In the 1931 case of Santovincenzo v. Egan, the U.S. Supreme Court ruled in favor of Consul Santovincenzo, representing the Kingdom of Italy. The dispute arose after an Italian citizen living in New York died intestate (without a will), leaving behind personal property valued at approximately $40,000. Under New York law, if no relatives came forward to claim such property within five years it would escheat (revert) to the state; however, under international treaty obligations and customary international law recognized by Congress and previous court decisions, consuls could protect their nationals' estates from escheatment by stepping into their shoes as "next friend" or representative for purposes of estate administration. The Public Administrator argued that this right was not absolute but subject to local laws governing estate distribution and succession - including escheat statutes like New York's - which applied equally regardless of nationality or domicile status. The Supreme Court disagreed with this interpretation: while states had broad powers over inheritance matters within their borders they couldn't infringe on federal prerogatives regarding foreign relations without express Congressional authorization – which didn’t exist here – so applying NY’s statute against Italian consul violated Supremacy Clause.

In the dissenting opinion for Santovincenzo v. Egan, Justice Stone argued that the majority's decision to allow a state law to interfere with international relations was incorrect. He contended that it is not within a state's power to determine how foreign governments should dispose of their property or conduct their affairs in the United States, as this falls under federal jurisdiction. Furthermore, he believed that allowing states such control could potentially lead to conflicts between nations and disrupt diplomatic relationships. Therefore, he disagreed with the court’s ruling which upheld New York State laws requiring foreign consuls to obtain permission from local courts before exporting deceased nationals' estates back home.