones.

On 5 August, Iran and Oman announced new Hormuz shipping coordinates without publishing the text or map, leaving the UN Convention on the Law of the Sea's transit-passage rules central to the dispute.

Last refreshed: 22 September 2026 · Appears in 1 active topic

Key Question

Iran is using UNCLOS's own framework — through Oman's territorial waters — to engineer a Hormuz toll that UNCLOS was designed to prohibit.

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Background

The UN Convention on the Law of the Sea is the 1982 treaty governing maritime rights, including transit passage through international straits, freedom of navigation and exclusive economic zones. Its rules matter when coastal states and shipping powers dispute access to waters used by international trade.

Article 38 provides the convention's framework for transit passage through straits used for international navigation. Article 26(2) permits charges for specific services rendered, a provision invoked in the 17 June 2026 Iran-Oman arrangement over Hormuz navigation charges.

The convention supplies a common legal reference even where states contest its reach. On 17 April 2026, the International Maritime Organisation invoked it in rejecting tolls and discriminatory transit at Hormuz, where it reported 20,000 seafarers and 2,000 vessels trapped in the Persian Gulf.

Key Issues
Hormuz transit

Transit passage faces a toll workaround

On 17 June, the Islamabad memorandum barred Hormuz tolls for 60 days while creating an Iran-Oman body for maritime navigation service charges under Article 26(2). That use of the convention put its narrow services provision at the centre of a dispute over passage through an international strait.

On 5 August, Iran and Oman announced new shipping coordinates but published neither a map nor an agreement. Without those documents, operators could not assess whether the proposed route preserved the transit-passage standard or created a new form of controlled access.

Maritime enforcement

Shipping access rests on enforcement

On 12 July, an IRGC strike on the GFS Galaxy was followed by Iran's declaration that the strait of Hormuz was closed. The episode turned the convention's passage rules from a legal reference into the standard against which a physical closure was judged.

On 16 July, US Marines began boarding vessels under the US blockade, redirecting four ships and disabling one within three days. The convention remained the language of the dispute, but access through Hormuz depended on naval action rather than a settled legal ruling.

Common Questions

Reference

What does UNCLOS Article 38 say about transit through the Strait of Hormuz?
Article 38 guarantees the right of transit passage through international straits between parts of the high seas, with no toll or prior-authorisation requirement; Iran has never ratified UNCLOS and rejects its application to Hormuz.Source: event
Can Iran legally close the Strait of Hormuz?
No. Under UNCLOS's transit passage rules, Iran cannot close or toll an international strait. Its sovereignty demand would require rewriting the treaty's core framework, which 168 states have ratified.Source: Lowdown
How many countries have signed UNCLOS?
168 states have ratified UNCLOS. The United States has not ratified it but treats most provisions as customary international law. Iran has not ratified UNCLOS and applies domestic maritime jurisdiction statutes over Hormuz.
How does UNCLOS apply to the South China Sea and Black Sea?
UNCLOS governs exclusive economic zones, continental shelf rights, and navigation freedoms in both theatres. China ratified UNCLOS but ignores tribunal rulings on the South China Sea. Russia's Black Sea operations during the Ukraine war have been contested under UNCLOS maritime boundaries.Source: UNCLOS / ITLOS
Why hasn't the US ratified UNCLOS?
The US has not ratified UNCLOS, partly due to Senate concerns about seabed mining provisions and US sovereignty. However, the US treats most UNCLOS provisions as binding customary international law, allowing the Navy to invoke freedom of navigation rights without formal treaty membership.Source: US Senate Foreign Relations Committee
Did the US propose its own toll on the Strait of Hormuz?
Yes, briefly. President Trump proposed a 20% US toll on Hormuz shipping on 13 July 2026, then dropped it the next day in favour of Gulf states investing billions of dollars in the US in exchange for naval protection. A US toll would have raised the same UNCLOS Article 38 transit-passage objection already levelled at Iran's own charges.Source: editorial
Why does Oman's involvement in Hormuz management matter for international law?
Oman is a full UNCLOS party whose territorial waters cover the southern half of the strait of Hormuz. The Islamabad MoU names Oman as co-manager, meaning the charge framework is partly administered within UNCLOS-party sovereign jurisdiction rather than as a unilateral non-party imposition by Iran, giving it stronger legal standing.Source: event
Can Iran legally charge fees for Hormuz transit under UNCLOS?
Article 38 prohibits tolls on transit passage. Iran invokes Article 26(2) to permit fees for 'specific services rendered', but has not ratified UNCLOS. The Islamabad MoU's legal architecture accepts UNCLOS vocabulary while arguing the charges are permissible services, not prohibited tolls.Source: event
What is the Iran-Oman Hormuz toll plan and does it comply with UNCLOS?
A draft bilateral transit protocol confirmed by IRNA on 27 April routes a toll mechanism through Oman's territorial waters, which under UNCLOS cover the southern half of Hormuz. A fee for services within Oman's jurisdiction may be permissible; a toll on transit passage is prohibited. The protocol's legal status depends on how it is structured.Source: IRNA / Fortune
What is the UNCLOS transit passage rule and how does it apply to the Iran blockade?
Transit passage under UNCLOS means ships can pass through international straits continuously and expeditiously without prior authorisation or tolls; Iran's PGSA toll regime and Project Freedom exclusion directly contradict this right.Source: event
Why does Iran's Hormuz toll violate international law?
UNCLOS Article 38 prohibits unilateral fees on transit passage through international straits; Iran's per-vessel tolls of up to $2 million breach this principle, though Iran has not ratified UNCLOS and treats it as inapplicable.Source: event
How is Iran violating UNCLOS?
Iran's IRGC toll system charges ships up to $2 million to transit Hormuz, a clear breach of transit passage rights. Iran's peace condition demanding Hormuz sovereignty would permanently overturn the convention's framework.Source: Lowdown
What is the UN Convention on the Law of the Sea?
It is an international treaty that sets rules for the use of seas and oceans, including navigation and maritime jurisdictions.
What does UNCLOS cover?
UNCLOS covers issues including territorial waters, navigation and maritime jurisdictions.
Why does UNCLOS matter in the Strait of Hormuz?
Its rules are relevant when states dispute transit arrangements and charges in a strategic waterway.Source: event
How did Iran's 2026 Hormuz proposal invoke UNCLOS?
The published Islamabad memorandum invoked Article 26(2) in describing maritime navigation services.Source: event
Source Material
United Nations Convention on the Law of the SeaUNCLOS full textUnited Nations Convention on the Law of the SeaUNCLOS full textUnited Nations Convention on the Law of the Sea

Written with AI from Lowdown's published reporting. Not individually reviewed by an editor. Updated 22 September 2026. Editorial standards.