This case arose from the arrest and detention of the Argentinian frigate, the ARA Libertad, in the Ghanaian port of Tema.

Argentina requested an arbitral tribunal to be constituted under Annex VII of the United Nations Convention on the Law of the Sea 1982 (UNCLOS) to declare that the Republic of Ghana, by detaining the warship ARA Fragata Libertad, keeping it detained, not allowing it to refuel and adopting several judicial measures against it:

(1) violates the international obligation of respecting the immunities from jurisdiction and execution enjoyed by such vessel pursuant to art 32 of UNCLOS and art 3 of the Convention for the Unification of Certain Rules concerning the Immunity of State-owned Vessels 1926 as well as pursuant to well-established general or customary international law rules in this regard; and

(2) prevents the exercise of the right to sail out of the waters subject to the jurisdiction of the coastal State and the right of freedom of navigation enjoyed by the vessel and its crew, pursuant to arts 18.1.b, 87.1.a and 90 of UNCLOS.

Held: The Tribunal: (1) unanimously prescribes, pending a decision by the Annex VII arbitral tribunal, the following provisional measures under art 290.5 of UNCLOS: Ghana shall forthwith and unconditionally release the frigate ARA Libertad, shall ensure that the frigate ARA Libertad, its commander and crew are able to leave the port of Tema and the maritime areas under the jurisdiction of Ghana, and shall ensure that the frigate ARA Libertad is resupplied to that end;

(2) unanimously decides that Argentina and Ghana shall each submit an initial report not later than 22 December 2012 to the Tribunal, and authorises the President to request such information as he may consider appropriate after that date; and

(3) unanimously decides that each party shall bear its own costs.

Article 18.1.b of UNCLOS on the meaning of passage in the territorial sea and arts 87 and 90 concerning the right and freedom of navigation on the high seas do not relate to the immunity of warships in internal waters and therefore do not seem to provide a basis for prima facie jurisdiction of the Annex VII arbitral tribunal.

Article 32 of UNCLOS states that 'nothing in this Convention affects the immunities of warships' without specifying the geographical scope of its application. Although art 32 is included in Part II of the Convention entitled 'Territorial Sea and Contiguous Zone', and most of the provisions in this Part relate to the territorial sea, some of the provisions in this Part may be applicable to all maritime areas, as in the case of the definition of warships provided for in art 29 of the Convention. In the light of the positions of the parties, a difference of opinions exists between them as to the applicability of art 32 and thus the Tribunal is of the view that a dispute appears to exist between the parties concerning the interpretation or application of the Convention. Article 32 thus affords a basis on which prima facie jurisdiction of the Annex VII arbitral tribunal may be founded.

In the circumstances of the present case, the Tribunal is of the view that the requirements of art 283 of UNCLOS about exchanges of views are satisfied.

In accordance with art 29 of UNCLOS, 'warship' means a ship belonging to the armed forces of a State bearing the external marks distinguishing such ships of its nationality, under the command of an officer duly commissioned by the government of the State and whose name appears in the appropriate service list or its equivalent, and manned by a crew which is under regular armed forces discipline. A warship is thus an expression of the sovereignty of the State whose flag it flies. In accordance with general international law, a warship enjoys immunity, including in internal waters, and this is not disputed by Ghana. In accordance with art 279 of UNCLOS, 'States Parties shall settle any dispute between them concerning the interpretation or application of this Convention by peaceful means in accordance with Article 2, paragraph 3, of the Charter of the United Nations'. Any act which prevents by force a warship from discharging its mission and duties is a source of conflict that may endanger friendly relations among States. The actions taken by the Ghanaian authorities that prevent the ARA Libertad, a warship belonging to the Argentine Navy, from discharging its mission and duties affect the immunity enjoyed by this warship under general international law. Attempts by the Ghanaian authorities on 7 November 2012 to board the warship ARA Libertad and to move it by force to another berth without authorisation by its commander and the possibility that such actions may be repeated, demonstrate the gravity of the situation and underline the urgent need for measures pending the constitution of the Annex VII arbitral tribunal. Pursuant to art 290.5 of UNCLOS, the urgency of the situation requires the prescription by the Tribunal of provisional measures that will ensure full compliance with the applicable rules of international law, thus preserving the respective rights of the parties.