The case of the day is In re Application of Ruiz (S.D.N.Y. 2018). In 2017, European and Spanish banking regulators sold Banco Popular Español, a bank they thought failing, to Banco Santander for € 1. Investors in Banco Popular then sued in the EU’s Court of Justice, and some of them also brought investor-state arbitrations against Spain under the Mexico/Spain BIT. Finally, some of the investors sought to join Spanish criminal proceedings against Banco Popular and its former managers. The investors applied to the court under § 1782 for leave to take discovery of Santander (including the Spanish bank itself, which had a US branch, and some US subsidiaries) for use in the foreign proceedings. Although the judge framed the issue as whether the…