“It’s only appropriate that people who are the beneficiaries of the Strait will help to make sure that nothing bad happens there.” ~ President Donald Trump
The Overview
The contemporary tensions in the Strait of Hormuz bring into sharp relief a profound and enduring dialectic within international law: the uneasy coexistence between codified legal order and the exigencies of power, particularly when States perceive their survival or strategic primacy to be at stake. The legal regime governing this narrow yet globally indispensable maritime artery is rooted in the United Nations Convention on the Law of the Sea, whose carefully negotiated provisions represent decades of diplomatic compromise, intellectual rigor, and a collective aspiration toward stability in the use of the oceans. Yet, the unfolding conduct of Iran—in selectively restricting passage to vessels deemed hostile while permitting those of friendly States—forces a re-examination of both the normative strength and the practical elasticity of this legal framework.
The starting point of any such analysis must necessarily be the juridical character of the Strait itself. The Strait of Hormuz is unequivocally a strait used for international navigation within the meaning of Part III of UNCLOS. Article 37 of the Convention provides that the regime of transit passage applies to straits used for international navigation between one part of the high seas or an exclusive economic zone and another. The Strait of Hormuz, connecting the Persian Gulf to the Gulf of Oman and the Arabian Sea, satisfies this criterion in both geographic and functional terms. It is not merely a conduit for regional traffic but a vital artery of global commerce, particularly in hydrocarbons, rendering its uninterrupted accessibility a matter of international concern.
Article 38 of the United Nations Convention on the Law of the Sea encapsulates a carefully calibrated juridical balance between the sovereignty of littoral States and the imperatives of global navigation. It affirms, in unambiguous terms, that in straits used for international navigation, all ships and aircraft are vested with a right of transit passage which admits of no obstruction. This right, however, is not without qualification: where a strait is constituted by an island of a coastal State and its mainland, the entitlement to transit passage is displaced if an alternative route of comparable navigational and hydrographic convenience exists seaward, whether through the high seas or an exclusive economic zone.
Transit passage, in its essential character, denotes the exercise of the freedoms of navigation and overflight strictly for continuous and expeditious movement between one area of the high seas or exclusive economic zone and another. Yet, the Convention adopts a pragmatic posture in recognizing that such continuity does not exclude incidental deviations necessary for entry into, departure from, or return to a bordering State, provided such acts conform to the legal conditions imposed by that State.
Activities falling outside the narrow ambit of transit passage are not immunized by this provision and remain subject to the broader normative framework of the Convention, thereby preserving the integrity and coherence of the legal regime governing the uses of the seas.
The sovereignty of coastal States over their territorial seas is articulated with clarity in Article 2(1) of UNCLOS, which affirms that “the sovereignty of a coastal State extends, beyond its land territory and internal waters… to an adjacent belt of sea, described as the territorial sea.” This sovereignty is not illusory in the context of the Strait of Hormuz; both Iran and Oman exercise territorial jurisdiction over portions of the Strait. Article 3 further permits these States to establish the breadth of their territorial sea up to a limit not exceeding 12 nautical miles. Given the narrowness of the Strait, the territorial seas of Iran and Oman overlap, effectively enveloping the entire waterway within zones of coastal State sovereignty.
However, it is precisely at this juncture that UNCLOS introduces a critical qualification—one that is both conceptually elegant and practically indispensable. The sovereignty of coastal States in straits used for international navigation is circumscribed by the regime of transit passage. Article 38(1) provides that “in straits referred to in article 37, all ships and aircraft enjoy the right of transit passage, which shall not be impeded.” This provision is not merely permissive; it is prescriptive, establishing a legal entitlement that is both universal and non-derogable in peacetime. Article 38(2) further defines transit passage as the exercise of the freedom of navigation and overflight solely for the purpose of continuous and expeditious transit of the strait.
The non-suspendable nature of this right is underscored in Article 44, which imposes a positive obligation on States bordering straits not to “hamper transit passage” and explicitly provides that “there shall be no suspension of transit passage.” This clause is of cardinal importance. It reflects a deliberate departure from the regime of innocent passage applicable in territorial seas under Article 25(3), where suspension is permissible under certain conditions. By contrast, in the context of international straits, the drafters of UNCLOS chose to prioritize the uninterrupted flow of navigation over the discretionary authority of coastal States.
Iran
It is against this doctrinal backdrop that the current conduct of Iran must be evaluated. The imposition of a regime whereby vessels are required to seek authorization, coupled with the selective denial of passage to ships associated with adversarial States, appears prima facie inconsistent with the obligations enshrined in Articles 38 and 44. The requirement of prior authorization, in particular, has long been regarded as incompatible with the concept of transit passage, which is intended to be exercised as of right and without the need for coastal State consent.
Iran might, however, seek to justify its actions by invoking Article 42 of UNCLOS, which permits States bordering straits to adopt laws and regulations relating to transit passage in respect of, inter alia, the safety of navigation, the regulation of maritime traffic, and the prevention of pollution. Yet, Article 42(2) imposes a crucial limitation: such laws and regulations “shall not discriminate in form or in fact among foreign ships” and shall not have “the practical effect of denying, hampering or impairing the right of transit passage.” The selective nature of Iran’s measures—distinguishing between “friendly” and “enemy” vessels—raises serious doubts as to their compatibility with this provision. Discrimination, whether overt or implicit, strikes at the very heart of the legal regime governing international straits.
The legal analysis becomes more complex when one introduces the dimension of armed conflict. UNCLOS, as a comprehensive codification of the law of the sea, is conspicuously silent on the question of its applicability in times of war. There is no provision within the Convention that expressly suspends its operation or subordinates its rules to the law of armed conflict. This silence, however, should not be misconstrued as an absence of legal guidance. Rather, it reflects the broader structure of international law, wherein multiple regimes coexist and are applied in a complementary or, at times, hierarchical manner.
Article 293(1) of UNCLOS provides that courts and tribunals having jurisdiction under the Convention shall apply not only UNCLOS but also “other rules of international law not incompatible with this Convention.” This provision serves as a juridical bridge, allowing for the incorporation of the law of armed conflict at sea into the interpretative framework of the Convention. Instruments such as the San Remo Manual on International Law Applicable to Armed Conflicts at Sea, while not binding per se, reflect customary international law and provide authoritative guidance on the conduct of hostilities at sea.
Under the law of armed conflict, belligerent States possess certain rights that may, in practice, affect navigation. These include the right to establish blockades, to visit and search neutral vessels, and, under specific conditions, to capture or destroy enemy shipping. However, these rights are not unfettered. A blockade, for instance, must comply with stringent requirements: it must be declared and notified, it must be effective, it must not bar access to neutral ports and coasts, and, crucially, it must be applied impartially to all vessels, irrespective of nationality.
It is precisely this requirement of impartiality that casts a long shadow over the legality of Iran’s current conduct. A regime that permits the passage of “friendly” vessels while excluding “enemy” ships does not conform to the classical definition of a lawful blockade. Instead, it resembles a form of selective interdiction that lacks a clear basis in the established principles of naval warfare. Such selectivity risks undermining not only the rights of the affected States but also the broader integrity of the legal order governing maritime conduct.
Furthermore, even within the context of armed conflict, the strategic importance of international straits has led to a general reluctance to permit their closure. The uninterrupted flow of navigation through such chokepoints is not merely a matter of commercial convenience; it is a cornerstone of global stability. Any attempt to restrict access, particularly on a discriminatory basis, carries with it the potential for escalation, inviting countermeasures and, in extreme cases, the use of force to ensure the continuation of transit.
Iran might also seek to invoke the inherent right of self-defense under Article 51 of the Charter of the United Nations. This argument, while not without merit, must be approached with caution. The exercise of self-defense is subject to the principles of necessity and proportionality. Measures taken in self-defense must be directed toward repelling an armed attack and must not exceed what is reasonably required to achieve that objective. The blanket or selective restriction of navigation through a strait raises questions as to whether such measures can be justified as necessary and proportionate responses to specific threats.
Application of UNCLOS
The interplay between UNCLOS and the law of armed conflict thus reveals a complex and, at times, uneasy relationship. The Convention does not cease to apply in times of war; rather, its provisions are interpreted in light of, and occasionally tempered by, other applicable rules of international law. This does not, however, grant States carte blanche to disregard their obligations under UNCLOS. The regime of transit passage, with its emphasis on non-discrimination and non-suspension, retains its normative force, even in the context of armed conflict.
The situation in the Strait of Hormuz also raises broader questions about the resilience of international legal regimes in the face of geopolitical tensions. The Convention represents a delicate balance between the rights of coastal States and the interests of the international community. Any unilateral departure from this balance risks triggering a cascade of similar actions elsewhere, leading to a fragmentation of the legal order and a reversion to a more anarchic system of maritime governance.
In reflecting upon these developments, one is reminded of the enduring insight that international law is, at its core, a system of consent. Its effectiveness depends not only on the clarity of its rules but also on the willingness of States to abide by them, even when doing so may appear to conflict with their immediate interests. The selective restriction of transit passage in the Strait of Hormuz represents a departure from this ethos, substituting unilateral discretion for collective obligation.
Yet, it would be overly simplistic to characterize this development as a mere violation of legal norms. It is, rather, a manifestation of the inherent tension between law and power—a tension that has shaped the evolution of international law from its earliest beginnings. The challenge, therefore, is not merely to condemn or justify specific actions but to understand the underlying dynamics that give rise to them.
In the final analysis, the Strait of Hormuz stands as a microcosm of the broader challenges facing the law of the sea. It is a space where sovereignty and freedom, security and commerce, law and power intersect in ways that defy easy resolution. The actions of Iran, viewed through the lens of UNCLOS, raise serious legal concerns, particularly with respect to the principles of non-discrimination and non-suspension of transit passage. At the same time, they highlight the limitations of existing legal frameworks in addressing the complexities of modern conflict.
The enduring question, therefore, is whether the normative edifice of UNCLOS can withstand the pressures of contemporary geopolitics, or whether it will require adaptation and reinterpretation to remain relevant. One might conclude that the answer lies not in the abandonment of legal principles but in their reaffirmation, coupled with a pragmatic recognition of the realities that States face. The law of the sea, like the oceans it seeks to regulate, must be both stable and dynamic, capable of absorbing shocks without losing its essential character. The events in the Strait of Hormuz serve as a poignant reminder of this delicate balance, and of the enduring importance of law as both a guide and a constraint in the conduct of States.
My Tak
Any serious appraisal of the legality of Iran’s current conduct in the Strait of Hormuz must end with a candid recognition of the juridical asymmetry that underlies the entire discourse. It is not sufficient to invoke the United Nations Convention on the Law of the Sea as though it were a universally binding constitutional instrument of the oceans; nor is it intellectually honest to dismiss it merely because certain pivotal actors have chosen to remain outside its formal embrace. The truth, as is often the case in international law, lies in a more nuanced interstitial space between treaty obligation and customary norm.
Of the three principal actors whose conduct shapes the legal character of the Strait, only Oman is unequivocally bound by UNCLOS as a matter of treaty law. Its ratification imports into its legal system the full panoply of obligations contained in the Convention, including the regime of transit passage through straits used for international navigation. By contrast, Iran, although a signatory, has not ratified the Convention, and therefore is not formally bound by its provisions qua treaty. Yet, by virtue of its signature, Iran is constrained by the elementary principle embodied in Article 18 of the Vienna Convention on the Law of Treaties, namely that it must refrain from acts which would defeat the object and purpose of the Convention. This is not an insignificant obligation; it imposes a negative duty that, in the present context, raises serious questions as to the permissibility of measures that would effectively undermine the regime of transit passage.
The position of the United States is even more paradoxical. It is neither a party to UNCLOS nor bound by it as a treaty, yet it has consistently asserted that the navigational provisions of the Convention—particularly those relating to transit passage—reflect customary international law and are therefore binding on all States. This position is not merely rhetorical; it is operationalized through the United States’ Freedom of Navigation Program, which seeks to challenge what it perceives as excessive maritime claims. The United States, in effect, accepts the benefits of UNCLOS without assuming its formal burdens, a stance that has been both defended as pragmatically necessary and criticized as normatively inconsistent.
The consequence of this tripartite divergence is that the legal regime of the Strait of Hormuz cannot be understood solely in terms of treaty law. It must instead be viewed through the prism of customary international law, that elusive yet indispensable source of legal obligation derived from general and consistent State practice accompanied by opinio juris. In this regard, there is substantial, though not uncontested, support for the proposition that the core elements of the transit passage regime have attained customary status. The consistent practice of States in allowing navigation through international straits, coupled with the widespread acceptance of the principles codified in UNCLOS, lends credence to this view. Indeed, even States that are not parties to the Convention, including the United States, have acted in a manner consistent with its navigational provisions.
However, it must be acknowledged, with intellectual honesty, that this proposition is not universally accepted. Iran has persistently objected to the automatic application of the transit passage regime, maintaining that such rights are contractual in nature and therefore accrue only to States parties to UNCLOS. This position, while arguably at odds with the prevailing trend in State practice, cannot be dismissed out of hand. It reflects a deeper contestation over the nature of customary law itself—whether it can crystallize in the face of persistent objection, and whether a State that has consistently resisted a norm can be bound by it.
What emerges, therefore, is a legal landscape characterized not by clarity but by contestation. The Strait of Hormuz is geographically a strait used for international navigation, and functionally a global commons through which the lifeblood of the world economy flows. Legally, it is enveloped within the territorial seas of Iran and Oman, yet subject—at least in principle—to a regime that prioritizes the rights of the international community over the prerogatives of coastal sovereignty. This duality is the essence of the law of the sea: a constant negotiation between control and access, between the centripetal pull of sovereignty and the centrifugal demands of global interdependence.
In the present circumstances, Iran’s assertion that only “non-hostile vessels” may transit the Strait, subject to its authorization and regulatory framework, represents a fundamental departure from the universality inherent in the concept of transit passage. It introduces a criterion—political alignment—that is alien to the legal regime envisaged by UNCLOS and, arguably, to customary international law as well. Transit passage, by its very nature, is indifferent to the identity of the vessel or the policies of its flag State; it is a right grounded in the functional necessity of maintaining open sea lanes.
Yet, to characterize Iran’s position as purely unlawful would be to overlook the structural ambiguities that pervade the legal framework. The absence of universal ratification of UNCLOS, coupled with divergent interpretations of customary law, creates a space within which competing legal narratives can coexist. Iran invokes sovereignty and security; the United States invokes freedom of navigation; Oman, bound by treaty, occupies a more constrained position. Each of these positions finds some support within the fragmented corpus of international law, and none can claim absolute normative supremacy.
It is in this context that one must ultimately locate the status of the Strait of Hormuz in international law. It is, in formal terms, an international strait governed by a hybrid regime composed of treaty obligations (binding on Oman and most of the international community) and customary norms (binding, though contested, upon all States). The right of passage through the Strait—whether characterized as transit passage or, in Iran’s lexicon, a form of conditioned innocent passage—remains the central legal issue, and one that is far from settled.
The deeper implication of this analysis is that the law of the sea, for all its sophistication, remains vulnerable to the vicissitudes of power politics. Its effectiveness depends not only on the clarity of its rules but also on the convergence of State practice and belief. Where such convergence is absent, as in the case of the Strait of Hormuz, the law does not disappear, but it becomes attenuated, contested, and, ultimately, contingent.
Thus, the current situation may be seen as a manifestation of what might be termed the “relativity of legal obligation” in international law. The Convention provides a framework; customary law seeks to universalize it; State practice tests its limits. The Strait of Hormuz, in this sense, is not merely a geographical chokepoint but a juridical crucible, in which the enduring tensions between sovereignty, security, and the common interest of humanity are brought into sharp and often uncomfortable focus.
