The High Sea

  1. High Sea

Article 86 of the UNCLOS:

….all parts of the sea that are not included in the exclusive economic zone, in the territorial sea or in the internal waters of a State, or in the archipelagic waters of an archipelagic State. This article does not entail any abridgement of the freedoms enjoyed by all States in the exclusive economic zone in accordance with article 58.

The rule on high sea is founded upon the rule that the high seas were not open to acquisition by occupation on the part of states individually or collectively: it was res communis.

According to article 87 of the UNCLOS, the principles of the high seas are:

  1. The high seas are open to all States, whether coastal or land-locked.

Freedom of the high seas is exercised under the conditions laid down by this Convention and by other rules of international law. It comprises, inter alia, both for coastal and land-locked States:

 (a) freedom of navigation;

(b) freedom of overflight;

(c) freedom to lay submarine cables and pipelines, subject to Part VI;

(d) freedom to construct artificial islands and other installations permitted under international law, subject to Part VI;

(e) freedom of fishing, subject to the conditions laid down in section 2;

(f) freedom of scientific research, subject to Parts VI and XIII.


  1. These freedoms shall be exercised by all States with due regard for the interests of other States in their exercise of the freedom of the high seas, and also with due regard for the rights under this Convention with respect to activities in the Area.

In regard to freedom of fishing see, Anglo-Norwegian Fisheries and the Behring Sea Fisheries arbitration awards of 1893 and 1902. In all three cases the ICJ and the arbitral tribunals rejected the claims to enforce conservation measures against foreign vessels on the high seas.

UNCLOS however, places additional limitations upon the high-seas freedoms. The freedom to lay submarine cables and pipelines and construct artificial islans and other installations are subject to part VI. Freedom of scientific research is subject to parts VI and XIII. Finally freedom of fishing is subject to part VII, section 2. In particular articles 117 and 118 condition the freedom to fish by requiring states parties to cooperate with other states in taking such measures for their respective nationals as may be necessary for the conservation and management of living resources on the high seas, to the extent of establishing subregional or regional fisheries management organizations to this end.


Exercise of jurisdiction in the high sea

General rule: a state cannot interfere with vessels sailing under the flag of another state without the consent of the latter.

States have duty to fix conditions for the grant of nationality, for the registration of ships in its territory, and for the right to fly its flag. Ships have the nationality of the state whose flag they are entitled to fly.

Article 88: High seas are reserved for peaceful purposes.

Article 89: No state may claim sovereignty over high seas.

Article 90: Freedom of navigation of all states flying their flag.

Article 92: Ships fall under the jurisdiction of the flag state.

See article 94 for the duties of the flag state.


Exception to the general rule:

  1. Piracy

Article 101 UNCLOS:

(a) any illegal acts of violence or detention, or any act of depredation, committed for private ends by the crew or the passengers of a private ship or a private aircraft, and directed:

(i) on the high seas, against another ship or aircraft, or against persons or property on board such ship or aircraft;

(ii) against a ship, aircraft, persons or property in a place outside the jurisdiction of any State;

(b) any act of voluntary participation in the operation of a ship or of an aircraft with knowledge of facts making it a pirate ship or aircraft;

(c) any act of inciting or of intentionally facilitating an act described in subparagraph (a) or (b).


Article 105:

On the high seas, or in any other place outside the jurisdiction of any State, every State may seize a pirate ship or aircraft, or a ship or aircraft taken by piracy and under the control of pirates, and arrest the persons and seize the property on board. The courts of the State which carried out the seizure may decide upon the penalties to be imposed, and may also determine the action to be taken with regard to the ships, aircraft or property, subject to the rights of third parties acting in good faith.


2. Right to approach in time of peace

By warships to verify the identity and nationality of ships. This right is recognised by customary law but not expressly provided in the UNCLOS.


  1. Visit, Search and Seizure in time of peace

See article 110:

Right to Visit: (a) the ship is engaged in piracy;

(b) the ship is engaged in the slave trade;

(c) the ship is engaged in unauthorized broadcasting and the flag State of the warship has jurisdiction under article 109;

(d) the ship is without nationality; or

(e) though flying a foreign flag or refusing to show its flag, the ship is, in reality, of the same nationality as the warship.


3. Right to self-defence (no express provision in the UNCLOS)

4. Blockade and Contraband

Blockade of the enemy’s ports and coast may be justified.

Enforcement of blockade by confiscation of merchant ships that attempt to break the blockade.

The right of visit, search and capture may be exercised against neutral ships or aircraft carrying contraband or engaged in acts of non-neutral service.

5. Right of hot pursuit

A state may validly continue the pursuit commenced in the territorial water or contiguous zone of the vessels that violate the coastal state’s law.

See  article 111.

Hall provided the rationale of hot pursuit:

“the reason for the permission seems to be that pursuit under these circumstances is a continuation of an act of jurisdiction which has been begun, or which but for the accident of immediate escape would have been begun, within the territory itself, and that it is necessary to permit it in order to enable the territorial jurisdiction to be efficiently exercised.”

The hot pursuit is exhausted when the vessel enters into territorial water of another coastal state.

6. Restrictions by treaty

Example: The Convention for the Protection of Submarine Cables of 1884.