Ocean Policy · Offshore Oil

Argentina Takes the UK to the Law of the Sea Tribunal Over the Sea Lion Oil Project North of the Falklands

Hearings open in Hamburg on 10 November. Before they do, an Argentine court has ordered the project suspended, the government has filed a criminal complaint against its operator, and environmental lawyers are making the case that the South Atlantic’s whales, sea lions and penguins are at risk.

By SEVENSEAS Media | Ocean Policy

On 10 and 11 November, Argentina and the United Kingdom will put their arguments to the International Tribunal for the Law of the Sea in Hamburg over an oil field that neither of them is developing. Sea Lion sits roughly 200 kilometres north of the Falkland Islands (Malvinas), which Britain administers and Argentina claims. It is operated by Israel’s Navitas Petroleum, which holds 65 percent, with Britain’s Rockhopper Exploration holding the rest. According to Navitas, the partners took their final investment decision in December 2025 and plan first production in March 2028.

Argentina lodged its request for provisional measures on 13 October. As described in the tribunal’s announcement, reported by the Spanish agency EFE, Buenos Aires is asking the court to order the UK to stop using information gathered during exploration, to issue no further licences on the disputed continental shelf, and to stop preventing Argentina from meeting its own obligation under the Law of the Sea convention to protect and preserve the marine environment in the disputed waters.

What is being built

Navitas submitted an environmental impact statement to the Falkland Islands Government under the islands’ Offshore Minerals Ordinance, covering drilling and offshore production for Phases 1 and 2 of the Sea Lion Field Northern Development Area. The islands’ government put it out for public consultation in 2024 and announced in December 2025 that it had approved the project. Plans filed in the Argentine lawsuit describe 23 wells, a mix of oil-producing, water-injection and gas-injection wells, along with offshore production and transport infrastructure. Rockhopper said in May 2026 that the first two phases would use the Aoka Mizu, a floating production, storage and offloading vessel with capacity for 55,000 barrels a day.

London treats the field as a matter for the islands. In the House of Commons in September, Foreign Office Minister Kirsty McNeill described hydrocarbon production as a commercial decision for the islands’ government and the companies involved, MercoPress reported.

The environmental case

The first case to reach a courtroom came from civil society. On 1 September the Argentine Association of Environmental Lawyers (AADEAA) and the Malvinas Islands La Plata Ex-Combatants Center (CECIM), a veterans’ organisation, filed suit in the federal court in Río Grande, Tierra del Fuego. Their complaint, reported in detail by Inside Climate News, argues that Sea Lion has no environmental impact assessment or authorisation under Argentine law. It says the project would bring seabed disturbance, heavy ship traffic, underwater noise and the risk of a major spill into waters used by southern right whales, South American sea lions, penguins, orcas and dolphins, putting their feeding, breeding and migration at risk.

The plaintiffs describe the Argentine Sea and the South Atlantic islands as a biological bridge between South American marine life and Antarctica. They also lean on the rights of nature, arguing that the affected ecosystems are entitled to keep their integrity, and on a 2025 advisory opinion from the Inter-American Court of Human Rights on states’ duties to protect and restore ecosystems. The complaint goes further than the environment, too. It frames the project as resource extraction from occupied territory and asks the court to block financial transactions linked to it.

We believe we have a very good chance of securing a landmark ruling.

Enrique Viale, president, Argentine Association of Environmental Lawyers, to Inside Climate News

On 16 September the Río Grande court ordered the project suspended. AFP described the ruling as largely symbolic, since the UK does not recognise Argentine jurisdiction over the islands.

The government follows

President Javier Milei’s government moved within days. On 8 September Foreign Minister Pablo Quirno filed a criminal complaint against three Navitas entities and two other firms, JHI Associates and Eco (Atlantic) Oil & Gas, under a 2011 law that bars taking part in, financing or servicing unauthorised hydrocarbon activity on the Argentine continental shelf. MercoPress noted that the allegations are unproven, and that Argentina had already declared activity in the area clandestine in 2012 and filed a similar complaint in 2015 without halting the project. It also reported that CASEPE, the Argentine chamber of oil services companies, said its members would not work on Sea Lion.

Navitas has said it does not expect the Argentine measures to have a material effect on the project or its timetable. Both companies maintain that their licences were validly issued by the self-governing Falklands government, which Argentina does not recognise.

Whether the tribunal can rule at all

Under Article 286 of the convention, the tribunal settles disputes over its interpretation or application. Territorial disputes have traditionally gone to the International Court of Justice. Donald Rothwell, professor of international law at the Australian National University, argued in the Lowy Institute’s The Interpreter that Argentina’s case “could fall at the first hurdle” for that reason. In his reading, the claims about the continental shelf and environmental damage cannot be separated from the sovereignty question: if the islands are British, Sea Lion is lawful development of their shelf, and if Argentina’s claim holds, it is not. He also points out that the tribunal has generally been reluctant to read its own jurisdiction narrowly, citing the boundary case between Mauritius and the Maldives around the Chagos Archipelago, which it decided while sovereignty there was still contested.

That leaves the environmental questions about Sea Lion in an awkward place. They are now being argued almost entirely in proceedings framed around sovereignty, which is the issue most likely to decide them. In Río Grande, meanwhile, the plaintiffs have said their aim is the project’s money: Viale told Inside Climate News that without funding there can be no extraction.

The plaintiffs’ summary of the Río Grande lawsuit is published by the Argentine Association of Environmental Lawyers. Navitas’s environmental impact statement for Sea Lion is available from the Falkland Islands Government.