Reaction to “Can Coastal States Interrupt Foreign Passage in Their Territorial Seas in Response to Non-Compliance with Human Rights Obligations? A Response to the ASCOMARE Legal Opinion”

[The Legal Opinion Expert Group:

Ademuni Odeke is a professor of international maritime law and policy and special advisor to the National Centre for the Sea and Maritime Law, at the Department of Maritime Law, University of Ankara (Türkiye).

Alice Ollino is an assistant professor in international law and ricercatore at the University of Milano-Bicocca (Italy).

Andrea Caligiuri is an associate professor of international law and director of CiRAM (Centro interdipartimentale di Ricerca sull’Adriatico e il Mediterraneo) at the University of Macerata (Italy).

Andrea Pappalardo is an international lawyer and founding partner of Iustopia Law Firm in Geneva (Switzerland).

Daud Hassan is a founding director of the International Centre for Ocean Governance, adjunct professor at the Western Sydney University (Australia) and professor of law at Jindal Global University (India).

Irini Papanicolopulu is global professor of international law at SOAS University of London (UK).

Pierandrea Leucci is director of ASCOMARE, legal officer, lecturer in the law of the sea, and editor-in-chief of the Yearbook on the Law of the Sea. The views expressed in this legal opinion are solely those of the author and do not represent the positions of the institutions with which the author is affiliated or any associated parties.

Tullio Scovazzi is a former professor of international law at the University of Milano-Bicocca (Italy) and a member of the Institut de Droit International.]

We appreciate the engagement with the recent ASCOMARE Legal Opinion (‘the Opinion’) and welcome critical discussion on the scope and limits of coastal State authority under international law. However, certain aspects of the analysis presented by Eduardo Cavalcanti de Mello Filho in the piece published on Opinio Juris on 1 May 2025—entitled “Can Coastal States Interrupt Foreign Passage in Their Territorial Seas in Response to Non-Compliance with Human Rights Obligations? A Response to the ASCOMARE Legal Opinion” (‘the Response’)—warrant clarification. In particular, several interpretations drawn from the Opinion appear to oversimplify complex legal arguments and to assess specific points in isolation from the broader legal and factual context that justified the issuance of the Opinion.

This appears already from the response’s introductory remarks, which question the Opinion’s conclusion that the passage of vessels transporting weapons to Israel may be deemed non-innocent under the UN Convention on the Law of the Sea (UNCLOS) and “other rules of international law”, in accordance with Article 19(1). The concern raised—that such an approach could result in “thousands of ships” being classified as engaging in non-innocent passage due to “minor inconsistencies with human rights obligations”—ignores that the situation at the background of the Opinion is not one of “minor inconsistencies with human rights obligations”, but rather one of grave, continuing, and extensive breaches of fundamental and peremptory rules of customary international law. As clearly stated in paragraph 54 of the Opinion, the legality test under Article 19(1) must be applied on a case-by-case basis, taking into account factors such as the normative status of the breached obligation (e.g., whether it constitutes jus cogens) and the specific legal instrument from which the coastal State’s duty arises in relation to UNCLOS. This qualification is central to the Opinion’s findings and would, by its very nature, preclude any automatic (by-default) classification of passage as non-innocent. Unfortunately, these clarifications and references are not acknowledged in the response.

The following reaction seeks to engage with some of the central claims made in the response that, in our view, warrant closer scrutiny and elaboration. 

Framing the Problem 

The legal opinion commissioned by the Palestinian BDS National Committee and prepared by ASCOMARE—bringing together the expertise of international law experts and researchers specializing in various aspects of the law of the sea—addresses two overarching questions, each subdivided into several key components. The response seems to focus on sub-question (a)(i) of Question 1 and is therefore selective in its engagement with the broader analysis offered in the Opinion.

This sub-question addresses, inter alia, the compatibility between a coastal State’s obligations under Part II, Section 3 of the UNCLOS, which governs the regime of innocent passage, and other binding international obligations applicable within its territorial sea. These include duties arising under instruments such as the UN Arms Trade Treaty (ATT), the Convention on the Prevention and Punishment of the Crime of Genocide (Genocide Convention), and the International Convention on the Suppression and Punishment of the Crime of Apartheid (Apartheid Convention). At its core, the question concerns whether—and to what extent—a coastal State may, or is required to, take action, including proportionate and necessary enforcement measures, against foreign vessels exercising passage in its territorial sea while engaging in conduct that is prejudicial to its peace, security, or good order, or that otherwise constitutes a breach of international obligations to which the State is subject.

It is crucial to emphasize, however, that sub-question (a)(i) must not be considered in isolation from sub-question (a)(ii), which examines the jus cogens nature and legal consequences of violations of certain norms embedded in the aforementioned legal instruments and the UN Charter. The response, however, appears to address these two elements separately and only occasionally engages with them in tandem.

For instance, it is unclear why the response challenges the applicability of Article 19(1) of UNCLOS in relation to the coastal State’s human rights obligations, while overlooking the central focus of the Opinion’s analysis under Article 19(1)—specifically, the implications of non-compliance with peremptory norms of international law, such as those enshrined in the Genocide Convention, the Apartheid Convention, and the UN Charter. Aside from the specific points raised in the response, which will be examined in detail below, we submit that a holistic reading of the Opinion is essential to ensure an accurate understanding of its conclusions and to prevent any misrepresentation of its legal reasoning.

Article 19(2)(a), UNCLOS

The principal comments made in the response with respect to the Opinion’s interpretation of Article 19(2)(a) may be summarized as follows:

The Purported Prioritization of a “Subjective” Standard over an “Objective” One

Relying on a 1984 quotation from Oxman, the response appears to advocate for an “objective” standard in identifying prejudicial conduct of a vessel, seemingly suggesting that the Opinion adopts an overly “subjective” reading of Article 19(2)(a). It is, however, unclear where this dichotomy emerges from the Opinion itself. On the contrary, the Opinion explicitly requires an active form of conduct by the vessel as a precondition for non-innocent passage, as set out in paragraphs 43–44 and 46–47.

If the critique aims to distinguish between “subjective” and “objective” types of activities, this approach remains conceptually and practically challenging, particularly given that activities under Article 19(2) are already framed in legally defined terms. A more appropriate and workable distinction, reflected in the Opinion and supported in literature, is that between active and passive behaviour. In this context, the Opinion’s conclusion in paragraph 47 is that “complicity” may amount to a “legally recognized act under international law”, and that the “threat of force” may be established through a “declaration of intent or conduct that reasonably conveys the likelihood of force being used”—criteria that align with an “objective” rather than a “subjective” qualification of the conduct. Far from contradicting the Opinion, the response’s concerns appear largely consistent with the legal reasoning advanced in it.

The Alleged Discriminatory Nature of Suspending Passage Under Article 19(2)(a)

The response further infers that applying the Opinion’s analysis to vessels transporting arms or illicit materials to a specific destination—such as Israel—would contravene the non-discrimination obligations enshrined in UNCLOS, particularly Article 24. This critique appears to conflate the destination of the vessel with its conduct within the territorial sea.

However, the Opinion is clear in establishing that the legal basis for suspension lies in the vessel’s conduct—namely, its involvement in activities prejudicial to the peace or security of the coastal State—rather than the identity of the recipient State. 

That multiple vessels may be heading to the same destination is legally immaterial where each independently breaches international norms, such as those found in Article 6 of the ATT or in jus cogens obligations. The enforcement action is thus grounded in the conduct and its legal consequences—not in discriminatory targeting. 

Finally, the response’s categorical dismissal of the customary status of Article 24 of UNCLOS appears to give too much weight to interpretations dating back to times when the law of the sea was still evolving and not to take sufficiently into account the practice of States since the entry into force of UNCLOS. It thus diverges from established scholarly assessments, which have recognised this provision as reflecting customary international.

The Scope of Coastal State Protection

The response acknowledges that Article 19(2)(a) is inherently coastal State–centric, in that it requires a threat or use of force against the coastal State. However, the critique does not adequately engage with the broader legal implications of this standard, particularly with respect to the coastal State’s own potential responsibility under international law (a clear coastal State’s interest to be protected). 

In fact, as the Opinion outlines in paragraphs 55 to 66, a coastal State’s failure to take action in response to violations of binding international norms—particularly those of a peremptory nature—may give rise to international responsibility for complicity or omission. Thus, even within the narrow scope of Article 19(2)(a), the coastal State’s interest in preventing non-innocent passage should extend to obligations to prevent the commission or facilitation of serious international crimes, particularly where such conduct implicates the State’s own legal duties or may trigger its international responsibility. The responsibilities of coastal States are dual in nature: the protection of national security and the fulfilment of treaty-based and customary international law obligations. These duties are inherently interconnected. In this respect, the concerns articulated in the response appear to reinforce—rather than contradict—the core findings of the Opinion.

Article 19(1), UNCLOS

The response begins by acknowledging the interpretive ambiguity of the phrase “other rules of international law” in the second clause of Article 19(1) of UNCLOS. It then questions whether this formulation, standing alone, can serve as a sufficient legal basis to render a vessel’s passage non-innocent, including in cases of non-compliance with human rights obligations binding upon the coastal State—an approach broadly consistent with the Opinion’s findings. 

However, the response ultimately appears to dismiss this possibility without providing a sufficiently substantiated justification. Instead, it advocates for a narrower reading of Article 19(1), confining its application to rules that directly regulate the passage of ships. Yet the substantive distinction between “rules concerning the passage of vessels” and those governing conduct amounting to violations of international law—including acts of complicity or facilitation—remains conceptually unclear.

More fundamentally, and as already noted above, the Opinion does not limit the application of Article 19(1) to human rights obligations alone, but instead highlights the particular relevance of peremptory norms of international law, such as those enshrined in the Genocide Convention, the Apartheid Convention, and the UN Charter. In this regard, it is difficult to reconcile the response’s restrictive interpretation of Article 19(1)—which seemingly excludes the application of such universally binding norms—with its simultaneous openness to recognising the relevance of certain UN Security Council resolutions under the same provision. This selective interpretive approach appears inconsistent, as it assigns greater normative weight to determinations under Chapter VII of the UN Charter than to obligations arising from peremptory rules of international law, whose binding character is universally recognised, from which no derogation is permitted, and which may as well implicate the international responsibility of States in cases of non-compliance—thereby directly implicating the interests of affected States.

The exclusion of human rights considerations from the interpretative and regulatory framework of UNCLOS appears increasingly difficult to reconcile with the jurisprudential and scholarly developments of the past three decades. International courts and tribunals, including the International Tribunal for the Law of the Sea (ITLOS), have progressively embraced “considerations of humanity” as a relevant factor in the interpretation and application of the law of the sea. This evolution reflects a broader trend toward integrating human rights norms into the fabric of maritime legal reasoning. As early as 2010, former ITLOS Judge Treves observed that

[t]he resort to human rights or humanitarian considerations and rules in the context of the Law of the Sea is just at a beginning stage. Other situations may be envisaged that are neither foreseen explicitly or implicitly in the [UNCLOS] nor have been considered by international courts and tribunals.

This statement underscores the dynamic and evolving character of the law of the sea, consistent with the final preambular clause of the UNCLOS, which affirms that the Convention cannot be rigidly confined to its original textual formulation but must remain responsive to broader developments in international law.