A federal judge in Tierra del Fuego has ordered Rockhopper Exploration and Navitas Petroleum to halt all physical work on the Sea Lion oil project near the Malvinas (Falkland Islands), the most concrete legal setback yet to a $2.1 billion development that has become a flashpoint in Argentina's escalating dispute with Britain.
The Court Order
Federal Judge Mariel Borruto, sitting in Río Grande, issued the injunction on September 16, barring seabed drilling, the installation of subsea infrastructure and pipelines, deployment of floating production and storage units, and onshore or port support work until Argentina's national environmental authorities complete an impact assessment. The order gives the companies 10 days to report on the project's current status.
The suit was brought by CECIM La Plata, an association of Argentine veterans of the 1982 Malvinas war, together with the Civil Association of Environmental Lawyers and Professionals. It argues the companies never carried out the environmental impact assessment required under Argentina's General Environmental Law before starting work capable of causing ecological damage, citing risks from chemical pollution, underwater noise, ship traffic and potential spills. The claim separately invokes a 1976 United Nations resolution urging both countries to avoid unilateral changes while the sovereignty dispute remains unresolved.
Rockhopper and Navitas said in a joint statement that the ruling was "not expected to have a material effect on the project or its timetable," maintaining that their licenses, issued by the Falkland Islands government, are lawful and that Argentine courts have no jurisdiction over activity there. Both companies said drilling remains on track to begin in early 2027, targeting first oil in 2028. Judge Borruto herself acknowledged in the ruling that enforcement would depend on "international cooperation and the conduct of the companies involved" — language that echoes a similar 2015 Argentine seizure order against oil companies operating near the islands, which was never enforced because the firms held no meaningful assets inside Argentina.
Diplomatic Fallout
The ruling landed a day after Britain's Foreign, Commonwealth and Development Office published new guidance for businesses titled "Doing business with the Falkland Islands," reasserting UK sovereignty, stating that Argentina exercises no jurisdiction over the islands, and offering support to companies that receive legal correspondence from Argentine authorities. Argentina's foreign ministry issued its "strongest rejection" of the guidance on September 16, arguing the islands are Argentine territory "illegitimately occupied" by Britain and that the UK document itself violates the 1976 UN resolution. Foreign Minister Pablo Quirno summoned the British and Israeli ambassadors in Buenos Aires to deliver formal protest notes over Rockhopper and Navitas's decision to proceed with the project.
The Sea Lion field, discovered in 2010 and located roughly 220 kilometers north of the islands, received a final investment decision in December 2025 with a first-phase cost of about $1.8 billion, rising to $2.1 billion through completion. It is the centerpiece of the hydrocarbon activity that President Milei's government has targeted since early September, when it opened criminal complaints against Navitas and other firms and expanded a sanctions list to roughly 60 companies and individuals tied to oil exploration near the islands.
For now, the injunction changes little on the ground: Sea Lion's operators say their schedule is intact, and the same jurisdictional gap that left a 2015 order unenforced still applies. What it does is add a judicial track to a dispute that Argentina is already fighting through sanctions, criminal complaints and diplomatic protests — keeping Sea Lion, and the question of who has the legal authority to regulate it, at the center of the Malvinas standoff heading into Argentina's midterm elections.