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At its narrowest point, the Strait of Hormuz measures 21 nautical miles – a dimension that, in physical terms, is unremarkable. In legal and geopolitical terms, it is arguably the most consequential maritime measurement on Earth.
Through this corridor between the Iranian coastline to the north and the Omani peninsula of Musandam to the south, more than 21 million barrels of crude oil and approximately 20 per cent of global liquefied natural gas trade transit daily. No other chokepoint – not Suez, not Malacca, not the Bosphorus – carries comparable systemic weight. When the Strait closes, it does not merely disrupt markets. It detonates the foundational assumptions upon which the post-war international economic order was constructed.
Those assumptions have been detonating since late February. Following joint US-Israeli military strikes on Iranian nuclear facilities, shipping traffic through the Strait ground to a near halt. Brent crude peaked at $126 per barrel – its highest level in four years. The International Energy Agency characterised the disruption as the gravest shock to global energy supply since the 1973 crisis. What the crisis has exposed, with clinical precision, is not merely a geopolitical emergency. It is a convergence of legal lacunae, institutional failures and strategic miscalculations that decades of scholarship and diplomacy failed to adequately address.
To understand why the Strait functions as a weapon, one must first understand why it functions at all. The Gulf littoral states – Saudi Arabia, Iran, Iraq, Kuwait, the UAE and Qatar – collectively hold the largest proven reserves of conventional hydrocarbons on Earth. The Strait is, without geographic alternative, the sole maritime exit for the entirety of that energy wealth. Every oil tanker, every LNG carrier, every petrochemical freight vessel must transit this single 21-mile aperture before reaching open sea. There is no market mechanism, no financial instrument and no diplomatic formula that substitutes for this physical reality.
The distributional architecture of Hormuz dependence is equally telling. Approximately 84 per cent of Hormuz-transiting crude flows to Asian markets: China, Japan, South Korea, India and South-East Asia. For these states – several of which rank among the world's major economic and military powers – Hormuz is not merely an energy convenience. It is a structural prerequisite for industrial civilisation. China, the world's largest crude importer, sources a substantial proportion of its supply through the Strait. Japan and South Korea possess negligible domestic hydrocarbon reserves. Their energy security is, in the most literal sense, a function of this waterway remaining navigable.
The legal regime governing the Strait of Hormuz is not, as is sometimes assumed, a settled and coherent body of rules. It is, upon rigorous examination, a contested patchwork of treaty law, asserted custom, domestic legislation and unresolved doctrinal conflict – a framework whose structural ambiguities Iran has, across four decades, exploited with considerable legal sophistication.
The primary instrument is the UN Convention on the Law of the Sea, UNCLOS, which entered into force in 1994. Under Part III, Articles 37 to 44, straits used for international navigation between one area of the high seas or exclusive economic zone and another are subject to the right of transit passage. This regime is categorically distinct from, and superior to, the older principle of innocent passage. Transit passage is non-suspendable under any circumstances; it applies equally to surface vessels, submarines transiting in submerged mode and overflight by aircraft. It cannot be made subject to prior notification, authorisation, or levy of any kind. Coastal states retain narrow regulatory competence over safety, traffic separation and environmental protection – but not over the passage right itself.
Iran has never ratified UNCLOS. Its domestic 1993 Marine Areas Act posits an entirely different legal architecture, asserting sovereign Iranian authority over passage conditions and requiring advance approval for foreign military vessels. This domestic instrument cannot, as a matter of international law, abrogate obligations arising from customary international law or binding treaty frameworks to which third states are parties. But it provides the Iranian legal position with textual grounding that cannot simply be dismissed.
The deeper paradox is this: the US has also never ratified UNCLOS – yet Washington maintains with unequivocal consistency that the transit passage regime has crystallised into binding customary international law applicable to all states, including non-parties. The legal consequence is extraordinary. The two states whose antagonism defines the Hormuz crisis are both non-parties to the governing instrument, yet each invokes it – in mutually contradictory ways – as the authoritative statement of their respective rights. This is not a legal curiosity. It is a structural fault line in the international legal order.
The foundational jurisprudential anchor for freedom of passage in international straits remains the Corfu Channel Case (ICJ, 1949), in which the court affirmed that states may not obstruct innocent passage through international straits even in a state of heightened tension. The ruling established the customary norm. However, the Corfu Channel judgment predates UNCLOS by three and a half decades, was decided outside an active armed conflict context, and did not address the specific legal interaction between transit passage rights and the law of armed conflict at sea. Its transposition to the 2026 crisis – involving active hostilities, naval interdiction and potential mining – requires doctrinal work that the existing literature has, to date, not adequately performed.
The 2026 crisis introduces a genuinely novel legal category that the existing scholarly literature has not yet named or theorised: selective passage – the deliberate, state-sanctioned restriction of maritime passage applied differentially by flag state nationality or political alignment. This conduct does not satisfy the classical definition of a naval blockade, which under the San Remo Manual and customary international humanitarian law requires impartial and effective interdiction of all shipping, notified to all belligerents and neutral states, and proportionate to the military objective. A selective restriction calibrated by the commercial or political affiliation of vessel operators is something categorically different: it is the instrumentalisation of maritime violence as a tool of discriminatory economic statecraft. No existing UNCLOS provision, no Hague Convention and no customary law norm directly addresses this conduct as a defined legal category. If the 2026 precedent stands without challenge and doctrinal response, selective passage will have been added, by default, to the arsenal of coercive statecraft available to any state controlling a maritime chokepoint.
The economic consequences of a Hormuz closure are not linear. They are multiplicative, cascading across interconnected commodity, insurance, and financial markets in ways that conventional crisis modelling consistently underestimates. Energy price surges are merely the primary transmission mechanism. Secondary effects propagate immediately into fertiliser production, petrochemical feedstock pricing, aluminium smelting and shipping insurance markets. War-risk insurance premiums in affected zones increase by orders of magnitude, rendering commercially uninsurable many routes that were, days earlier, commercially routine. Central banks confronting inflationary supply shocks of this character lack adequate monetary instruments; interest rate policy was not designed to address the deliberate closure of a single maritime chokepoint by a sovereign state.
The distributional asymmetry of this suffering is analytically significant and morally important. OECD economies with diversified supply chains, substantial strategic reserves and deep capital markets can absorb weeks of Hormuz disruption at considerable but ultimately manageable cost. The same cannot be said for Pakistan and Bangladesh, which are almost totally dependent on LNG imports from Qatar and the UAE, possess minimal storage infrastructure and operate with fiscal margins too thin to sustain sustained price shocks. For these economies, disruption translates within days into power-sector failures with direct humanitarian consequences. The IEA's largest-ever co-ordinated strategic reserve release of 400 million barrels in March could compensate for between 20 and 45 days of full closure – a figure that reveals, with uncomfortable clarity, the structural inadequacy of existing emergency architecture against a deliberate, indefinite state-imposed closure.
The most consequential institutional failure revealed by this crisis is the absence of any dedicated multilateral governance framework for critical international straits. This lacuna was not accidental. It was the product of a strategic assumption – shared by OECD states, major Asian consumers and the architects of the post-war energy order alike – that the Strait of Hormuz would, in practice, remain open. That assumption was never translated into institutional safeguards, treaty obligations or enforcement mechanisms capable of operating under conditions of active disruption.
The Montreux Convention of 1936, which has governed the Turkish Straits through nearly a century of geopolitical turbulence, provides the most instructive precedent for reform. Its durability rests not on the suppression of Turkish sovereign interests, but on their structured accommodation. Turkey retains meaningful regulatory authority while accepting enforceable international obligations on passage rights. The convention's longevity demonstrates that riparian state interests and international passage rights are not irreconcilable – they require only the political will and diplomatic architecture to balance them.
No equivalent instrument exists for Hormuz. The states with the greatest economic stake in maintaining open passage – China, Japan, India and South Korea – have historically defaulted to passive affected-party status rather than assuming the role of active institutional architects. Their combined energy dependence confers leverage that has never been converted into diplomatic capital or formal legal standing. This passivity must end.
What the international community requires is a Maritime Hormuz Stakeholder Framework: a multilateral treaty instrument encompassing Iran and Oman as riparian states, the principal user states as parties with formal rights and obligations, and a standing commission empowered to monitor compliance, receive incident reports and refer violations to appropriate international adjudicative bodies.
Such a framework would not dissolve the underlying geopolitical antagonisms between Tehran and Washington. No legal instrument could. But it would impose a structured cost on unilateral closure — a cost that presently does not exist.
The Strait of Hormuz presents international law, international relations and international trade with their most consequential simultaneous test since the end of the Cold War. It is not a crisis of geography. It is a crisis of legal architecture, institutional design and political will. The deliberate weaponisation of a critical international waterway – with selective passage rights granted by national alignment, great powers acquiescing in exchange for preferential treatment and the UN Security Council paralysed – represents a qualitative rupture in the norms that have underwritten international economic order since 1945.
The legal community's response must be commensurate with the gravity of the challenge. The crystallisation of transit passage as universal customary international law binding non-parties must be rigorously established and vigorously asserted. The doctrine of selective passage must be named, categorised and confronted as the per se violation of international law that it is. The governance gap must be filled by a multilateral instrument with genuine teeth. And the emergency architecture of the IEA must be reformed to reflect the reality that a deliberate, indefinite, state-imposed closure is not a theoretical contingency – it is an event that has now occurred.
The Strait is 21 miles wide. The legal and institutional gap it has exposed is, by any honest measure, considerably wider. Closing it demands the same precision, rigour and political seriousness that international lawyers bring to their finest work. The moment for that work is now.
