UN Convention on the Law of the Sea

The United Nations Convention on the Law of the Sea, adopted in 1982 and entering force in 1994, is the foundational treaty governing maritime rights. It codifies transit passage through international straits, exclusive economic zones, continental shelf rights, and freedom of navigation. 168 state parties have ratified it; the United States has not, though it treats most provisions as customary international law.

The 2026 Iran conflict has placed UNCLOS under the most severe structural stress since its entry into force. Iran demands sovereignty over the Strait of Hormuz as a peace condition — a claim that directly contradicts UNCLOS's guarantee of transit passage through international straits used for international navigation. The IRGC's toll system, charging vessels up to $2 million per VLCC transit in yuan or stablecoins, violates the convention's core principle that straits connecting high seas cannot be subject to unilateral fees. The EU formally rejected Trump's suggestion of a US-Iran joint toll-collection venture, noting it would breach UNCLOS customary law. The 51-nation Paris mission's legal spine rests on UNCLOS transit-passage doctrine, and IMO Secretary-General Arsenio Dominguez invoked UNCLOS in his 17 April statement covering 20,000 stranded seafarers.

The Iran-Oman bilateral transit protocol confirmed by IRNA on 27 April introduces a novel UNCLOS-compliant workaround: because Oman's territorial waters cover the southern half of the 33-kilometre strait, a toll administered through Oman sits within a UNCLOS-party state's sovereign jurisdiction rather than as a unilateral imposition on an international strait. Whether this manoeuvre is compatible with UNCLOS's transit-passage protections will depend on whether the protocol is structured as a fee for services (potentially permissible) or a toll on transit passage (prohibited).

Beyond Hormuz, UNCLOS governs the legal framework for maritime operations in the Black Sea (Russia-Ukraine), South China Sea (China-Philippines-Vietnam disputes), and Arctic (shipping route sovereignty claims). The convention's enforcement gap — no binding mechanism to compel compliance — has been exposed in each theatre.

Article 38 of UNCLOS is the operative clause in the 2026 Hormuz dispute: it guarantees the right of transit passage through straits used for international navigation between one part of the high seas and another, with no toll or prior-authorisation requirement. Iran has never ratified UNCLOS, meaning Article 38 carries no force in Iranian domestic law. The Majlis Hormuz sovereignty law of 2 May 2026 exercises Iranian domestic jurisdiction instead.

On 15 May 2026, Iranian Foreign Minister Araghchi confirmed to India's Jaishankar that Iran and Oman had entered maritime security consultations. Oman is a UNCLOS party whose territorial waters cover the southern half of the strait — a co-administrator status that gives Tehran's Oman consultation track legal significance: if Iran can channel the toll mechanism through Oman, the architecture shifts from a non-party unilateral imposition to an arrangement administered partly inside a UNCLOS-party state's sovereign jurisdiction. That would strip the Western Coalition's UNCLOS legal foundation for opposing the toll.

The legal collision between UNCLOS Article 38 transit-passage guarantees and Iran's domestic Hormuz jurisdiction statute is the foundational legal dispute of the war's maritime dimension. Azizi's 16 May Hormuz mechanism announcement — backed by four parallel institutions — makes the collision structural rather than provisional.