As we previously covered, the Tenth Circuit in Cline v. Sunoco, Inc. (R&M), 159 F.4th 11711 (10th Cir. 2025) adopted the majority view that “administrative feasibility” for identifying class members is not an independent requirement for certifying a class under Rule 23. Instead, the Tenth Circuit held that ascertainability only requires the party moving for class certification to present a “sufficiently definite” class definition that will allow the court to identify class members at some stage of the proceeding. The Tenth Circuit therefore rejected the minority view from the Third Circuit that ascertainability also requires plaintiffs to show that there is a reliable and administratively feasible mechanism to determine class membership.
Earlier this month, in Rider, Trustee of Cherry Rider Fam. Tr. v. OXY USA, Inc., — F.4th —-, 2026 WL 1218374 (10th Cir. May 5, 2026), the Tenth Circuit emphasized this holding from Cline by reversing a district court’s (pre-Cline) denial of class certification on the ground that the proposed class was not ascertainable because it was not administratively feasible to identify class members. The plaintiffs in Rider allege that defendants breached a 2008 settlement agreement regarding royalty payments for their interests in a gas field. The district court denied plaintiffs’ motion for class certification, primarily on ascertainability grounds, after finding that it would not be administratively feasible to determine which individuals owned mineral interests in land covered by the settlement agreement. Without the benefit of Cline, the district court had applied the minority view regarding ascertainability and found that the class was not ascertainable because the court would have to conduct individualized inquiries into payment, lease, acquisition, and other records to assess the land ownership chain for each potential class member.
The Tenth Circuit reversed the district court and remanded the case with instructions to certify the class. The court explained that the class was ascertainable under Cline because “the proposed class definition is clearly defined and not vague” and “the class is defined by objective criteria.” The court also held that the proposed class was not overbroad, even if the class definition might include some individuals who did not have any rights to royalty payments under the settlement agreement, because “at the class certification stage, the class need only be ascertainable (not already ascertained) with reasonable accuracy.” Finally, the court held that the proposed class satisfied the other Rule 23 requirements for class certification, finding that the key common question (whether defendants breached the settlement agreement) predominated over any individual questions regarding whether class members still owned an interest in royalty payments—an issue that the court held could be resolved at the damages stage of the case.
Rulings such as Cline and Rider do not, however, mean that issues about administrative feasibility are irrelevant to class certification. As the Rider court noted, “administrative feasibility may bear on whether class resolution is superior to individual resolution”—one of the factors plaintiffs must satisfy to certify a class under Rule 23(b)(3). So although many courts have rejected arguments that putative classes are not ascertainable if they are not administratively feasible, courts still must consider whether administrative difficulties show that a class action is not superior to other methods to fairly and efficiently adjudicate a case.