Flag State and Flags of Convenience
The legal basis of the flag, what a flag state must do, the genuine link debate, the share of open registers and the false flag problem.
A flag state is the country whose register a ship is entered on and whose flag she is entitled to fly. The ship takes her nationality from that state, falls under its jurisdiction on the high seas and carries certificates issued in its name. The owner can be of any nationality. On UNCTAD's figures for 1 January 2025, Liberia held 17.4% of world carrying capacity, Panama 15.2% and the Marshall Islands 12.5%, which together comes to 45.1%.[1]
Legal Framework
The governing text is Part VII of the 1982 UN Convention on the Law of the Sea (UNCLOS). Article 90 gives every state, coastal or land-locked, the right to sail ships under its flag on the high seas.[2] The key provisions are these.
| Article | What it says |
|---|---|
| 91 | Each state sets its own conditions for nationality and registration. A ship has the nationality of the state whose flag she is entitled to fly, and there must be a genuine link between the two. |
| 92 | A ship sails under one flag only. She cannot change it during a voyage or in a port of call unless ownership or registry has really changed. A ship using two flags as it suits her may be treated as stateless. |
| 94 | The flag state must effectively exercise jurisdiction and control in administrative, technical and social matters. It keeps a register and sees to construction, equipment, crewing and navigational safety. |
| 94(6) | A state with clear grounds to think proper control is lacking may report the facts to the flag state, which must investigate. |
| 97 | After a collision on the high seas, penal or disciplinary proceedings against the master or crew can be brought only by the flag state or the state of the person's nationality. |
| 110 | A warship may board a foreign ship only on specified suspicions. One of them is that the ship has no nationality. |
Source: UNCLOS, Part VII.[2]
Pollution enforcement also falls to the flag state. Under article 217 it must investigate alleged violations wherever they occur, keep non-compliant ships from sailing and apply penalties severe enough to discourage repetition.[3]
The Genuine Link
UNCLOS does not define the genuine link. In the M/V Saiga (No. 2) judgment of 1999, the International Tribunal for the Law of the Sea rejected Guinea's objection to the ship's nationality on this ground and said the purpose of the provisions is to secure more effective implementation of flag state duties.[4] The 1986 UN Convention on Conditions for Registration of Ships tried to tighten the concept but has never entered into force. It needs 40 states holding more than 25% of world tonnage.[5]
Legal Consequences of the Flag
Jurisdiction is the main consequence. On the high seas a ship answers in principle only to her flag state, and other states can intervene only in the cases the Convention lists, among them suspected piracy, slave trading and unauthorised broadcasting. After a collision, no authority but the flag state may arrest or detain the ship, even for investigation.[2]
The flag state must also put a duty of assistance on its masters. Article 98 requires a master to help anyone in danger at sea, so far as that creates no serious danger to his own ship, and after a collision to give the other vessel his ship's name, port of registry and next port of call.[2] Once in port the position shifts. The ship stays under her flag's law but also comes under the rules and inspection of the port state, so a single voyage routinely brings several legal systems into play. Which one governs a given dispute is a question for maritime law.
National and Open Registers
A national register ties the ship to citizens or companies of that country. An open register accepts foreign-owned tonnage with minimal nationality requirements.[1] "Flag of convenience" is mainly the label used by the International Transport Workers' Federation (ITF), which has campaigned against such registers since 1948 and keeps its own list. Adding Dominica, Gambia and Niue in November 2025 took that list to 48 flags.[5][6]
The story usually begins with Panama. In August 1919 the Belen Quezada became the first foreign ship re-registered there, and went on to run alcohol from Canada into Prohibition-era America. The Liberian register was founded in 1948, and Stavros Niarchos entered its first ship, World Peace, on 11 March 1949. After Edward Stettinius died that year, ownership of the register passed to the International Bank of Washington.[5]
| Rank | Flag | Vessels | Deadweight (thousand tons) | Share of world capacity |
|---|---|---|---|---|
| 1 | Liberia | 5,562 | 424,063 | 17.4% |
| 2 | Panama | 8,572 | 371,301 | 15.2% |
| 3 | Marshall Islands | 4,254 | 305,471 | 12.5% |
| 4 | Hong Kong, China | 2,513 | 203,048 | 8.3% |
| 5 | Singapore | 3,098 | 152,344 | 6.2% |
| 6 | China | 10,288 | 137,064 | 5.6% |
| 7 | Malta | 1,949 | 113,194 | 4.6% |
| 8 | The Bahamas | 1,251 | 70,463 | 2.9% |
Source: UNCTAD, Review of Maritime Transport 2025, Table II.2, 1 January 2025.[1]
Numbers of ships and capacity tell different stories. China has 10,288 vessels but ranks sixth by capacity because its ships average much smaller, while Liberia has fewer ships than Panama and more deadweight. The top ten flags hold 76.7% of world capacity.[1]
Owners weigh tax treatment, crewing rules, registry fees and administrative ease. An open register does not by itself mean poor quality, and the most concrete measure of a flag's record is the annual performance lists of port state control regimes. The Paris MoU list built on 2023 to 2025 data, in force from 1 July 2026, puts 40 flags on the white list.[7] Türkiye's two registers, the national one and the Turkish International Ship Registry, are compared under ship registration.
What a Flag State Does
It enters ships on the register, issues statutory certificates, arranges surveys, recognises seafarers' certificates and investigates casualties. Much of the technical work is delegated to authorised classification societies, while responsibility stays with the state that delegated it. Where oversight falls short, port state control is the backstop.
IMO keeps this performance on its agenda through the Sub-Committee on Implementation of IMO Instruments (III).[8]
Changing Flag
Reflagging means deletion from the old register and entry on the new one. The ship's name, MMSI and call sign may change, and her IMO number does not. Her registry history is kept on board in the Continuous Synopsis Record. Article 92 rules out switching flags at will during a voyage. Temporary dual registration during a bareboat charter is a separate arrangement with its own rules.
False Flags
A false flag is one a ship has no right to fly. The IMO Legal Committee's 113th session, on 13 to 17 April 2026, recorded 529 ships falsely flying another country's flag over the previous year, and nearly 40 member states had seen their flags misused by criminal groups. The same session approved what IMO calls the first international guidelines to deter fraud and misuse of flags, aimed at transparency and due diligence in registration.[9]
The issue overlaps with sanctions. UNCTAD reports assessments linking rapid growth in some minor flags to the "shadow fleet", described as mainly older tankers with poor maintenance, unclear ownership and inadequate insurance. Clarksons Research put about 3% of world gross tonnage under sanctions by May 2025.[1] Ports, insurers and fuel suppliers therefore increasingly compare the declared flag with the registry record. The ship's name and IMO number given at the enquiry stage are the starting point for that check.
Frequently asked questions
What is a flag state?
The state where a ship is registered and whose flag she may fly. It determines her nationality and legal link on the high seas.
What does flag of convenience mean?
A label for a ship registered on an open register outside her owner's country. The ITF keeps its own list.
Can a land-locked country have a ship register?
Yes. UNCLOS article 90 gives every state, coastal or land-locked, the right to sail ships under its flag on the high seas.
Which is the largest flag state?
Liberia by carrying capacity. By number of vessels, Indonesia and China lead on the UNCTAD table, so the answer depends on the measure.
Sources
- UNCTAD. Review of Maritime Transport 2025, Chapter II and Table II.2.
- United Nations. Convention on the Law of the Sea, Part VII, Articles 90, 91, 92, 94, 97 and 110, 1982.
- United Nations. Convention on the Law of the Sea, Part XII, Article 217, 1982.
- International Tribunal for the Law of the Sea. The M/V "Saiga" (No. 2) Case, Saint Vincent and the Grenadines v. Guinea, 1 July 1999.
- Wikipedia. Flag of Convenience. Used as a secondary source.
- Seafarers International Union. ITF Adds 3 Flags to FOC List, January 2026; World Ports Organization. ITF Adds Three New Flags as FOC, 2025.
- Cyprus Mail. Cyprus Retains Position on Paris MoU White List, 3 July 2026.
- International Maritime Organization. Structure of IMO.
- International Maritime Organization. IMO Approves New Guidelines on Ship Registration, April 2026.
