This article investigates whether and to what extent a party must produce an “agreement in writing” when seeking to enforce an international arbitration agreement or award in a U.S. federal court. This issue has recently given rise to both a circuit split and a petition for certiorari to the U.S. Supreme Court, and involves matters of formal validity as well as federal subject matter jurisdiction. The problem arises out of subtle differences in the way an “agreement in writing” is defined in the Federal Arbitration Act (FAA) and the 1958 United Nations Convention on the Recognition and Enforcement of Foreign Arbitral Awards (New York Convention). This is not just a U.S. problem, however. Questions relating to form requirements under the New...