“After Argentina defaulted on between $80 and $100 billion of sovereign debt in 2001, numerous bondholders, including Appellee here and those in the related Seijas cases, filed suit. In Appellee’s suit, the District Court entered an order on May 29, 2009, that certified a class under a continuous holder requirement, i.e., the class contained only those individuals who, like Appellee, possessed beneficial interests in a particular bond series issued by the Republic of Argentina from the date of the complaint—December 19, 2006—through the date of final judgment in the District Court. After this Court held that the District Court’s method of calculating damages was inflated and remanded with instructions to conduct an evidentiary hearing, see Seijas I, 606 F.3d at 58–59; Seijas II, 493 Fed.Appx. at 160, the Appellee in this case offered the District Court an alternative solution to its difficulties in assessing damages—simply modifying the class definition by removing the continuous holder requirement and expanding the class to all holders of beneficial interests in the relevant bond series without limitation as to time held….

“The touchstone of ascertainability is whether the class is ‘sufficiently definite so that it is administratively feasible for the court to determine whether a particular individual is a member’….

“This case presents just such a circumstance where an objective standard—owning a beneficial interest in a bond series—is insufficiently definite to allow ready identification of the class or the persons who will be bound by the judgment. The secondary market for Argentine bonds is active and has continued trading after the commencement of this and other lawsuits. The nature of the beneficial interest itself and the difficulty of establishing a particular interest’s provenance make the objective criterion used here, without more, inadequate….

“Although the class as originally defined by the District Court may have presented difficult questions of calculating damages, it did not suffer from a lack of ascertainability. The District Court erred in attempting to address those questions by introducing an ascertainability defect into the class definition.”

Brecher v. Republic of Argentina, No.14-4385, 2015 WL 5438797 (2d Cir. Sept. 16, 2015).