Investment firms Petersen Energia and Eton Park petitioned the U.S. Supreme Court on Wednesday to reinstate a $16.1 billion judgment against Argentina in the long-running YPF litigation. The petition challenges a March ruling by the 2nd U.S. Circuit Court of Appeals, which held that the claims belonged in Argentine courts and overturned a judgment reached after more than a decade of litigation. The dispute stems from Argentina’s 2012 nationalization of a controlling 51% stake in YPF from Spain’s Repsol. The investors say Argentina violated YPF’s bylaws by failing to make a mandatory tender offer (an offer to buy shares from other holders) after regaining majority control. The petition raises questions under the Foreign Sovereign Immunities Act (U.S. law governing lawsuits against foreign states), including whether Argentina can invoke its own law to require litigation in its domestic courts and whether U.S. courts should defer to an interpretation first presented on appeal. Filed by former U.S. Solicitor General Paul Clement, the petition argues that the 2nd Circuit’s decision conflicts with Supreme Court precedent and creates a split among federal appellate courts. Argentina’s presidential office did not immediately respond, while YPF declined to comment.