Implication of Iran Blocking the Strait of Hormuz
Published at 25 Jun 2025
Putting the Cat Among the Pigeons: A Shaky Strait and the Potential Fallout from a Hormuz Blockade
Following a series of escalating tensions between the US and Iran, the world watches with bated breath as Tehran threatens to block international shipping through the Strait of Hormuz. A major global waterway, over 20% of the world's oil passes through this narrow strait, and any disruption could send shockwaves through international trade, markets, and geopolitics. Let's take a closer look at the messy legal and political implications of a potential Hormuz blockade.
Navigating the Turbulent Waters of Maritime Law
At the heart of the issue lies the United Nations Convention on the Law of the Sea (UNCLOS), a treaty to which Iran is a party, despite the US' non-ratification. Article 38 of UNCLOS stipulates that states bordering international straits, like Hormuz, must allow the continuous and expeditious transit of vessels. Should Iran impede this right, they would breach their obligations under UNCLOS and customary maritime law. This transit passage differs from innocent passage (Article 17 UNCLOS), which coastal states can suspend in their territorial seas.
Historically, Iran has mostly skirted the edges of this boundary by harassing or detaining commercial tankers and naval vessels, such as the British-flagged Stena Impero in July 2019. Labelled as a violation of international law, the West condemned such actions, invoking the right to freedom of navigation under both international law and customary maritime norms.
Fanning the Flames: Blockades and Belligerent Acts
If Iran were to go one step further and impose a blockade, the legal implications would become more complicated. Under international law, a lawful blockade must be declared, effective, and respect the rights of neutral shipping, occurring only in the context of an armed conflict. Absent a formal war declaration, any Iranian blockade would likely be illegal, potentially violating Article 2(4) of the UN Charter, which prohibits the threat or use of force against another state's territorial integrity or political independence.
The international community has historically taken a robust stance on these matters. During the "Tanker War" phase of the Iran-Iraq War, the US reflagged Kuwaiti tankers and escorted them through the Gulf under Operation Earnest Will. When the USS Samuel B Roberts was damaged by an Iranian mine, the US retaliated with Operation Praying Mantis, justifying its actions as lawful self-defense under international law.
Fanning the Flames: NATO and Mutual Defense
In the event of a Hormuz closure, affected states would likely consider various options, both diplomatic and military. Given the permanent Security Council members' veto power, it is unlikely that the UN Security Council would grant authorization for any action under Chapter VII of the UN Charter. However, the principle of self-defense enables any state to respond without seeking diplomatic approval, as seen in the International Court of Justice's Nicaragua v United States of America [1986] ruling, which affirmed the right of self-defense to protect shipping from unlawful interference.
A military response to a Hormuz blockade would be assessed based on the criteria of necessity and proportionality, as enshrined in international treaty and customary law. Furthermore, under Article 5 of the North Atlantic Treaty (NATO), an attack on a member state's shipping could, under certain conditions, be considered an armed attack. Whether this extends to non-lethal blockades or commercial interference is less clear but remains a topic of interest among lawyers and policymakers.
Rocking the Boat: Legal and Commercial Ramifications
Should Hormuz be closed, maritime contracts would be affected, as many contain force majeure or war risk clauses. These clauses normally allow shipowners to terminate or suspend performance when extraordinary events beyond their control make navigation impossible. However, the complexity of these provisions is such that disputes may quickly arise over whether the Strait's closure constitutes an extraordinary event and whether the affected party took appropriate measures to mitigate the impact and fulfill their contractual obligations.
Alex Guest, an associate at Signature Litigation in London, warns that parties may seek to renegotiate contractual terms or bring claims for breach of contract, potentially leading to arbitration or litigation over undelivered goods or delayed shipments.
Fallout and Aftermath
As tensions simmer in the Gulf and regional powers reinforce their naval deployments, the potential for a legal crisis emerging alongside a military one grows increasingly likely. Lawyers advising shipowners, insurers, and states would be wise to prepare for a scenario in which the Strait of Hormuz becomes a hotbed for disputes centered around international treaties, maritime law, and insurance contracts. The intricate legal framework aims to balance the sovereignty claims of coastal states with the necessity of preserving uninterrupted global commerce through vital maritime chokepoints. If the worst comes to pass, the world could find itself grappling with the consequences long after the dust settles.
- The threat of Iran blocking international shipping through the Strait of Hormuz could have far-reaching consequences, impacting not only general news but also the politics surrounding war-and-conflicts.
- In the event of a Hormuz blockade, shipowners, insurers, and states may need to navigate complex legal issues related to maritime law, treaties, and insurance contracts, adding another layer of tensions to ongoing geopolitical conflicts.
