This Supplemental Brief was filed by the Petitioner, the Kingdom of Spain, before the Supreme Court of the United States in support of its Petition for a Writ of Certiorari. The petition seeks review of a judgment from the U.S. Court of Appeals for the District of Columbia Circuit concerning the enforcement of an ICSID arbitral award. The brief's primary purpose is to rebut arguments made by the Respondents, Blasket Renewable Investments et al., particularly those relying on a recent Australian trial court decision, and to reassert the importance of the legal questions presented for the Court's review.

Spain contends that the Respondents' reliance on a recent Australian trial court decision, which permitted enforcement of a similar award against Spain, is misplaced and irrelevant. Petitioner argues that the Australian court's ruling interprets Australian domestic law (the Foreign States Immunities Act of 1985), which contains materially different language regarding waiver of immunity compared to the U.S. Foreign Sovereign Immunities Act (FSIA). Furthermore, Spain highlights that the Australian decision is a first-instance judgment subject to appeal. In contrast, Spain cites a recent Israeli court decision that declined to enforce an ICSID award against it on the grounds of forum non conveniens, directly contradicting the Respondents' assertion that the doctrine is unavailable in such proceedings.

The brief reiterates that the case presents two critical and recurring questions of U.S. law that have created a circuit split. The first concerns the proper interpretation of the FSIA's arbitration exception, 28 U.S.C. § 1605(a)(6). Spain argues the D.C. Circuit erred by failing to determine whether Spain had agreed to arbitrate the specific "differences between the parties," thereby nullifying a key jurisdictional prerequisite. The second question addresses the availability of the forum non conveniens doctrine in actions to enforce ICSID awards. Spain maintains that the D.C. Circuit's holding that the doctrine is unavailable conflicts with established legal principles and creates an improper incentive for forum shopping. The brief emphasizes the exceptional importance of these issues for foreign sovereigns, as evidenced by amicus briefs filed in support of the petition.

Ultimately, Spain asserts that the Respondents' supplemental arguments are improper and unsound, recycling previously refuted points. The Petitioner urges the Supreme Court to grant the petition for a writ of certiorari to resolve the significant legal questions presented and to decline the Respondents' invitation to address other issues not decided by the lower courts.