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

[Eduardo Cavalcanti de Mello Filho is a Research Associate (Ocean Law and Policy) at the Centre for International Law, National University of Singapore]

On 11 March 2025, ASCOMARE authored a legal opinion commissioned by the Palestinian BDS National Committee, answering the above question in the affirmative. The piece is well-written and insightful, but its findings are also innovative and perhaps too far-reaching.  My aim here is to nuance its arguments regarding Article 19 of the 1982 UN Convention on the Law of the Sea (UNCLOS), on the right of innocent passage in foreign territorial seas. At the end, I present an alternative justification under which coastal States may interrupt foreign passage in the territorial sea as a response to non-compliance with human rights obligations, notably where international crimes are concerned.

Brief Highlights of the Opinion

The question of interest concerns whether coastal States may interrupt the passage of a foreign vessel through their territorial sea “in response to non-compliance with international human rights obligations binding upon those States, including obligations under the UN [2014] Arms Trade Treaty and other relevant treaties?” Against the backdrop of the Israeli-Palestinian situation, the opinion focusses on the transporting of military material to Israel, which could be reasonably believed to be used in actions classified as genocide, crimes against humanity, or war crimes.

Analyzing whether coastal States may interrupt the passage of such vessels, the opinion starts with UNCLOS Article 17, which guarantees the right of innocent passage in foreign territorial seas. The opinion then turns to Article 19, which provides for the meaning of ‘innocent’. Under Article 19(1), passage is non-innocent if “prejudicial to the peace, good order or security of the coastal State”. The opinion accepts that passage is characterized as non-innocent under Article 19(1) when a ship is engaged in an activity listed in Article 19(2).

Among the latter’s subparagraphs, it focused on ‘a’, which reads: “any threat or use of force against the sovereignty, territorial integrity or political independence of the coastal State, or in any manner in violation of the principles of international law embodied in the [UN Charter].” (Emphasis added.) The opinion then concentrated on the emphasized part, which includes, e.g., the right to self-determination. A fortiori, because Israeli military activities in the Occupied Palestinian Territories violate this right — among others — the opinion concludes that vessels carrying arms to Israel might be reasonably expected to contribute to these violations and are engaged in non-innocent passage. 

The opinion also notes that the second part of Article 19(1) determines that “[s]uch passage shall take place in conformity with this Convention and with other rules of international law.” The opinion does not specify the reach of “other rules of international law” and, considering the cargo’s prospect of being used to carry out international crimes, maintains that such a ship’s passage would be non-innocent.

The key innovations here are twofold: first, this argument focuses not on the immediate passage context in the territorial sea, but on its eventual contribution to atrocities elsewhere; second, it extends the scope of “non-innocence” beyond acts against the coastal State. Furthermore, while the opinion presents compelling literal interpretations of Articles 19, they are nevertheless unprecedented in State practice and opinio juris and could have unintended consequences. For example, if passage is deemed non-innocent whenever it does not conform “with [the] Convention and with [any] other rules of international law,” minor inconsistencies with human rights obligations could render thousands of ships’ passage non-innocent (Article 19). In the following paragraphs, I propose some nuances to these interpretations of Articles 19(1) and (2)(a).

Passage Prejudicial to the Peace, Good Order, or Security of the Coastal State — First Part, Article 19(1), as Typified in Article 19(2)(a)

As Oxman explains, “there ha[d] traditionally been disagreement as to whether innocence is to be measured solely by a ship’s conduct while in the territorial sea by the coastal State (an objective standard), or also by its flag or mission (a subjective standard).” However, he reasonably advanced that Articles 19(2) and 24(1)(b) are “decidedly influenced by an objective, rather than subjective, test for innocence.”

Notably, the “threat or use of force” is just one among several activities taking place in the territorial sea — especially subparagraph (l), which includes “any activity not having a direct bearing on passage’. Moreover, connected to the coastal State’s obligation to “not hamper the innocent passage of foreign ships through the territorial sea,” Article 24(1) privileges the objective standard, as it determines that “the coastal State shall not discriminate in form or in fact against the ships of any State or against ships carrying cargoes to, from or on behalf of any State.” Nothing in UNCLOS allows for such discrimination (e.g. towards ships transporting armaments to Israel).

Even if the subjective test were to be adopted, its focus has historically been on the coastal State’s protection from outwardly innocent foreign vessels with malicious intents. This is also true regarding uses of force “in any manner in violation of the principles of international law embodied in the [UN Charter].” 

On the one hand, this phrase replaced, in UNCLOS, the excerpt in the UN Charter Article 2(4) that reads “or in any manner inconsistent with the Purposes of the United Nations.” The latter was adopted to clarify that not only uses of force against another State in offense of its territorial integrity or political independence were illegal; other uses of force against that State could also be illegal, given, for instance, their opposition to the UN purpose of maintaining peace and security. 

On the other, “principles of international law embodied in the [UN Charter],” also found in Article 301, is a renvoi to other relevant norms not found in UNCLOS, including the right of self-defense in UN Charter Article 51 and the UN collective security system. This phrase does not deviate from the link between non-innocence and protection of the coastal State.

The Requirement that Innocent Passage Conform to UNCLOS and Other Rules of International Law — Second Part, Article 19(1)

The second part of Article 19(1) originated in the 1956 Articles concerning the Law of the Sea because “the [International Law] Commission could not possibly codify the vast number of rules, based on usage, concerning the passage of foreign ships” (CYBI, 1954). It was incorporated into the 1958 and 1982 Conventions in provisions determining when passage is innocent (Articles 14(4) and 19(1), respectively). 

Notwithstanding this, the provision’s effects are unclear. For example, do “other rules of international law” characterize passage as non-innocent or do they merely govern the conduct of foreign ships? (Article 19) It is certain, however, that they only cover “rules […] concerning the passage of foreign ships.” The better view is, therefore, that they do not include human rights obligations nor those related to international crimes.

An alternative argument based on the Corfu Channel case suggests that a coastal State must “not […] allow knowingly its territory to be used for acts contrary to the rights of other States,” which inspired Article 15 of the 1958 Convention on the Territorial Sea and the Contiguous Zone, later dropped from UNCLOS Article 24. Nonetheless, this duty would only apply to protecting the navigational rights of other States, and its absence in UNCLOS reflects concerns that it could unduly burden coastal States (Article 24) — it is not part of customary international law.

McLaughlin suggests that this reference to other rules ensures coherence with “the very wide powers that international law invokes in the name of international peace and security.” He focused on the right of self-defense and, especially, decisions of the UN Security Council under Chapter VII. Coastal States could interrupt arms shipments to Israel under a Chapter VII decision or as an act of collective self-defense upon request. However, such a decision is unlikely, and acting in collective self-defense exposes the defending State to Israeli response.

A Final Option

A final, more promising option lies in the law of state responsibility, which was not covered in the ASCOMARE opinion. An eloquent illustration of this possibility is the 2019 seizure of the Panamanian-flagged tanker Grace 1 in Gibraltar’s territorial sea.  The UK seized the vessel because it was believed to be transporting Iranian oil to Syria in breach of sanctions responding to international crimes. While this act violated the ship’s (or Panama’s) passage rights under the law of the sea, the law governing countermeasures arguably offered avenues for precluding its wrongfulness. In casu, the British action must be seen within the broader context of Western sanctions then aimed at dissuading the Assad regime from persisting in international crimes and other human rights violations. 

But this argumentative option is not without difficulties. It is questionable whether, to address the violation of erga omnes obligations, States may resort to countermeasures where they are not directly injured by the wrongful act concerned — an issue left open by Article 54 of the International Law Commission’s Articles on the Responsibility of States for Internationally Wrongful Acts (ARSIWA) . It is also unclear whether maritime law enforcement of this sort affects “the obligation to refrain from the threat or use of force as embodied in the [UN Charter],” in accordance with ARSIWA Article 50(1)(a). In any case, differently from the Grace 1 incident, interrupting arms shipments to Israel would be directly linked to the international law violations it seeks to prevent, thus also fulfilling the countermeasure requirement of proportionality.

So, the answer to the question in this piece’s title is perhaps “yes.” (It is noteworthy that the largest arms suppliers to Israel were also the States behind the Grace 1 seizure, which concerned the enforcement of US and EU sanctions — the UK only left the EU in 2020.)