Iran’s Seizure of the Two Greek-flagged Vessels: An International Law Perspective

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The Facts

On 27 May 2022 the Islamic Revolutionary Guard Corps (IRGC) announced the seizure of two Greek-flagged oil tankers, which sailed in international waters, 22 nautical miles from the Iranian coast (see here the statement quoted by the Iranian State news agency IRNA). The IRGC helicopters landed onboard the Greek vessels “Delta Poseidon” and “Prudent Warrior” and captured the crew. The ships were then directed to Iranian territorial waters, where they are currently anchored, and the crew was transported on shore, under house arrest. Both the Greek Ministry of Foreign Affairs and the Hellenic Coast Guard characterised this action as an act of piracy and protested for the seizure of the vessels (see here the official announcement of the Greek MFA and here the announcement of the Coast Guard in Greek). According to other Iranian State news agencies, the two ships were seized in retaliation for Greece’s seizure of an Iranian oil tanker near the coast of the island of Evia due to EU sanctions (see here). Other sources provide that after the seizure of the Iranian vessel, the US planned to confiscate the oil onboard and send it back to the US (see here and here).

The current contribution tries to give shape to the present incident from an international law perspective. For that, it will first try to legally characterise the Iranian actions and will then proceed to examine possible legal justifications.

The Law: Piracy vs the Principle of Exclusive Flag State Jurisdiction

As was previously mentioned, the Greek MFA characterised the Iranian acts as acts of piracy. But do they really constitute piracy?

Under Art. 101 LOSC, the act of piracy is constituted under the following conditions: first, there must be an illegal act of violence committed by the crew or the passengers of a private vessel or aircraft on the high seas. Second, the act should be committed for private ends and, third, it must be addressed towards another vessel or aircraft. Under the same conditions, an act can be considered as an act of piracy if it is committed “by a warship, government ship or government aircraft whose crew has mutinied […]” (Art. 102 LOSC). Thus, as Guilfoyle observes, “absent such mutiny public vessels cannot commit piracy. Otherwise, violence against other vessels committed by a warship is a question of State Responsibility” (A. Proelß, p. 744). It is, therefore, clear that the acts of the IRGC – as acts committed by the Iranian army – do not constitute acts of piracy under international law. However, they certainly constitute a flagrant violation of the principle of exclusive flag State jurisdiction (EFSJ).

As an “inherent component of the freedom of navigation under Art. 87 LOSC” (Paragraph 225, M/V Norstar, 2019), on the high seas the flag State has the exclusive jurisdiction over vessels flying its flag, encompassing both prescriptive and enforcement jurisdiction (Art. 92 LOSC). It is also well known that vessels are considered as a single unit, including every person onboard and regardless of their nationality (Paragraph 106, M/V Saiga (No. 2), 1999). Of course, exceptions do exist, but these solely encompass the right to visit, the right of hot pursuit or the consent of the flag State. Thus, it is evident that under the circumstances that the incident occurred, only Greek warships (and “any other duly authorized ship[s] […] being on government service”) could proceed to the seizure of the two Greek vessels, absent any exception to the principle of EFSJ. What is equally interesting under international law is the examination of the incident from the perspective of State responsibility.

Retaliation and Countermeasures: Any Ground Precluding Wrongfulness?

It is (hopefully) evident from the above analysis that Iran’s actions are in breach of the LOSC, and specifically Art. 87, in concert with Art. 92, thus entailing its international responsibility. Nevertheless, the IRGC seems to claim that its acts constitute a retaliation for Greece seizing an Iranian vessel and the oil onboard within its territorial waters (see here the quoted statement of Iran’s Supreme Leader). But could this be legally characterised as countermeasures, precluding the wrongfulness of Iran’s acts under the ARSIWA?

Art. 22 ARSIWA indeed provides that the wrongfulness of an act of a State is precluded if the act constitutes a countermeasure in accordance with the specific provisions of the Articles. Hence, Art. 49 ARSIWA becomes relevant as it specifies that countermeasures can be taken by an injured State against another State “which is responsible for an internationally wrongful act [..]” (also: Paragraph 83, Gabčikovo-Nagymaros Project case, 1997). Additionally,  “[c]ountermeasures must be commensurate with the injury suffered […]” (Art. 51) and the injured State shall call the other State to comply with its international obligations and inform about the decision to take countermeasures (Art. 52).

It becomes apparent that the main question to be answered is whether Greece’s acts were in breach of international law. Contrary to the situation in Iran, the Iranian vessel was reported to sail within Greece’s territorial waters and not on the high seas. Thus, as long as Greece has exercised its prescriptive jurisdiction to this effect and there is a legal basis under the LOSC to enforce that jurisdiction, the arrest of the vessel would be lawful. In the case at hand, Art. 27 paragraph 1(a) LOSC would suffice as the jurisdictional basis for enforcement in this regard, since it only requires the crime “[…] to disturb the peace of the country or the good order of the territorial sea”. In the alternative, one could designate this as customs violation and thus, coastal State may exercise its plenary enforcement jurisdiction (also: Paragraphs 257-260, Duzgit Integrity Arbitration, 2016).

According to the published facts, there seem to be two grounds for Greece’s acts: the first one are the EU sanctions and the second one is the Treaty on Mutual Legal Assistance between the United States and Greece (available here). On 14 April 2022, the Hellenic Coast Guard, after discovering that the Russian-flagged vessel “Pegas” was owned by the Russian company “PAO Promsvyazbank”, seized the vessel because it was subject to the restrictive measures taken by the EU against Russia. Thus, Greece was in fact enforcing the EU legislation towards Russian assets by arresting the vessel, rendering this exercise of jurisdiction reasonable.

Nevertheless, the Hellenic Coast Guard was subsequently informed that the Russian-flagged vessel “Pegas” had changed its flag to Iran and was now named “Lana” and, thus, could not be subject to EU sanctions. It is to be noted that although under the LOSC a vessel is dissuaded from changing its flag during its voyage (Art. 92 LOSC), this constitutes in fact common practice. However, this change of flag generated numerous problems. On 20 April 2022, the US requested the Greek Ministry of Justice to seize the Iranian vessel and the oil onboard on the ground that the profits from the transportation of Iranian oil “will support a foreign terrorist organization in violation of US criminal law” (see here the quoted request in Greek). Having transferred its treaty obligations arising from the aforementioned Treaty in its domestic law, Greece had once again the grounds to enforce its legislation and allow US authorities to intervene. Indeed, the Court of First Instance of Halkida issued two orders of provisional measures, prohibiting the vessel from departing the port (see here in Greek). Under these grounds, Greece’s act cannot be characterised as internationally wrongful and Iran could not invoke countermeasures as a ground precluding the wrongfulness of its own acts.

Nonetheless, even if Greece’s acts are to be considered as an unlawful exercise of jurisdiction, Iran would still have to face the proportionality test as well as the procedural requirements of adopting countermeasures. It is true that under the Law of State Responsibility, there is no requirement of reciprocity for countermeasures to be deemed proportionate, although as Crawford argues “same or similar acts are more likely to satisfy the proportionality test” (Crawford, pp 698-699). Thus in the case at hand, Iran is certainly not limited to proceed to the exact same acts as Greece. Even if we consider that the seizure of the Greek vessels is a response to the confiscation of the oil, this element alone does not render the countermeasure disproportionate. Nevertheless, proportionality is not only a question expressed in quantitative terms, but also the quality and the character of the rights are considered (Articles on State Responsibility for Internationally Wrongful Acts with Commentaries, p. 135). Thus, in the proportionality test one could argue that violating the freedom of navigation on the high seas and the principle of EFSJ is of a completely different character than the seizure of a vessel and the cargo in the territorial sea of a State. Those two principles –and especially the freedom of the high seas– constitute the cornerstone of the law of the sea since (almost) its genesis. Following that, Iran could not justify its acts as being proportional simply because Greece had proceeded in a (not really) similar act.

The procedural requirements could also be questioned. Was there any official request towards Greece to cease the “unlawful” act? Was Greece informed about the possibility of countermeasures? But those obligations could easily be set aside by invoking the “urgency of the situation” exception of Art. 52 paragraph 2 ARSIWA.

It is therefore apparent that the claim of countermeasures may not be easily successful. Of course, it remains a matter considered on a case by case basis and no definitive conclusion can be deduced in advance.

Concluding remarks

The present analysis did not aim to justify the acts of any of the two conflicting States, but rather to reason them under international law. In the recent years, there has been a rise in the number of cases involving both the freedom of navigation and the principle of EFSJ. The M/V Norstar, the Enrica Lexie incident and the San Padre Pio cases (although officially discontinued) are certainly the most common examples. Following this, the question of the legality of the seizure of the two Greek vessels could constitute a very interesting case before an international Court or Tribunal. And while the freedom of the high seas and the principle of EFSJ may not require further interpretation, a possible counterclaim on the issue of countermeasures would definitively shed light, among others, to the proportionality test.

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