How stateless vessels challenge maritime order under UNCLOS?

By Argenis Rodriguez, maritime lawyer

Part 2

While international law clearly establishes the obligation for vessels to have a nationality, it remains largely silent on the legal consequences faced by ships that fail to meet this fundamental requirement.

It is no surprise that neither UNCLOS, nor the rest of the rules of public international law, expressly address the possible legal consequences to which a ship sailing without a flag may be subject. Anderson illustrates this plainly:

“The international law of the sea is conspicuously silent on the issue of stateless vessels, because the entire legal regime of the high seas is predicated on the assumption that every vessel has a nationality. The possession of a nationality is so essential to a vessel engaged in legitimate trade that many commentators simply could not envision a vessel not being properly registered in some country.”¹

The United Nations Office on Drugs and Crime (UNODC) states that there is no clear answer to the question whether the boarding State can assert jurisdiction over a stateless vessel, in accordance with international law. There are two main positions regarding this matter:

“(a) Some States may determine that they can, in effect, treat the vessel as one of the boarding State’s own nationality. As a consequence, the boarding State may claim that it can assert the same jurisdiction over the suspect vessel as it could assert over a vessel of its own nationality;

(b) Other States may be of the view that the statelessness as such of the vessel does not suffice in order to assert jurisdiction over the vessel and the persons on board. Accordingly, they would assert jurisdiction only if there is some other jurisdictional link with the activity of the vessel or the persons concerned (see relevant jurisdictional bases listed above).

In any case, it should be noted that, apart from the boarding State, the States of the respective nationalities of the persons on board a vessel without nationality also have jurisdictional powers over those persons – and also standing in respect of any violation of international law against them.”²

H.E. Anderson III holds that the boarding State should have a nexus to assert its jurisdiction over a vessel without nationality:
“The conclusion that a vessel may be seized by the first nation, person or persons having nationality does not necessarily follow from the premise that a stateless vessel enjoys no protection of international law. Regardless of the lack of standing of any other nation to raise a defense, the action of seizure and forfeiture are arguably illegitimate without some connection between the seizing state and the vessel or a compelling reason under national or international law (…). A state should have some nexus or, alternatively, be able to articulate an exigent circumstance for assuming jurisdiction over the vessel.”³

In the author’s opinion, a stateless vessel is not under the protection of any State. Therefore, it can be not only boarded but also seized at the discretion of the boarding State, in accordance with Article 110 of UNCLOS. Indeed, by seizing a stateless vessel, the boarding State is not violating the right of navigation of any other State, since that vessel is not under the protection of any State in the first place. Therefore, a violation of public international law in this case is unlikely.

In this regard, Anderson cites an excerpt from the case of Molvan v. Attorney General for Palestine:
“… [F]reedom of the open sea, whatever those words may connote, is a freedom of ships which fly, and are entitled to fly, the flag of a State which is within the comity of nations. No question of comity nor of any breach of international law can arise if there is no state under whose flag the vessel sails. Their Lordships would accept as a valid statement of international law, the following passage… ‘In the interest of order on the open sea, a
vessel not sailing under the maritime flag of a State enjoys no protection whatsoever, for the freedom of navigation on the open sea is the freedom for such vessels only as sail under the flag of a State”.⁴

Additionally, according to the International Maritime Organization’s Legal Committee, a stateless ship, in accordance with international law, is legally unprotected and it may be seized.⁵

This is the most logical conclusion and the one most consistent with maintaining order in the oceans. If it were accepted that a stateless vessel was untouchable simply because UNCLOS does not establish an express power in favor of the boarding State to seize that vessel, then it would be very easy to avoid accountability by simply depriving the vessel of nationality, whether through false documentation, the use of more than one flag at will, or any other scheme.

Another action that the State exercising the right of visit could take, as an alternative to seizing the vessel, would be to allow the stateless vessel to continue on its course to the port of its intended destination, but immediately notifying the authorities of that Port State of the vessel’s irregular status, so that they may thoroughly investigate the vessel and take any measures they deem appropriate once the ship is in port. This alternative would be particularly viable when the boarding State has no tangible interest in exercising its jurisdiction over that vessel.

In any case, the crew of a warship, upon discovering that a vessel is sailing on the high seas without a nationality, should under no circumstances overlook this situation. If they do not wish to seize the vessel for any reason they deem legitimate, they should inform the Port State, or any other State the warship’s crew considers appropriate.
However, seizing a stateless vessel is one thing, and what the boarding State does with that vessel once it has effectively brought it under its jurisdiction is quite another. In conducting the relevant investigations, that State must always respect the human rights of the crew, especially the right to due process. While the fact that a vessel sails without a flag may constitute an indication of an illicit or irregular activity, it will be necessary to determine whether the crew actually participated in an illicit activity and to what extent.

If the seized vessel is carrying cargo on board, in principle it should not be seized or confiscated by the authorities of the State that made the arrest, unless that cargo comes from a criminal act or serves as a tool for the transport of illicit cargo, such as drugs or weapons of mass destruction.
In the author’s opinion, if the crew and cargo are not involved in any criminal activity, the vessel should only remain arrested while it remedies its statelessness and validly acquires a nationality and statutory certificates which demonstrate that the vessel complies with the safety conditions required by international maritime conventions.

The lack of explicit regulations regarding actions to be taken against a stateless vessel stems from the fact that, as a general rule, all vessels must have a nationality. For the international community, it is simply inconceivable that a vessel sails without the protection of any State.
The author’s position is quite clear. A vessel without nationality has lost all possibilities of being protected by any State; it has disappeared from the radar of all sovereign States. Furthermore, the vessel’s lack of nationality constitutes an indication that it may be involved in illegal activity or, at best, that the shipowner has been excessively negligent and such inaction caused the vessel to lose its registration and nationality.

Therefore, a warship of any State may exercise the right of visit over such vessel and subsequently seize it, without this constituting a violation of international law, since the right of navigation of no sovereign State is being violated. Of course, this does not preclude the crew and cargo on board from being treated with due consideration, especially the crew members, who may invoke the protection of their home States.

Finally, regardless of whether or not the seizure of vessels without nationality is permissible, I believe the most important thing is that Port States ensure that no vessel sails from their jurisdictions without first verifying that it has a validly acquired flag and complies with all other international maritime regulations; a vessel sailing without being subject to the sovereignty of any State constitutes a very serious irregularity that must be prevented by States.

Andrew Anderson: Jurisdiction over Stateless Vessels on the High Seas: an Appraisal Under Domestic and
International Law, p. 334. Available : https://docs.rwu.edu/cgi/viewcontent.cgi?article=2367&context=law_ma_jmlc ↩︎
United Nations Office on Drugs and Crime (UNODC): Maritime crime: a manual for criminal justice practitioners – Third edition, p. 186. ↩︎
Anderson III, H., Edwin: “The Nationality of Ships and Flags of Convenience: Economics, Politics and Alternatives”, cit., pp. 142-143, cited by Domínguez Cabrera, María del Pino. Accessed on January 28, 2026. Available: https://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-09502005000100005#26 ↩︎
Andrew Anderson: Jurisdiction over Stateless Vessels on the High Seas: an Appraisal Under Domestic and
International Law, pp. 336-337. ↩︎
International Maritime Organization’s Legal Committee: Final Report of the Study Group on Fraudulent
Registration and Fraudulent Registries of Ships, p. 15, paragraph 19. Available: https://wwwcdn.imo.org/localresources/en/MediaCentre/MeetingSummaries/Documents/FINAL%20REPORT%20-
%20Study%20Group%20on%20Fraudulent%20Registration%20and%20Fraudulent%20Registry.pdf ↩︎