US and Iran Sail in Divergent Legal Waters Over Strait of Hormuz
The complex military dynamics and economic disruptions in the Strait of Hormuz represent only part of a deeper story. Beneath the surface lies a profound legal clash between the United States and Iran, with both nations interpreting international maritime law in starkly different ways. This disagreement over the strait's status—a narrow passage through which 20% of the world's oil flows—has far-reaching implications for global trade and security.
The Strait's Legal Ambiguity
Geographically, the Strait of Hormuz is universally recognized as a strait—a narrow sea lane connecting two larger bodies of water. However, its political and legal status remains hotly contested. Washington views it as an international waterway, while Tehran asserts it falls within its territorial waters. This fundamental divergence shapes their actions: Iran's imposition of tolls on ships is deemed illegal by the US, while US blockades are seen by Iran as grave violations of sovereignty.
The Law of the Sea Framework
The "law of the sea" encompasses a network of international laws, customs, and agreements governing ocean access and control. A cornerstone is the United Nations Convention on the Law of the Sea (UNCLOS), established in 1982 and enforced since 1994. UNCLOS aims to create stable maritime zones, including international straits, with clear rules. It has been ratified by 171 countries and the European Union, but neither Iran nor the US are parties. Iran has signed but not ratified, while the US has done neither, leaving them outside the consensus that guides most nations.
Iran's Legal Perspective
Iran bases its stance on pre-UNCLOS international law, such as the 1949 Corfu Channel case and the 1958 Territorial Seas Convention. These older standards grant foreign ships a right of "innocent passage" through international straits, allowing coastal states like Iran and Oman to enforce safety and environmental rules. However, Iran controversially claims the right to suspend passage in its half of the strait, citing it as territorial sea—a move that contradicts the 1958 convention it relies on, which prohibits suspension in international straits.
The US Interpretation
The United States argues that the Strait of Hormuz requires "transit passage" as defined by UNCLOS, despite not being a signatory. This interpretation favors free navigation, requiring coastal states to allow continuous and expeditious passage, including overflight and submarine transit. The US reinforces this position through regular Freedom of Navigation patrols, rejecting what it views as excessive claims. Legal scholars like James Kraska support this stance, labeling Iran's actions as "lawfare" and urging adherence to UNCLOS compromises.
A Global Outlier and Persistent Objector
The US stands as a global outlier, joined by only a few countries like the UK and France, in asserting that transit passage is customary law. Customary law applies universally unless a nation is a "persistent objector," consistently opposing emerging standards. Iran claims this status, arguing that transit passage is tied to UNCLOS and only applies to ratifying countries. Legal experts are divided on whether transit passage has become customary, with many law of the sea specialists disputing it.
Navigating Troubled Waters
The legal complexities extend beyond US-Iran disagreements. Nations flagging oil tankers must also navigate their own commitments under maritime law. For international law to function effectively—reducing conflict and enabling trade—a shared understanding of rules and a commitment to abide by them are essential. Achieving a stable post-war status for the Strait of Hormuz requires navigating these tricky legal waters, with every nation wary of setting precedents contrary to their long-term interests.
About the author: Elizabeth Mendenhall is an Associate Professor of Marine Affairs at the University of Rhode Island. This article is adapted from The Conversation under a Creative Commons license.
