Professor Antonios Tzanakopoulos contributes to landmark US Supreme Court case addressing foreign sovereign immunity

A group of international law scholars and experts on the law of immunity, including Professor Antonios Tzanakopoulos of the Faculty of Law and Professor Philippa Webb of Oxford's Blavatnik School of Government, have filed an amicus curiae brief with the United States Supreme Court in the case of Exxon Mobil Corp. v Corporación Cimex, S.A. (Cuba) et al.

Submitted in support of the Respondents, the brief argues that the opinion of the Court of Appeals for the D.C. Circuit that the Helms-Burton Act 1996 and its Title III did not implicitly override the Foreign Sovereign Immunity Act 1976 is in line with customary international law and should be affirmed. The case is set for argument on 23 February 2026.

Background

The case concerns the relationship between two US statutes: the Foreign Sovereign Immunities Act (FSIA), which generally protects foreign states and their entities from being sued in US courts, and Title III of the Helms-Burton Act, which allows US nationals to bring civil claims relating to property seized by the Cuban government after the 1959 revolution. In this example, Exxon is suing Cimex for the alleged trafficking of property owned by an Exxon subsidiary company in the early 1960s. This has been possible since 2019, when the Trump administration lifted a suspension on Title III. The Supreme Court is being asked to decide whether Congress intended the Helms-Burton Act to remove the protections normally afforded to foreign states under the FSIA.

An amicus curiae brief – literally a submission by a 'friend of the court' – is filed by individuals or organisations who are not parties to the case but have relevant expertise. Such briefs are intended to assist the court by providing specialist legal analysis or broader context – particularly where a case raises complex or far-reaching issues of law.