The dredger Zheng He, owned and operated by a Luxembourg company and flying the flag of Luxembourg, arrived in an anchorage area in the Mexican territorial sea. The shipowner agent transmitted to the port authorities in Tampico, Mexico, a request for authorisation to dock the vessel in the port 'for approximately 3 to 4 weeks' in order 'to await instructions and, in the meantime, for provisioning, crew change, garbage and sludge removal'. The authorisation was given, and the vessel berthed.

On 1 November 2023, the Mexican authorities detained the vessel following an onboard inspection. Mexico contended that, during the onboard inspection, neither the shipowner nor its agent 'presented customs documentation demonstrating the legal importation, stay, and possession of the Zheng He in national territory, in contravention of the Mexican Customs Law'.

The shipowner instituted legal proceedings before the Tampico District Court, challenging the actions of Mexican authorities.

Mexican authorities confiscated the dredger and imposed a 'tax credit' of MXN 1,616,462,343.62 on the shipowner.

The Tampico District Court issued a judgment. Luxembourg submitted that the Court ruled that the customs proceedings against the dredger were null and void. Mexico contended that the Court's decision was not final, and the legal status of the vessel was the subject of litigation before a higher court.

Luxembourg submitted a number of notes verbales to Mexico, where it requested, among other things, a solution of the situation within the framework of international law. The representatives of the parties conducted a meeting during which references were made to the right of innocent passage, and Luxembourg expressed its intention to settle the dispute by recourse to the International Tribunal of the Law of the Sea (the Tribunal). The single note verbale submitted by Mexico to Luxembourg with regard to the dredger referred to that very meeting and stated, in particular, that there were various administrative and judicial remedies available 'under Mexican law'. Luxembourg's two subsequent notes verbales remained unanswered by Mexico.

Luxembourg contended, among other things, that Mexico had violated its obligation under art 131 of the United Nations Convention on the Law of the Sea 1982 (UNCLOS) to grant ships flying the flag of landlocked States treatment equal to that accorded to other foreign ships. Luxembourg requested the Tribunal to prescribe provisional measures in order to, among other things, preserve the fundamental rights and freedom of the crew, and preserve the rights of Luxembourg as the flag State.

According to Luxembourg, the request for the prescription of provisional measures was motivated by 'established urgency, which grows with each day of the detention, the race towards the domestic courts, the inevitable deterioration of the vessel, and the proven and imminent risk of losing the classification and certification, with all that this would entail for the real rights and the nationality of our vessel'. Mexico contended that there was no risk of an imminent and irreparable prejudice to the rights claimed by Luxembourg.

Held: By 22 votes to 1, the Tribunal finds that the circumstances do not require the prescription of provisional measures under art 290.1 of UNCLOS.

Before prescribing provisional measures under art 290.1 of the UNCLOS, the Tribunal must satisfy that prima facie it has jurisdiction over the dispute regarding the dredger. According to art 288.1, the Tribunal must determine whether, on the date of the institution of the proceedings on the merits, a dispute appeared to have existed between the parties and, if so, whether such dispute concerned the interpretation or application of the UNCLOS.

Although Mexico did not directly respond to Luxembourg's assertion of rights under the UNCLOS regarding the dredger's detention before proceedings were instituted, its conduct indicates its view on this question. Therefore, prima facie, a dispute concerning the interpretation or application of the UNCLOS existed between the parties. At this stage of the proceedings, the Tribunal needs to satisfy itself that at least one of the provisions of the UNCLOS appear prima facie to afford a basis upon which the Tribunal's jurisdiction might be found. Article 131 of the UNCLOS affords such a basis.

When a dispute arises, art 283 requires the parties to 'proceed expeditiously to an exchange of views regarding its settlement by negotiation or other peaceful means'. This obligation refers to the means of settling the dispute and cannot be understood as an obligation to negotiate the substance of the dispute. This obligation applies equally to both parties to the dispute. A State Party is not obliged to continue with an exchange of views when it concludes that the possibilities of reaching an agreement have been exhausted. The referral by Mexico solely to the legal means available to Luxembourg under the national law of Mexico could reasonably lead Luxembourg to conclude that all possibilities of reaching an agreement were exhausted.

In the circumstances of this case, the requirement of exhaustion of local remedies under art 295 should be examined at a future stage of the proceedings. Therefore, the Tribunal prima facie has jurisdiction over the dispute.

The object of the Tribunal's power to prescribe provisional measures under art 290.1 is to preserve the rights of the parties to the dispute, pending the final decision. The Tribunal was not called upon to determine definitively whether the rights claimed by the applicant existed, but needed only to decide whether such rights were plausible. The rights claimed by Luxembourg in the present case on the basis of art 131 were plausible.

Under art 290.1, the Tribunal may prescribe provisional measures if the urgency of the situation so requires. Urgency implies that there is a real and imminent risk that irreparable prejudice may be caused to the rights of the parties to the dispute, pending the final decision. Based on the factual information and legal arguments presented by the parties, the Tribunal considered that there was no urgency, in the sense that there was no real and imminent risk of irreparable prejudice to Luxembourg's rights.