The Strait of Hormuz stands as one of the most strategically significant maritime chokepoints in the world. Connecting the Persian Gulf with the Gulf of Oman and the Arabian Sea, it serves as the primary artery for global energy supplies. Geographically, at its narrowest point, the strait is approximately 21 nautical miles wide, meaning that the entirety of its waters falls within the territorial seas of the coastal states—Oman and Iran—under the standard 12-nautical-mile limit. This geographical reality creates a complex legal friction between the sovereign rights of coastal states and the navigational freedoms essential for international commerce.
The legal regime governing the Strait of Hormuz is not merely a matter of academic debate; it is a flashpoint for geopolitical tension. The primary instrument of modern maritime law, the United Nations Convention on the Law of the Sea (UNCLOS), provides a framework for transit passage through international straits. However, the application of this framework is complicated by the fact that Iran, a key coastal state, has signed but not ratified the Convention. Consequently, the interaction between treaty law and customary international law (CIL) becomes the focal point of legal analysis. This article explores the legal status of the Strait of Hormuz, analyzing the conflicting interpretations of transit passage versus innocent passage, the rights of coastal states, and the implications of state practice under the broader umbrella of international maritime law.
The Strait of Hormuz stands as one of the most strategically significant maritime chokepoints in the world. Connecting the Persian Gulf with the Gulf of Oman and the Arabian Sea, it serves as the primary artery for global energy supplies. Geographically, at its narrowest point, the strait is approximately 21 nautical miles wide, meaning that the entirety of its waters falls within the territorial seas of the coastal states—Oman and Iran—under the standard 12-nautical-mile limit. This geographicaThe Strait of Hormuz stands as one of the most strategically significant maritime chokepoints in the world. Connecting the Persian Gulf with the Gulf of Oman and the Arabian Sea, it serves as the primary artery for global energy supplies. Geographically, at its narrowest point, the strait is approximately 21 nautical miles wide, meaning that the entirety of its waters falls within the territorial seas of the coastal states—Oman and Iran—under the standard 12-nautical-mile limit. This geographica
II. Historical Evolution of the Regime of Straits
Historically, the legal status of straits used for international navigation was governed by the principle of ‘Innocent Passage,’ a concept solidified in the 1958 Geneva Convention on the Territorial Sea and the Contiguous Zone. Under innocent passage, foreign vessels have the right to traverse territorial waters as long as their passage is not prejudicial to the peace, good order, or security of the coastal state. Crucially, innocent passage allows coastal states to temporarily suspend passage for security reasons and requires submarines to navigate on the surface.
As the reach of territorial seas expanded from 3 miles to 12 miles during the mid-20th century, many straits that were previously high seas became entirely territorial waters. To prevent coastal states from strangling international trade, the Third UN Conference on the Law of the Sea introduced the regime of ‘Transit Passage.’ This regime is more permissive than innocent passage: it cannot be suspended, it includes the right of overflight, and it allows for ‘normal modes’ of transit, which arguably includes submerged passage for submarines. The Strait of Hormuz became the primary testing ground for these competing legal standards.
Historically, the legal status of straits used for international navigation was governed by the principle of ‘Innocent Passage,’ a concept solidified in the 1958 Geneva Convention on the Territorial Sea and the Contiguous Zone. Under innocent passage, foreign vessels have the right to traverse territorial waters as long as their passage is not prejudicial to the peace, good order, or security of the coastal state. Crucially, innocent passage allows coastal states to temporarily suspend passage fHistorically, the legal status of straits used for international navigation was governed by the principle of ‘Innocent Passage,’ a concept solidified in the 1958 Geneva Convention on the Territorial Sea and the Contiguous Zone. Under innocent passage, foreign vessels have the right to traverse territorial waters as long as their passage is not prejudicial to the peace, good order, or security of the coastal state. Crucially, innocent passage allows coastal states to temporarily suspend passage f
III. The UNCLOS Framework: Transit Passage vs. Innocent Passage
Part III of UNCLOS (Articles 34 to 45) defines the regime of transit passage. Article 38(2) defines transit passage as the exercise of the freedom of navigation and overflight solely for the purpose of continuous and expeditious transit. While the coastal states retain sovereignty over the waters, their regulatory power is strictly limited to matters of safety, pollution control, and the prevention of fishing (Article 42).
The ‘Iran Gap’ is the most significant hurdle in the Strait. Iran maintains that because it has not ratified UNCLOS, it is not bound by the ‘Transit Passage’ regime, which it views as a contractual benefit for parties to the treaty. Instead, Iran argues that the Strait is governed by the 1958 Convention and customary law, which only guarantee ‘Innocent Passage.’ Under this view, Iran claims the right to monitor, challenge, and potentially restrict passage for warships or vessels from states it deems hostile (notably the United States, which is also a non-party to UNCLOS).
Conversely, the United States and most of the international community argue that the transit passage provisions of UNCLOS have crystallized into Customary International Law. Therefore, these rights apply to all states regardless of their treaty status. This legal impasse leads to frequent ‘maneuvering’ in the Strait, where Iranian naval forces attempt to enforce a ‘prior authorization’ or ‘notification’ requirement that the US and other Western powers categorically reject as a violation of international law.
Part III of UNCLOS (Articles 34 to 45) defines the regime of transit passage. Article 38(2) defines transit passage as the exercise of the freedom of navigation and overflight solely for the purpose of continuous and expeditious transit. While the coastal states retain sovereignty over the waters, their regulatory power is strictly limited to matters of safety, pollution control, and the prevention of fishing (Article 42).
The ‘Iran Gap’ is the most significant hurdle in the Strait. Iran maintaPart III of UNCLOS (Articles 34 to 45) defines the regime of transit passage. Article 38(2) defines transit passage as the exercise of the freedom of navigation and overflight solely for the purpose of continuous and expeditious transit. While the coastal states retain sovereignty over the waters, their regulatory power is strictly limited to matters of safety, pollution control, and the prevention of fishing (Article 42).
The ‘Iran Gap’ is the most significant hurdle in the Strait. Iran mainta
IV. Sovereignty and Jurisdiction: The Coastal State Perspective
Coastal states possess the right to protect their marine environment and ensure maritime safety. Article 42 of UNCLOS allows Oman and Iran to establish sea lanes and traffic separation schemes (TSS). In fact, the TSS in the Strait of Hormuz lies largely within Omani territorial waters. While Oman has ratified UNCLOS, its domestic legislation (Royal Decree No. 1/81) originally contained language suggesting that foreign warships might need prior permission. However, Oman generally adheres to the transit passage regime in practice to maintain stability.
The legal tension escalates when coastal states invoke ‘security’ to justify interference. Iran has frequently cited ‘environmental protection’ or ‘maritime accidents’ as pretexts for seizing tankers, such as the Stena Impero in 2019. From a legal lens, such seizures are highly scrutinized. Unless a vessel is actively engaged in a threat or use of force against the coastal state (violating Article 39), the coastal state lacks the jurisdiction to impede its transit under the transit passage regime.
Coastal states possess the right to protect their marine environment and ensure maritime safety. Article 42 of UNCLOS allows Oman and Iran to establish sea lanes and traffic separation schemes (TSS). In fact, the TSS in the Strait of Hormuz lies largely within Omani territorial waters. While Oman has ratified UNCLOS, its domestic legislation (Royal Decree No. 1/81) originally contained language suggesting that foreign warships might need prior permission. However, Oman generally adheres to the tCoastal states possess the right to protect their marine environment and ensure maritime safety. Article 42 of UNCLOS allows Oman and Iran to establish sea lanes and traffic separation schemes (TSS). In fact, the TSS in the Strait of Hormuz lies largely within Omani territorial waters. While Oman has ratified UNCLOS, its domestic legislation (Royal Decree No. 1/81) originally contained language suggesting that foreign warships might need prior permission. However, Oman generally adheres to the t
V. Military Navigation and the Issue of Submerged Transit
The most contentious aspect of the Strait’s legal regime is the passage of warships and submarines. Under innocent passage, submarines must surface. Under transit passage, they may transit in their ‘normal mode,’ which for a submarine is submerged. The US Navy consistently operates on the basis of transit passage, asserting that submerged transit is essential for the safety and stealth of its fleet. Iran’s position—that only innocent passage applies—would theoretically require US nuclear submarines to surface, a demand the US ignores.
Furthermore, the right of ‘overflight’ is a hallmark of transit passage. In the absence of this right, military aircraft would need permission to enter the airspace above the Strait. By insisting on the customary status of UNCLOS Part III, the international community ensures that the Strait remains an open corridor for aerial logistics and patrols, which are vital for regional security operations.
The most contentious aspect of the Strait’s legal regime is the passage of warships and submarines. Under innocent passage, submarines must surface. Under transit passage, they may transit in their ‘normal mode,’ which for a submarine is submerged. The US Navy consistently operates on the basis of transit passage, asserting that submerged transit is essential for the safety and stealth of its fleet. Iran’s position—that only innocent passage applies—would theoretically require US nuclear submariThe most contentious aspect of the Strait’s legal regime is the passage of warships and submarines. Under innocent passage, submarines must surface. Under transit passage, they may transit in their ‘normal mode,’ which for a submarine is submerged. The US Navy consistently operates on the basis of transit passage, asserting that submerged transit is essential for the safety and stealth of its fleet. Iran’s position—that only innocent passage applies—would theoretically require US nuclear submari
VI. Conclusion and Recommendations
The Strait of Hormuz remains a legal anomaly where geopolitical interests collide with evolving maritime norms. While UNCLOS provides a sophisticated blueprint for ‘Transit Passage,’ the refusal of key actors to fully ratify or acknowledge the customary nature of these rules creates a ‘gray zone’ of jurisdiction.
To ensure long-term stability, it is imperative that international law is interpreted constructively rather than restrictively. The rights of coastal states to protect their environment and security must be balanced against the global necessity of unhindered energy flow. Constructive suggestions include the formalization of a ‘Code of Conduct’ for the Strait, independent of the UNCLOS ratification status, and the strengthening of multilateral maritime security constructs like the International Maritime Security Construct (IMSC). Ultimately, the Strait of Hormuz should not be viewed through the lens of zero-sum sovereignty, but as a global common that requires the rigorous application of international law to prevent conflict and ensure economic continuity.
The Strait of Hormuz remains a legal anomaly where geopolitical interests collide with evolving maritime norms. While UNCLOS provides a sophisticated blueprint for ‘Transit Passage,’ the refusal of key actors to fully ratify or acknowledge the customary nature of these rules creates a ‘gray zone’ of jurisdiction.
To ensure long-term stability, it is imperative that international law is interpreted constructively rather than restrictively. The rights of coastal states to protect their environmeThe Strait of Hormuz remains a legal anomaly where geopolitical interests collide with evolving maritime norms. While UNCLOS provides a sophisticated blueprint for ‘Transit Passage,’ the refusal of key actors to fully ratify or acknowledge the customary nature of these rules creates a ‘gray zone’ of jurisdiction.
To ensure long-term stability, it is imperative that international law is interpreted constructively rather than restrictively. The rights of coastal states to protect their environme
REFERENCES / FOOTNOTES
1. United Nations Convention on the Law of the Sea, Dec. 10, 1982, 1833 U.N.T.S. 397 [hereinafter UNCLOS].
2. Michael N. Schmitt, ‘The Strait of Hormuz and the Use of Force,’ Naval War College Review 66, no. 1 (2013): 13-25.
3. Convention on the Territorial Sea and the Contiguous Zone, Apr. 29, 1958, 15 U.S.T. 1606, 516 U.N.T.S. 205.
4. See Corfu Channel Case (U.K. v. Alb.), Judgment, 1949 I.C.J. Rep. 4 (Apr. 9).
5. Nilufer Oral, ‘Transit Passage Rights in the Strait of Hormuz,’ ASIL Insights 23, no. 6 (2019).
6. R.R. Churchill & A.V. Lowe, The Law of the Sea (3rd ed., Manchester Univ. Press 1999), 102-115.
7. Tommy T.B. Koh, ‘A Constitution for the Oceans,’ Remarks at the Third UN Conference on the Law of the Sea (1982).
8. Iranian Maritime Areas Law of 1993, Art. 9, translated in 2 Law of the Sea Bulletin (1993).
9. Restatement (Third) of Foreign Relations Law of the United States § 513 (1987).
10. James Kraska, Maritime Power and the Law of the Sea (Oxford Univ. Press 2011), 145.
Author: Ramansh Pareek
Juris Centre 