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Naval Identity at Sea

Treaties and International Laws

Last modified: 2011-12-23 by rob raeside
Keywords: flags at sea | international treaties:sea | international conventions: sea |
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I am polishing up my paper for the Buenos Aires and I would like to ask for some help with quoting the sources. Here are some of my questions or statements. The straightforward answer I know as I am sure many of us do, but I miss some "hard evidence."

- what regulation/international laws/customs determine the need for national identification of a ship and what is prescribed for a ship to be considered a war ship?

- a naval ship is identified as such (i.e. differentiated from a merchant ship) by the flags its fly (and possibly other non-vexillological signs). naval ensign, jack and masthead pennant identify the naval ship and its nationality. however, jack is nowadays used only on the anchor, masthead pennant is often gone altogether or very small?

I might have a few more of this kind, but this would already help if you could point me around.
Željko Heimer, 2 June 2005

Convention on the High Seas, 1958 (article 8):

For the purposes of these articles, the term "warship" means a ship belonging to the naval forces of a State and bearing the external marks distinguishing warships of its nationality, under the command of an officer duly commissioned by the government and whose name appears in the Navy List, and manned by a crew who are under regular naval discipline.

Full text at:

Almost same definition appear in article 29 of UNITED NATIONS CONVENTION ON THE LAW OF THE SEA
Dov Gutterman, 2 June 2005

As I understand it, it is up to each country to define publicly the marks that will distinguish its warships. U.S. Navy Regulations do this for the United States Navy: "The distinctive mark of a ship or craft of the Navy in commission shall be a personal flag or command pennant of an officer of the Navy, or a commission pennant. The distinctive mark of a hospital ship of the Navy, in commission, shall be the Red Cross flag." (Article 1259)

Similarly, U.S. Coast Guard (USCG) Regulations (Article 14-8-3) say: "The distinctive marks of a Coast Guard vessel are the Coast Guard ensign and if authorized the Coast Guard commission pennant or the personal flag or command pennant of a Coast Guard officer." In the non-vexillological arena, the Code of Federal Regulations (33 CFR Pt 23) also lists the Coast Guard emblem and the so-called "racing stripe" hull marking as distinctive marks of USCG vessels.

I don't have copies readily available, but my recollection is that the British Queen's Regulations for the Navy say similar things about the White Ensign, Union Jack, and personal flags, broad pennants, and commissioning pennants. I assume other navies issue equivalent directives, just as they publish lists of commissioned officers to comply with that provision of the treaties cited above.
Joe McMillan, 2 June 2005

The Law of Nations does not include any rules regarding the claim of vessels to sail under certain maritime flag, but imposes the duty upon every State having a maritime flag to stipulate by its own Municipal Laws the conditions to be fulfilled by those vessels which wish to sail under its flag. In the interest of order on the open sea, a vessel not sailing under the maritime flag of a State enjoys no protection whatever, for the freedom of navigation on the open sea is freedom for such vessels only as sail under the flag of a State. But a State is absolutely independent in framing the rules concerning the claim of vessels to its flag. It can in particular authorise such vessels to sail under its flag as are the property of foreign subjects; but such foreign vessels sailing under its flag fall thereby under its jurisdiction.

But no State may allow a vessel to sail under its flag which already sails under the flag of another State. A vessel sailing under the flags of two different States, like a vessel not sailing under the flag of any State, does not enjoy any protection whatever. Nor is protection enjoyed by a vessel sailing under the flag of a State which has no maritime flag. Vessels belonging to subjects of such a State must obtain authority to sail under the flag of another State, if they wish to enjoy protection on the open sea. And any vessel, although the property of foreigners, which without authority under the flag of a State, may be captured by the men-of-war of such State, prosecuted, punished, and confiscated.

All States with a maritime flag are by the Law of Nations obliged to make private vessels sailing under their flags carry on board so-called ship's papers, which serve the purpose of identification on the open sea. But neither the number, nor the kind, of such papers is pre­scribed by International Law, and the Municipal Laws of the different States differ much on this subject.

Every State must register the names of all private vessels sailing under its flag, and it must make them bear their names visibly, so that every vessel may be identified from a distance. No vessel may be allowed to change her name without permission and fresh registration.

Extracts from Oppenheim's International Law edited by Lauterpact; 5th 1937.


The essential features of a warship are that her commander holds a commission from his State, the ship flies the flag of the navy which in many countries is different from that of the merchant marine, and the officers and crew are under naval discipline. There are also other vessels in all navies which act as transports, colliers, supply and dispatch ships and for other services of a public nature. They are known in the British navy as "fleet auxiliaries" but unless they are specially commissioned they are not entitled to act as warships in the exercise of hostile operations.

States Without a Sea-board.

As we have seen, a merchant ship on the high seas must possess the right to fly the flag of a particular State. Before the war of 1914-18, there was some doubt as to whether a State without a sea-board could claim the right to a maritime flag. The question was raised in Switzerland several times, but on each occasion the Swiss Federal Council declined to give permission to Swiss subjects to use the national flag at sea. They were consequently compelled to use the flag of some other State. The reasons given by those who were opposed to the use of a maritime flag by inland countries were that the ships were dependent on the goodwill of other nations for the use of their ports, and that the responsibility which results from a ship's nationality can only be real if the ship belongs to a port of a State and that on her return to that State the captain, crew and passengers could be punished for any offences they may have committed at sea. However, under the Treaty of Versailles, 1919, the High Contracting Parties agreed to recognise the flag flown by the vessels of an allied or associated, Power having no sea-board which are registered at some one specified place situated in its territory, which was to serve as the port of registry of such vessels (art. 273). The Treaty of Saint-Germain, 1919 (art. 225); the Treaty of Trianon (1920) (art, 209); and the Treaty of Neuilly (1919) (art, 158) similarly grant to all the contracting Powers the privilege of recognition of their respec­tive flags. At Barcelona the States which had participated in the Conference on Communications and Transit signed on April 20, 1921, adopted a "Declaration" which substantially incorporates the provisions contained in the Peace Treaties, by recognising the right to a flag of the vessels of States having no sea-coast which are registered at some one specified place situated in their territory; "such place shall serve as the port of registry of such vessels." The principle of the recognition of the flag of a non-maritime State has thus been accepted by a large body of Powers.

Extracts from International Law of the Sea by Higgins and Colombos, 1st 1943.

David Prothero, 3 June 2005

Reading further on the ensigns used on ships I come to a question that is not quite in any connection with the paper I am writing but may be interesting to be discussed here. It regards the so called "right of flag" i.e. who are the entities who may have a rightful ensign. It is well known that in history the right of flag was not recognized to the landlocked countries and that well into the 20th century that right was at least unclear. It was only in 1921 (Barcelona Declaration) that this right was recognized and afterwards implemented in 1958 Geneva Convention on High Seas.

However, even since it was unclear weather the international organizations (like Red Cross) or inter-state organizations (like the UN) have right to fly its ensign, i.e. to register ships under its flag. Historically, this was not quite unusual, as there were cases of trade companies and organizations like Hanza that used special flags of its organization according to special treaties and permissions. However, it seems that times have changed since, and today (at least after 1958 Convention) the right was questioned and no ships were flying the RC or UN ensigns. It was generally considered that this should not be a problem but that such organizations need to prescribe regulations regarding the criminal and civic regulations to which the ships shall adhere. This was, as I understand done so that the ships of the organizations were registered under some country's flag and therefore using it as ensign. Since the new Convention was signed in 1982 (it is said in art. 93) it is determined that international organizations have right of flag. I am not sure if until now this right is excercised and if there are any ships navigating under the ensigns of the UN or some other organization...

Well, I have written the above without any question mark, but I could have equally written it full of question marks, so please consider the above as the basis for discussion and not as the claims that I could verify as truth.
Željko Heimer, 5 June 2005

Article 92. Status of ships.

1. Ships shall sail under the flag of one State only and, save in exceptional cases expressly provided for in international treaties or in this Convention, shall be subject to its exclusive jurisdiction on the high seas. A ship may not change its flag during a voyage or while in a port of call, save in the case of a real transfer of ownership or change of registry.

2. A ship which sails under the flags of two or more States, using them according to convenience, may not claim any of the nationalities in question with respect to any other State, and may be assimilated to a ship without nationality.

Article 93.

Ships flying the flag of the United Nations, its specialized agencies and the International Atomic Energy Agency. The preceding articles do not prejudice the question of ships employed on the official service of the United Nations, its specialized agencies or the International Atomic Energy Agency, flying the flag of the organization.

David Prothero, 6 June 2005