CHOKE POINT DIPLOMACY: THE LEGAL UNCERTAINTIES BEHIND STRAIT CLOSURES AND AMBIGUITIES IN UNCLOS FOR EFFECTIVE DE-ESCALATION

By Vishesh Tiwari, a 2nd-year law student pursuing B.A. LL.B. (H) from Dr. Ram Manohar Lohia National Law University (RMLNLU), Lucknow and Shivansh Singh, a 2nd-year law student pursuing B.A. LL.B. (H) from Integrated Law Course (ILC), Faculty of Law, University of Delhi

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INTRODUCTION

The impact of the Middle East’s recent conflict resonated across global energy markets when the Iranian Parliament, in retaliation for Israel’s pre-emptive strike on its nuclear facilities, passed a resolution to close the Strait of Hormuz. Although the decision was ultimately overruled by Iran’s Supreme National Security Council, the proposal alone was enough to disturb markets. The significance of this narrow waterway, through which around 20% of the world’s oil and gas transits daily, cannot be overstated. The prospect of its closure sparked several pressing questions within the framework of international maritime law.

This blog aims to analyse two critical questions: First, whether international maritime law confers legal authority on any state to shut down a strategically important strait such as the Strait of Hormuz under any circumstances, or is it specific to some states? Second, if such a closure were to take place, what mechanisms exist under international law to challenge and resolve such an action, and what are their limitations?

THE ILLUSION OF FREE PASSAGE: LEGAL PROTECTIONS THAT BARELY HOLD

Article 45 of the UNLCOS provides for the “regime of innocent passage across the straits”. It imposes certain limitations on the right to innocent passage as provided in Article 19 of UNCLOS. Therefore, a passage across a strait is deemed to be innocent when it is “not prejudicial to the sovereignty (peace, good order or security) of the coastal state”. However, what is prejudicial is largely contextual and interpretive in its scope and depends on the manner and purpose of the passage.

UNCLOS enlists passages that threaten the sovereignty, territorial integrity or political independence of the coastal State, including exercises and practices using weapons as prejudicial and non-innocent (Art. 19 2(a to f)). Furthermore, Article 19(2)(l) includes a catch-all clause, "any other activity not having a direct bearing on passage", that could be interpreted expansively, allowing coastal states to claim a threat based on vague or unsubstantiated grounds.

Even after the postulation of the aforementioned criteria to determine the legitimacy of an innocent passage, there exist large gaps in the interpretation of the provision. This interpretive vagueness introduces an element of legal uncertainty, as actions considered benign by one state may be seen as threatening by another. Therefore, there might arise a scenario wherein a purportedly innocuous transit of an industrial substance might be perceived by the territorial state as a passage infringing its sovereignty, and there doesn’t exist any concrete test to assess the genuineness of such claims in customary international law.

Additionally, there exists no conceptual clarity to define what comprises “any act of propaganda aimed at affecting the defence or security of the coastal State” as given in Article 19.2(d).

Article 19.2 is limited in referring to non-innocent "activities," which implies that it is the conduct of the ship, and not conditions like poor maintenance, faulty equipment, or dangerous cargo, that can render its passage non-innocent. Thus, the condition-centric gaps in UNCLOS allow the coastal States to take action against any ship whose presence is perceived as a danger by the coastal state by virtue of its conduct. Likewise, UNCLOS overlooks several crucial inquiries in regards to the innocent passage, such as the determination of the extent of innocent passage for any ship. The customary international law tests the innocence of the passage by the manner of the passage instead of questioning of passage itself.

HOW COASTAL STATES CAN STILL CLOSE THE DOOR

Article 25 guarantees to the coastal states the power to protect themselves against passages across their territorial sea that are not innocent: Art. 25.1 states that the coastal state can take all appropriate measures to prevent any passage that may be “prejudicial” to its interests. Art. 25(3) guarantees the coastal state’s power to suspend innocent passage of foreign ships in some portions of its territorial sea when required for the purposes of maintaining its security. Suspension of passage takes effect only after the provision of sufficient notification.

It is important to highlight that UNCLOS creates two brackets of laws to protect against suspension of passages, categorising the innocent passage of a) commercial ships and b) non-commercial ships (either government ships or warships). Articles 29 to 32 deal with the contingencies governing them. Therefore, a commercial ship under ordinary circumstances can’t be barred from innocent passage unless it tends to jeopardise the safety of the coastal state. Thus, Iran could not have restricted the commercial passages through the Hormuz Strait that would be classified as innocent passages owing to these provisions. However, in the case of an arbitrary suspension, the dispute resolution mechanism of UNCLOS remains inadequate to mitigate the crisis that would follow.

WHY UNCLOS DISPUTE MECHANISMS CAN’T STOP A CRISIS

In case of disputes, UNCLOS provides a resolution mechanism to encourage constructive dialogue for its effective resolution. Part XV of UNCLOS provides for the “settlement of disputes" under the treaty.  Article 279 outlining “obligation to settle disputes by peaceful means” states that “any dispute should be settled by peaceful means in accordance with Article 2, paragraph 3 (peaceful settlements of disputes), of the Charter of the United Nations and Article 33, paragraph 1, of the Charter” (solution by negotiation, enquiry, mediation, conciliation, arbitration, etc.). 

Article 281 of UNCLOS provides “procedure, where no settlement has been reached by the parties”.  Article 286 provides for the compulsory procedures with the objective of achieving a binding decision when disputing states fail to reach a settlement.  Pursuant to this, Article 287.1 then enlists the “Choice of procedure (International Tribunal for the Law of the Sea, International Court of Justice, Arbitral Tribunal, constituted according to Annexe VII and VIII of UNCLOS)” for the parties to resolve the dispute, entailing a binding outcome. Thus, the outcome of the resolution process has to be duly followed by the disputing parties.  

Article 293 provides that appropriate tribunals governing under UNCLOS have the power to decide a case ex aequo et bono (deciding a case based on what is considered fair and just, even if it deviates from strict legal rules), if the parties so agree (clause 2).

In regard to the dispositive value of the tribunal's verdict, Article 296 (1) states that the decision rendered by the governing forum “shall be final and shall be complied with by all the parties to the dispute”. However, paragraph 2 of Article 296 explains that such a decision would only have a “binding force limited between the parties” and that too, to the extent of the impending dispute.  

This highlights an ambiguous aspect in regards to the current question, i.e., if any tactile act by a coastal state interferes with the passage of ships across transnational straits, as it was threatened by Iran in the case of the Hormuz Strait, who would raise a dispute, as such an obstruction would naturally affect more than one party. UNCLOS doesn’t provide any clarity regarding whether the states whose ships have been immediately restricted are a party to the dispute or whether any prospective party is allowed to raise the query.

Moreover, UNCLOS doesn’t clarify the extent of enforcement of such judgments. If it is limited only to the parties of the dispute, it would require every state party affected by such imposition to seek a judicial remedy separately, which would be highly inefficient. Conversely, if the extent of the binding judgment is interpreted to have a precedential scope, with its application extended to all the concerned parties to the extent of the dispute, it would vitiate Article 296(2), which limits the ambit of the binding decision between the disputing parties. Moreover, if the judgements are granted a wide-reaching value, whether they would have any limitation in regard to the time or scope or would they include anything under the sky (for instance, would a decision rejecting the obstruction of a strait be limited to state parties for a limited period of time or would persist till perpetuity covering even the non-state adversary?), the UNCLOS does not contemplate such considerations.

CONCLUSION

Thus, it seems that the UNCLOS’s regime of transit passage does not confer authority on any state to block a strategically important strait. Yet, the authoritative value of UNCLOS is on a voluntary basis, where it is up to the parties to decide if they comply with UNCLOS or not. Furthermore, the dispute resolution mechanisms under UNCLOS, while robust in theory, suffer from key limitations that offer no guarantee of timely or enforceable outcomes, and their judgments often lack broader applicability beyond the immediate parties.

In high-stakes scenarios like a Hormuz closure, where multiple countries are affected and swift responses are needed, these shortcomings can have far-reaching economic and geopolitical consequences. Thus, while UNCLOS provides a strong normative framework against unilateral strait closures, its interpretive gaps and enforcement weaknesses suggest that the international community must also rely on diplomacy, economic pressure, and, if necessary, collective action to uphold maritime order.