On June 16, 2014, the United States Supreme Court held that the Foreign Sovereign Immunities Act (FSIA) does not prevent a judgment creditor from conducting postjudgment discovery into a foreign sovereign's assets outside the United States.

The Republic of Argentina, defaulted on debt securities that NML Capital, Ltd. purchased. NML sued Argentina in federal district court in the U.S. to collect the debt, and prevailed. (Argentina had waived its sovereign immunity from suit in the United States).  NML then served two third-party subpoenas on banks to discover information about Argentina's property and financial transactions. One of the banks, joined by Argentina, moved to quash the subpoena, and NML moved to compel. The district court denied the motion to quash and granted NML's motion to compel, but limited the scope of request to information "reasonably calculated to lead to attachable property." As a practical matter, this limited the scope of the subpoena to property outside the United States, as Argentina's property in the United States is immune from execution. Argentina appealed, arguing that FSIA gave it immunity from postjudgment discovery in aid of execution on its assets. The Second Circuit Court of Appeals affirmed the district court.

The Supreme Court also affirmed, holding that the case presented the "narrow question" whether the FSIA precludes the use of third-party subpoenas to discover the assets of a foreign sovereign that has waived its immunity from being sued in the United States. The Court held that the answer is no. First, the Court noted that rules in Fed. R. Civ. P. 69 governing postjudgment execution proceedings are very permissive, and generally allow discovery from any person to the extent provided by the other rules of civil procedure, including the normal discovery rules. Next, the Court noted that the FSIA provides a "comprehensive" set of legal standards that govern the immunity of foreign sovereigns such as Argentina. And nowhere in that comprehensive scheme did Congress forbid or limit discovery in aid of execution of a foreign sovereign's assets. While the FSIA may bar actual attachment of or execution on certain assets of a foreign sovereign located in the United States, it does not bar postjudgment discovery to ascertain the extent and location of a foreign sovereign's assets that may be subject to attachment or execution.

Justice Scalia delivered the opinion of the Court, which was joined by Chief Justice Roberts and Justices Kennedy, Thomas, Breyer, Alito and Kagan. Justice Ginsburg filed a dissenting opinion. Justice Sotomayor took no part in the decision of the case.